Quectel Wireless Solutions 201606EC21A Users Manual

EC21 Hardware Design

LTE Module Series

Rev. EC21_Hardware_Design_V1.5

Date: 2017-03-05

Status: Released

www.quectel.com

LTE Module Series

EC21 Hardware Design

Our aim is to provide customers with timely and comprehensive service. For any assistance, please contact our company headquarters:

Quectel Wireless Solutions Co., Ltd.

7th Floor, Hongye Building, No.1801 Hongmei Road, Xuhui District, Shanghai 200233, China Tel: [phone]

Email: [e-mail]

Or our local office. For more information, please visit:

http://quectel.com/support/sales.htm

For technical support, or to report documentation errors, please visit: http://quectel.com/support/technical.htm

Or Email to: [e-mail]

GENERAL NOTES

QUECTEL OFFERS THE INFORMATION AS A SERVICE TO ITS CUSTOMERS. THE INFORMATION PROVIDED IS BASED UPON CUSTOMERS’ REQUIREMENTS. QUECTEL MAKES EVERY EFFORT TO ENSURE THE QUALITY OF THE INFORMATION IT MAKES AVAILABLE. QUECTEL DOES NOT MAKE ANY WARRANTY AS TO THE INFORMATION CONTAINED HEREIN, AND DOES NOT ACCEPT ANY LIABILITY FOR ANY INJURY, LOSS OR DAMAGE OF ANY KIND INCURRED BY USE OF OR RELIANCE UPON THE INFORMATION. ALL INFORMATION SUPPLIED HEREIN IS SUBJECT TO CHANGE WITHOUT PRIOR NOTICE.

COPYRIGHT

THE INFORMATION CONTAINED HERE IS PROPRIETARY TECHNICAL INFORMATION OF QUECTEL WIRELESS SOLUTIONS CO., LTD. TRANSMITTING, REPRODUCTION, DISSEMINATION AND EDITING OF THIS DOCUMENT AS WELL AS UTILIZATION OF THE CONTENT ARE FORBIDDEN WITHOUT PERMISSION. OFFENDERS WILL BE HELD LIABLE FOR PAYMENT OF DAMAGES. ALL RIGHTS ARE RESERVED IN THE EVENT OF A PATENT GRANT OR REGISTRATION OF A UTILITY MODEL OR DESIGN.

Copyright © Quectel Wireless Solutions Co., Ltd. 2018. All rights reserved.

EC21_Hardware_Design

1 / 105

LTE Module Series

EC21 Hardware Design

About the Document

History

Revision	Date	Author	Description
1.0	2016-04-15	Yeoman CHEN	Initial
			1.	Updated frequency bands in Table 1.
			2.	Updated transmitting power, supported maximum
				baud rate of main UART, supported internet
				protocols, supported USB drivers of USB interface,
				and temperature range in Table 2.
			3.	Updated timing of turning on module in Figure 12.
			4.	Updated timing of turning off module in Figure 13.
		Yeoman CHEN/	5.	Updated timing of resetting module in Figure 16.
1.1	2016-09-22	Frank WANG/	6.	Updated main UART supports baud rate in Chapter
		Lyndon LIU		3.11.

7.Added notes for ADC interface in Chapter 3.13.

8.Updated GNSS Performance in Table 21.

9.Updated operating frequencies of module in Table 23.

10.Added current consumption in Chapter 6.4.

11.Updated RF output power in Chapter 6.5.

12.Added RF receiving sensitivity in Chapter 6.6.

					1.	Updated frequency bands in Table 1.
					2.	Updated function diagram in Figure 1.
					3.	Updated pin assignment (top view) in Figure 2.
					4.	Added BT interface in Chapter 3.18.2.
					5.	Updated reference circuit of wireless connectivity
	1.3		2017-01-24	Lyndon LIU/		interfaces with FC20 module in Figure 29.
				Rex WANG	6.	Updated GNSS performance in Table 24.
					7.	Updated module operating frequencies in Table 26.
					8.	Added EC21-AUV current consumption in Table 38.
					9.	Updated EC21-A conducted RF receiving sensitivity
						of in Table 42.
					10.	Added EC21-J conducted RF receiving sensitivity in
	EC21_Hardware_Design					2 / 105

				LTE Module Series
				EC21 Hardware Design
				Table 48.
1.4	2017-03-01	Geely YANG	Deleted the LTE band TDD B41 of EC21-CT
			1.	Updated functional diagram in Figure 1.
			2.	Updated frequency bands in Table 1.
			3.	Updated UMTS and GSM features in Table 2.
			4.	Updated description of pin 40/136/137/138.
			5.	Updated PWRKEY pulled down time to 500ms in
				chapter 3.7.1 and reference circuit in Figure 10.
			6.	Updated reference circuit of (U)SIM interface in
				Figure 17&18.
			7.	Updated reference circuit of USB interface in Figure
				19.
			8.	Updated PCM mode in Chapter 3.12.
			9.	Updated USB_BOOT reference circuit in Chapter
				3.20.
		Annice ZHANG/	10.	Added SD card interface in Chapter 3.13.
1.5	2018-03-05	Lyndon LIU/	11.	Updated module operating frequencies in Table 26.
		Frank WANG	12.	Updated EC21 series modules current consumption
				in Chapter 6.5.
			13.	Updated EC21 series modules conducted RF
				receiving sensitivity in Chapter 6.6.
			14.	Added thermal consideration description in Chapter
				6.8.
			15.	Updated dimension tolerance information in
				Chapter 7.
			16.	Added storage temperature range in Table 2 and
				Chapter 6.3.
			17.	Updated RF output power in Table 42.
			18.	Updated antenna requirements in Table 29.
			19.	Updated GPRS multi-slot classes in Table 55.
			20.	Updated storage information in Chapter 8.1

EC21_Hardware_Design

3 / 105

LTE Module Series

EC21 Hardware Design

Contents
About the Document.................................................................................................................................................	2
Contents.......................................................................................................................................................................	4
Table Index..................................................................................................................................................................	7
Figure Index.................................................................................................................................................................	9
1 Introduction...........................................................................................................................................................	11
1.1. Safety Information......................................................................................................................................	12
2 Product Concept..................................................................................................................................................	13
2.1. General Description...................................................................................................................................	13
2.2. Key Features..............................................................................................................................................	14
2.3. Functional Diagram....................................................................................................................................	17
2.4. Evaluation Board........................................................................................................................................	17
3 Application Interfaces........................................................................................................................................	18
3.1. General Description...................................................................................................................................	18
..............................................................................................................................................
3.2. Pin Description...........................................................................................................................................	19
3.3. Operating Modes........................................................................................................................................	28
3.4. Power Saving..............................................................................................................................................	29
3.4.1. Sleep Mode......................................................................................................................................	29
3.4.1.1. UART Application................................................................................................................	29
3.4.1.2. USB Application with USB Remote Wakeup Function.................................................	30
3.4.1.3. USB Application with USB Suspend/Resume and RI Function..................................	31
3.4.1.4. USB Application without USB Suspend Function..........................................................	31
3.4.2. Airplane Mode.................................................................................................................................	32
3.5. Power Supply..............................................................................................................................................	33
3.5.1. Power Supply Pins.........................................................................................................................	33
3.5.2. Decrease Voltage Drop.................................................................................................................	33
3.5.3. Reference Design for Power Supply...........................................................................................	34
3.5.4. Monitor the Power Supply.............................................................................................................	35
3.6. Turn on and off Scenarios........................................................................................................................	35
3.6.1. Turn on Module Using the PWRKEY..........................................................................................	35
3.6.2. Turn off Module...............................................................................................................................	37
3.6.2.1. Turn off Module Using the PWRKEY Pin........................................................................	37
3.6.2.2. Turn off Module Using AT Command...............................................................................	38
3.7. Reset the Module.......................................................................................................................................	38
3.8. (U)SIM Interface.........................................................................................................................................	40
3.9. USB Interface.............................................................................................................................................	42
3.10. UART Interfaces.......................................................................................................................................	44
3.11. PCM and I2C Interfaces.........................................................................................................................	46

EC21_Hardware_Design

4 / 105

	LTE Module Series
	EC21 Hardware Design
3.12. SD Card Interface....................................................................................................................................	48
3.13. ADC Interfaces.........................................................................................................................................	51
3.14. Network Status Indication......................................................................................................................	51
3.15. STATUS.....................................................................................................................................................	53
3.16. Behaviors of RI.........................................................................................................................................	53
3.17. SGMII Interface........................................................................................................................................	54
4 GNSS Receiver.....................................................................................................................................................	58
4.1. General Description...................................................................................................................................	58
4.2. GNSS Performance...................................................................................................................................	58
4.3. Layout Guidelines......................................................................................................................................	59
5 Antenna Interfaces..............................................................................................................................................	60
5.1. Main/Rx-diversity Antenna Interfaces.....................................................................................................	60
5.1.1. Pin Definition...................................................................................................................................	60
5.1.2. Operating Frequency.....................................................................................................................	60
5.1.3. Reference Design of RF Antenna Interface...............................................................................	61
5.1.4. Reference Design of RF Layout...................................................................................................	62
5.2. GNSS Antenna Interface..........................................................................................................................	64
5.3. Antenna Installation...................................................................................................................................	65
5.3.1. Antenna Requirement....................................................................................................................	65
5.3.2. Recommended RF Connector for Antenna Installation...........................................................	66
6 Electrical, Reliability and Radio Characteristics........................................................................................	68
6.1. Absolute Maximum Ratings.....................................................................................................................	68
6.2. Power Supply Ratings...............................................................................................................................	69
6.3. Operation and Storage Temperatures....................................................................................................	69
6.4. Current Consumption................................................................................................................................	70
6.5. RF Output Power.......................................................................................................................................	76
6.6. RF Receiving Sensitivity...........................................................................................................................	77
6.7. Electrostatic Discharge.............................................................................................................................	81
6.8. Thermal Consideration..............................................................................................................................	81
7 Mechanical Dimensions.....................................................................................................................................	84
7.1. Mechanical Dimensions of the Module..................................................................................................	84
7.2. Recommended Footprint..........................................................................................................................	86
7.3. Design Effect Drawings of the Module...................................................................................................	87
8 Storage, Manufacturing and Packaging........................................................................................................	88
8.1. Storage........................................................................................................................................................	88
8.2. Manufacturing and Soldering...................................................................................................................	89
8.3. Packaging....................................................................................................................................................	90
9 Appendix A References.....................................................................................................................................	91
10 Appendix B GPRS Coding Schemes...........................................................................................................	95
11 Appendix C GPRS Multi-slot Classes.........................................................................................................	96

EC21_Hardware_Design

5 / 105

LTE Module Series

EC21 Hardware Design

12 Appendix D EDGE Modulation and Coding Schemes............................................................................

98

EC21_Hardware_Design

6 / 105

LTE Module Series

EC21 Hardware Design

Table Index
TABLE 1: FREQUENCY BANDS OF EC21 SERIES MODULE................................................................................		13
TABLE 2: KEY FEATURES OF EC21 MODULE..........................................................................................................		14
TABLE 3: I/O PARAMETERS DEFINITION...................................................................................................................		19
TABLE 4: PIN DESCRIPTION.........................................................................................................................................		19
TABLE 5: OVERVIEW OF OPERATING MODES........................................................................................................		28
TABLE 6: VBAT AND GND PINS....................................................................................................................................		33
TABLE 7: PIN DEFINITION OF PWRKEY.....................................................................................................................		35
TABLE 8: PIN DEFINITION OF RESET_N...................................................................................................................		38
TABLE 9: PIN DEFINITION OF THE (U)SIM INTERFACE.........................................................................................		40
TABLE 10: PIN DESCRIPTION OF USB INTERFACE...............................................................................................		42
TABLE 11: PIN DEFINITION OF MAIN UART INTERFACE.......................................................................................		44
TABLE 12: PIN DEFINITION OF DEBUG UART INTERFACE..................................................................................		44
TABLE 13: LOGIC LEVELS OF DIGITAL I/O................................................................................................................		45
TABLE 14: PIN DEFINITION OF PCM AND I2C INTERFACES................................................................................		47
TABLE 15: PIN DEFINITION OF SD CARD INTERFACE..........................................................................................		49
TABLE 16: PIN DEFINITION OF ADC INTERFACES.................................................................................................		51
TABLE 17: CHARACTERISTIC OF ADC.......................................................................................................................		51
TABLE 18: PIN DEFINITION OF NETWORK CONNECTION STATUS/ACTIVITY INDICATOR..........................		52
TABLE 19: WORKING STATE OF NETWORK CONNECTION STATUS/ACTIVITY INDICATOR........................		52
TABLE 20: PIN DEFINITION OF STATUS.....................................................................................................................		53
TABLE 21: BEHAVIOR OF RI.........................................................................................................................................		54
TABLE 22: PIN DEFINITION OF THE SGMII INTERFACE........................................................................................		54
TABLE 23: PIN DEFINITION OF WIRELESS CONNECTIVITY INTERFACES.......................
TABLE 24: PIN DEFINITION OF USB_BOOT INTERFACE.......................................................................................		56
TABLE 25: GNSS PERFORMANCE..............................................................................................................................		58
TABLE 26: PIN DEFINITION OF RF ANTENNAS........................................................................................................		60
TABLE 27: MODULE OPERATING FREQUENCIES..................................................................................................		60
TABLE 28: PIN DEFINITION OF GNSS ANTENNA INTERFACE..............................................................................		64
TABLE 29: GNSS FREQUENCY....................................................................................................................................		64
TABLE 30: ANTENNA REQUIREMENTS.......................................................................................................................		65
TABLE 31: ABSOLUTE MAXIMUM RATINGS..............................................................................................................		68
TABLE 32: POWER SUPPLY RATINGS.......................................................................................................................		69
TABLE 33: OPERATION AND STORAGE TEMPERATURES...................................................................................		69
TABLE 34: EC21-E CURRENT CONSUMPTION........................................................................................................		70
TABLE 35: EC21-A CURRENT CONSUMPTION........................................................................................................		72
TABLE 36: EC21-V CURRENT CONSUMPTION........................................................................................................		73
TABLE 37: EC21-AUT CURRENT CONSUMPTION...................................................................................................		73
TABLE 38: EC21-AUV CURRENT CONSUMPTION...................................................................................................		74
TABLE 39: EC21-J CURRENT CONSUMPTION.........................................................................................................		75
TABLE 40: EC21-KL CURRENT CONSUMPTION......................................................................................................		76
TABLE 41: GNSS CURRENT CONSUMPTION OF EC21 SERIES MODULE.......................................................		76

EC21_Hardware_Design

7 / 105

	LTE Module Series
	EC21 Hardware Design
TABLE 42: RF OUTPUT POWER...................................................................................................................................	77
TABLE 43: EC21-E CONDUCTED RF RECEIVING SENSITIVITY...........................................................................	77
TABLE 44: EC21-A CONDUCTED RF RECEIVING SENSITIVITY...........................................................................	78
TABLE 45: EC21-V CONDUCTED RF RECEIVING SENSITIVITY...........................................................................	78
TABLE 46: EC21-AUT CONDUCTED RF RECEIVING SENSITIVITY......................................................................	78
TABLE 47: EC21-KL CONDUCTED RF RECEIVING SENSITIVITY.........................................................................	79
TABLE 48: EC21-J CONDUCTED RF RECEIVING SENSITIVITY............................................................................	79
TABLE 49: EC21-AUV CONDUCTED RF RECEIVING SENSITIVITY.....................................................................	79
TABLE 50: EC21-AU CONDUCTED RF RECEIVING SENSITIVITY........................................................................	80
TABLE 51: ELECTROSTATIC DISCHARGE CHARACTERISTICS..........................................................................	81
TABLE 52: RELATED DOCUMENTS.............................................................................................................................	91
TABLE 53: TERMS AND ABBREVIATIONS..................................................................................................................	91
TABLE 54: DESCRIPTION OF DIFFERENT CODING SCHEMES..........................................................................	95
TABLE 55: GPRS MULTI-SLOT CLASSES..................................................................................................................	96
TABLE 56: EDGE MODULATION AND CODING SCHEMES...................................................................................	98

EC21_Hardware_Design

8 / 105

LTE Module Series

EC21 Hardware Design

Figure Index
FIGURE 1: FUNCTIONAL DIAGRAM............................................................................................................................		17
FIGURE 2: PIN ASSIGNMENT (TOP VIEW).................................................................................
FIGURE 3: SLEEP MODE APPLICATION VIA UART.................................................................................................		29
FIGURE 4: SLEEP MODE APPLICATION WITH USB REMOTE WAKEUP...........................................................		30
FIGURE 5: SLEEP MODE APPLICATION WITH RI....................................................................................................		31
FIGURE 6: SLEEP MODE APPLICATION WITHOUT SUSPEND FUNCTION......................................................		32
FIGURE 7: POWER SUPPLY LIMITS DURING BURST TRANSMISSION.............................................................		33
FIGURE 8: STAR STRUCTURE OF THE POWER SUPPLY.....................................................................................		34
FIGURE 9: REFERENCE CIRCUIT OF POWER SUPPLY........................................................................................		35
FIGURE 10: TURN ON THE MODULE BY USING DRIVING CIRCUIT..................................................................		36
FIGURE 11: TURN ON THE MODULE BY USING BUTTON.....................................................................................		36
FIGURE 12: TIMING OF TURNING ON MODULE......................................................................................................		37
FIGURE 13: TIMING OF TURNING OFF MODULE....................................................................................................		38
FIGURE 14: REFERENCE CIRCUIT OF RESET_N BY USING DRIVING CIRCUIT............................................		39
FIGURE 15: REFERENCE CIRCUIT OF RESET_N BY USING BUTTON.............................................................		39
FIGURE 16: TIMING OF RESETTING MODULE........................................................................................................		40
FIGURE 17: REFERENCE CIRCUIT OF (U)SIM INTERFACE WITH AN 8-PIN (U)SIM CARD CONNECTOR
.....................................................................................................................................................................................		41
FIGURE 18: REFERENCE CIRCUIT OF (U)SIM INTERFACE WITH A 6-PIN (U)SIM CARD CONNECTOR..		41
FIGURE 19: REFERENCE CIRCUIT OF USB APPLICATION..................................................................................		43
FIGURE 20: REFERENCE CIRCUIT WITH TRANSLATOR CHIP............................................................................		45
FIGURE 21: REFERENCE CIRCUIT WITH TRANSISTOR CIRCUIT......................................................................		46
FIGURE 22: PRIMARY MODE TIMING.........................................................................................................................		47
FIGURE 23: AUXILIARY MODE TIMING......................................................................................................................		47
FIGURE 24: REFERENCE CIRCUIT OF PCM APPLICATION WITH AUDIO CODEC.........................................		48
FIGURE 25: REFERENCE CIRCUIT OF SD CARD...................................................................................................		50
FIGURE 26: REFERENCE CIRCUIT OF THE NETWORK INDICATOR.................................................................		52
FIGURE 27: REFERENCE CIRCUITS OF STATUS....................................................................................................		53
FIGURE 28: SIMPLIFIED BLOCK DIAGRAM FOR ETHERNET APPLICATION...................................................		55
FIGURE 29: REFERENCE CIRCUIT OF SGMII INTERFACE WITH PHY AR8033 APPLICATION...................		56
FIGURE 30: REFERENCE CIRCUIT OF WIRELESS CONNECTIVITY INTERFACES WITH FC20 MODULE
FIGURE 31: REFERENCE CIRCUIT OF USB_BOOT INTERFACE........................................................................		57
FIGURE 32: REFERENCE CIRCUIT OF RF ANTENNA INTERFACE.....................................................................		62
FIGURE 33: MICROSTRIP LINE DESIGN ON A 2-LAYER PCB..............................................................................		62
FIGURE 34: COPLANAR WAVEGUIDE LINE DESIGN ON A 2-LAYER PCB........................................................		63
FIGURE 35: COPLANAR WAVEGUIDE LINE DESIGN ON A 4-LAYER PCB (LAYER 3 AS REFERENCE
GROUND)..................................................................................................................................................................		63
FIGURE 36: COPLANAR WAVEGUIDE LINE DESIGN ON A 4-LAYER PCB (LAYER 4 AS REFERENCE
GROUND)..................................................................................................................................................................		63
FIGURE 37: REFERENCE CIRCUIT OF GNSS ANTENNA......................................................................................		65

EC21_Hardware_Design

9 / 105

LTE Module Series
EC21 Hardware Design
FIGURE 38: DIMENSIONS OF THE U.FL-R-SMT CONNECTOR (UNIT: MM)......................................................	66
FIGURE 39: MECHANICALS OF U.FL-LP CONNECTORS......................................................................................	67
FIGURE 40: SPACE FACTOR OF MATED CONNECTOR (UNIT: MM)...................................................................	67
FIGURE 41: REFERENCED HEATSINK DESIGN (HEATSINK AT THE TOP OF THE MODULE).....................	82
FIGURE 42: REFERENCED HEATSINK DESIGN (HEATSINK AT THE BOTTOM OF CUSTOMERS’ PCB)...	82
FIGURE 43: MODULE TOP AND SIDE DIMENSIONS...............................................................................................	84
FIGURE 44: MODULE BOTTOM DIMENSIONS (BOTTOM VIEW)..........................................................................	85
FIGURE 45: RECOMMENDED FOOTPRINT (TOP VIEW)........................................................................................	86
FIGURE 46: TOP VIEW OF THE MODULE..................................................................................................................	87
FIGURE 47: BOTTOM VIEW OF THE MODULE.........................................................................................................	87
FIGURE 48: REFLOW SOLDERING THERMAL PROFILE.......................................................................................	89
FIGURE 49: TAPE AND REEL SPECIFICATIONS......................................................................................................	90

EC21_Hardware_Design

10 / 105

LTE Module Series

EC21 Hardware Design

1 Introduction

This document defines the EC21 module and describes its air interface and hardware interface which are connected with customers’ applications.

This document can help customers quickly understand module interface specifications, electrical and mechanical details, as well as other related information of EC21 module. Associated with application note and user guide, customers can use EC21 module to design and set up mobile applications easily.

EC21_Hardware_Design

1-11 / 105

LTE Module Series

EC21 Hardware Design

1.1. Safety Information

The following safety precautions must be observed during all phases of the operation, such as usage, service or repair of any cellular terminal or mobile incorporating EC21 module. Manufacturers of the cellular terminal should send the following safety information to users and operating personnel, and incorporate these guidelines into all manuals supplied with the product. If not so, Quectel assumes no liability for the customers’ failure to comply with these precautions.

Full attention must be given to driving at all times in order to reduce the risk of an accident. Using a mobile while driving (even with a handsfree kit) causes distraction and can lead to an accident. You must comply with laws and regulations restricting the use of wireless devices while driving.

Switch off the cellular terminal or mobile before boarding an aircraft. Make sure it is switched off. The operation of wireless appliances in an aircraft is forbidden, so as to prevent interference with communication systems. Consult the airline staff about the use of wireless devices on boarding the aircraft, if your device offers an Airplane Mode which must be enabled prior to boarding an aircraft.

Switch off your wireless device when in hospitals,clinics or other health care facilities. These requests are desinged to prevent possible interference with sensitive medical equipment.

Cellular terminals or mobiles operating over radio frequency signal and cellular network cannot be guaranteed to connect in all conditions, for example no mobile fee or with an invalid (U)SIM card. While you are in this condition and need emergent help, please remember using emergency call. In order to make or receive a call, the cellular terminal or mobile must be switched on and in a service area with adequate cellular signal strength.

Your cellular terminal or mobile contains a transmitter and receiver. When it is ON, it receives and transmits radio frequency energy. RF interference can occur if it is used close to TV set, radio, computer or other electric equipment.

In locations with potentially explosive atmospheres, obey all posted signs to turn off wireless devices such as your phone or other cellular terminals. Areas with potentially explosive atmospheres include fuelling areas, below decks on boats, fuel or chemical transfer or storage facilities, areas where the air contains chemicals or particles such as grain, dust or metal powders, etc.

EC21_Hardware_Design

1-12 / 105

LTE Module Series

EC21 Hardware Design

2 Product Concept

2.1. General Description

EC21 is a series of LTE-FDD/LTE-TDD/WCDMA/GSM wireless communication module with receive diversity. It provides data connectivity on LTE-FDD, LTE-TDD, DC-HSDPA, HSPA+, HSDPA, HSUPA, WCDMA, EDGE and GPRS networks. It also provides GNSS1) and voice functionality2) for customers’ specific applications. EC21 contains nine variants: EC21-E, EC21-A, EC21-V, EC21-AU, EC21-AUT, EC21-AUV, EC21-J, EC21-KL and EC20-CEL. Customers can choose a dedicated type based on the region or operator. The following table shows the frequency bands of EC21 series module.

Table 1: Frequency Bands of EC21 Series Module

	Modules2)	LTE Bands	UMTS Bands	GSM	Rx-	GNSS1)
					diversity
	EC21-E	FDD: B1/B3/B5/B7/B8/B20	WCDMA:	900/1800	Y
			B1/B5/B8
	EC21-A	FDD: B2/B4/B12	WCDMA:	N	Y	GPS,
			B2/B4/B5
						GLONASS,
	EC21-V
		FDD: B4/B13	N	N	Y	BeiDou/
						Compass,
		FDD: B1/B2/B3/B4/B5/B7/B8/	WCDMA:	850/900/
						Galileo,
	EC21-AU3)	B28			Y
			B1/B2/B5/B8	1800/1900		QZSS
		TDD: B40
	EC21-AUT	FDD: B1/B3/B5/B7/B28	WCDMA:	N	Y
			B1/B5
	EC21-AUV	FDD: B1/B3/B5/B8/B28	B1/B5/B8	N	Y	N
	EC21-J	FDD: B1/B3/B8/B18/B19/B26	N	N	Y	N
	EC21-KL	FDD: B1/B3/B5/B7/B8	N	N	Y	N
	EC20-CEL	FDD: B1/B3/B5	N	N	N	N

EC21_Hardware_Design

2-13 / 105

LTE Module Series

EC21 Hardware Design

NOTES

1. 1) GNSS function is optional.

2. 2) EC21 series module (EC21-E, EC21-A, EC21-V, EC21-AU, EC21-AUT, EC21-AUV, EC21-J, EC21-KL and EC20-CEL) contains Telematics version and Data-only version. Telematics version supports voice and data functions, while Data-only version only supports data function.

3. 3) B2 band on EC21-AU module does not support Rx-diversity.

4.Y = Supported. N = Not supported.

With a compact profile of 29.0mm × 32.0mm × 2.4mm, EC21 can meet almost all requirements for M2M applications such as automotive, metering, tracking system, security, router, wireless POS, mobile computing device, PDA phone, tablet PC, etc.

EC21 is an SMD type module which can be embedded into applications through its 144-pin pads, including 80 LCC signal pads and 64 other pads.

2.2. Key Features

The following table describes the detailed features of EC21 module.

Table 2: Key Features of EC21 Module

	Features	Details
	Power Supply	Supply voltage: 3.3V~4.3V
		Typical supply voltage: 3.8V
		Class 4 (33dBm±2dB) for GSM850
		Class 4 (33dBm±2dB) for GSM900
		Class 1 (30dBm±2dB) for DCS1800
		Class 1 (30dBm±2dB) for PCS1900
		Class E2 (27dBm±3dB) for GSM850 8-PSK
	Transmitting Power	Class E2 (27dBm±3dB) for GSM900 8-PSK
		Class E2 (26dBm±3dB) for DCS1800 8-PSK
		Class E2 (26dBm±3dB) for PCS1900 8-PSK
		Class 3 (24dBm+1/-3dB) for WCDMA bands
		Class 3 (23dBm±2dB) for LTE-FDD bands
		Class 3 (23dBm±2dB) for LTE-TDD bands
		Support up to non-CA Cat 1 FDD and TDD
	LTE Features	Support 1.4MHz~20MHz RF bandwidth
		Support MIMO in DL direction
		LTE-FDD: Max 10Mbps (DL)/5Mbps (UL)

EC21_Hardware_Design

2-14 / 105

LTE Module Series

EC21 Hardware Design

		LTE-TDD: Max 8.96Mbps (DL)/3.1Mbps (UL)
		Support 3GPP R8 DC-HSDPA, HSPA+, HSDPA, HSUPA and WCDMA
		Support QPSK, 16-QAM and 64-QAM modulation
	UMTS Features	DC-HSDPA: Max 42Mbps (DL)
		HSUPA: Max 5.76Mbps (UL)
		WCDMA: Max 384Kbps (DL)/384Kbps (UL)
		GPRS:
		Support GPRS multi-slot class 33 (33 by default)
		Coding scheme: CS-1, CS-2, CS-3 and CS-4
		Max 107Kbps (DL)/85.6Kbps (UL)
		EDGE:
	GSM Features	Support EDGE multi-slot class 33 (33 by default)
		Support GMSK and 8-PSK for different MCS (Modulation and Coding
		Scheme)
		Downlink coding schemes: CS 1-4 and MCS 1-9
		Uplink coding schemes: CS 1-4 and MCS 1-9
		Max 296Kbps (DL)/ 236.8Kbps (UL)
		Support TCP/UDP/PPP/FTP/HTTP/NTP/PING/QMI/ CMUX*/HTTPS*/
		SMTP*/ MMS*/FTPS*/SMTPS*/SSL*/FILE* protocols
	Internet Protocol Features	Support PAP (Password Authentication Protocol) and CHAP (Challenge
		Handshake Authentication Protocol) protocols which are usually used for
		PPP connections
		Text and PDU mode
	SMS	Point to point MO and MT
		SMS cell broadcast
		SMS storage: ME by default
	(U)SIM Interface	Support USIM/SIM card: 1.8V, 3.0V
		Support one digital audio interface: PCM interface
		GSM: HR/FR/EFR/AMR/AMR-WB
	Audio Features	WCDMA: AMR/AMR-WB
		LTE: AMR/AMR-WB
		Support echo cancellation and noise suppression
		Used for audio function with external codec
		Support 8-bit A-law*, μ-law* and 16-bit linear data formats
	PCM Interface	Support long frame synchronization and short frame synchronization
		Support master and slave modes, but must be the master in long frame
		synchronization
		Compliant with USB 2.0 specification (slave only); the data transfer rate
		can reach up to 480Mbps
	USB Interface	Used for AT command communication, data transmission, GNSS NMEA
		output, software debugging, firmware upgrade and voice over USB*
		Support USB serial drivers for: Windows XP, Windows Vista, Windows

EC21_Hardware_Design

2-15 / 105

LTE Module Series

EC21 Hardware Design

			7/8/8.1/10, Windows CE 5.0/6.0/7.0*, Linux 2.6/3.x/4.1,
			Android 4.x/5.x/6.x/7.x
			Main UART:
			Used for AT command communication and data transmission
			Baud rates reach up to 921600bps, 115200bps by default
	UART Interface		Support RTS and CTS hardware flow control
			Debug UART:
			Used for Linux console and log output
			115200bps baud rate
	SD Card Interface		Support SD 3.0 protocol
	SGMII Interface		Support 10/100/1000Mbps Ethernet connectivity
	Rx-diversity		Support LTE/WCDMA Rx-diversity
	GNSS Features		Gen8C Lite of Qualcomm
			Protocol: NMEA 0183
	AT Commands		Compliant with 3GPP TS 27.007, 27.005 and Quectel enhanced AT
			commands
	Network Indication		Two pins including NET_MODE and NET_STATUS to indicate network
			connectivity status
	Antenna Interface		Including main antenna interface (ANT_MAIN), Rx-diversity antenna
			interface (ANT_DIV) and GNSS antenna interface (ANT_GNSS)
	Physical Characteristics		Size: (29.0±0.15)mm × (32.0±0.15)mm × (2.4±0.2)mm
			Weight: approx. 4.9g
			Operation temperature range: -35°C ~ +75°C1)
	Temperature Range		Extended temperature range: -40°C ~ +85°C2)
			Storage temperature range: -40°C ~ +90°C
	Firmware Upgrade		USB interface and DFOTA*
	RoHS		All hardware components are fully compliant with EU RoHS directive
	NOTES
1.		1) Within operating temperature range, the module is 3GPP compliant.
2.		2) Within extended temperature range, the module remains the ability to establish and maintain a
		voice, SMS, data transmission, emergency call, etc. There is no unrecoverable malfunction. There
		are also no effects on radio spectrum and no harm to radio network. Only one or more parameters

like Pout might reduce in their value and exceed the specified tolerances. When the temperature returns to normal operating temperature levels, the module will meet 3GPP specifications again.

3.“*” means under development.

EC21_Hardware_Design

2-16 / 105

LTE Module Series

EC21 Hardware Design

2.3. Functional Diagram

The following figure shows a block diagram of EC21 and illustrates the major functional parts.

Power management

Baseband

DDR+NAND flash

Radio frequency

Peripheral interfaces

Figure 1: Functional Diagram

2.4. Evaluation Board

In order to help customers develop applications with EC21, Quectel supplies an evaluation board (EVB), USB to RS-232 converter cable, earphone, antenna and other peripherals to control or test the module.

EC21_Hardware_Design

2-17 / 105

LTE Module Series

EC21 Hardware Design

3 Application Interfaces

3.1. General Description

EC21 is equipped with 80 LCC pads plus 64 LGA pads that can be connected to cellular application platform. Sub-interfaces included in these pads are described in detail in the following chapters:

Power supply

(U)SIM interface

USB interface

UART interfaces

PCM and I2C interfaces

SD card interface

ADC interfaces

Status indication

SGMII interface

Wireless connectivity interfaces

USB_BOOT interface

EC21_Hardware_Design

3-18 / 105

LTE Module Series

EC21 Hardware Design

3.2. Pin Description

The following tables show the pin definition of EC21 module.

Table 3: I/O Parameters Definition

Type	Description
IO	Bidirectional
DI	Digital input
DO	Digital output
PI	Power input
PO	Power output
AI	Analog input
AO	Analog output
OD	Open drain

Table 4: Pin Description

Power Supply

	Pin Name	Pin No.	I/O	Description	DC Characteristics	Comment
				Power supply for	Vmax=4.3V	It must be able to
	VBAT_BB	59, 60	PI	module’s baseband	Vmin=3.3V	provide sufficient current
				part	Vnorm=3.8V	up to 0.8A.
					Vmax=4.3V	It must be able to
				Power supply for		provide sufficient current
	VBAT_RF	57, 58	PI		Vmin=3.3V
				module’s RF part		up to 1.8A in a burst
					Vnorm=3.8V
						transmission.
						Power supply for
	VDD_EXT	7	PO	Provide 1.8V for	Vnorm=1.8V	external GPIO’s pull-up
				external circuit	IOmax=50mA	circuits.
						If unused, keep it open.
	GND	8, 9, 19,		Ground
		22, 36, 46,

EC21_Hardware_Design

3-19 / 105

						LTE Module Series
						EC21 Hardware Design
		48, 50~54,
		56, 72,
		85~112
	Turn on/off
	Pin Name	Pin No.	I/O	Description	DC Characteristics	Comment
					VIHmax=2.1V	The output voltage is
				Turn on/off the		0.8V because of the
	PWRKEY	21	DI		VIHmin=1.3V
				module		diode drop in the
					VILmax=0.5V
						Qualcomm chipset.
				Reset signal of the	VIHmax=2.1V	If unused, keep it
	RESET_N	20	DI		VIHmin=1.3V
				module		open.
					VILmax=0.5V
	Status Indication
	Pin Name	Pin No.	I/O	Description	DC Characteristics	Comment
				Indicate the module	The drive current	Require external
	STATUS	61	OD		should be less than	pull-up. If unused,
				operating status
					0.9mA.	keep it open.
						1.8V power domain.
				Indicate the module	VOHmin=1.35V	It cannot be pulled up
	NET_MODE	5	DO	network registration		before startup.
					VOLmax=0.45V
				mode		If unused, keep it
						open.
	NET_			Indicate the module	VOHmin=1.35V	1.8V power domain.
		6	DO	network activity		If unused, keep it
	STATUS				VOLmax=0.45V
				status		open.
	USB Interface
	Pin Name	Pin No.	I/O	Description	DC Characteristics	Comment
					Vmax=5.25V	Typical: 5.0V
	USB_VBUS	71	PI	USB detection	Vmin=3.0V	If unused, keep it
					Vnorm=5.0V	open.
					Compliant with USB	Require differential
				USB differential data		impedance of 90Ω.
	USB_DP	69	IO		2.0 standard
				bus (+)		If unused, keep it
					specification.
						open.
					Compliant with USB	Require differential
				USB differential data		impedance of 90Ω.
	USB_DM	70	IO		2.0 standard
				bus (-)		If unused, keep it
					specification.
						open.

EC21_Hardware_Design

3-20 / 105

						LTE Module Series
						EC21 Hardware Design
	(U)SIM Interface
	Pin Name	Pin No.	I/O Description		DC Characteristics	Comment
	USIM_GND	10		Specified ground for
				(U)SIM card
					For 1.8V (U)SIM:
					Vmax=1.9V
					Vmin=1.7V
				Power supply for		Either 1.8V or 3.0V is
	USIM_VDD	14	PO		For 3.0V (U)SIM:	supported by the
				(U)SIM card
					Vmax=3.05V	module automatically.
					Vmin=2.7V
					IOmax=50mA
					For 1.8V (U)SIM:
					VILmax=0.6V
					VIHmin=1.2V
					VOLmax=0.45V
				Data signal of	VOHmin=1.35V
	USIM_DATA	15	IO
				(U)SIM card
					For 3.0V (U)SIM:
					VILmax=1.0V
					VIHmin=1.95V
					VOLmax=0.45V
					VOHmin=2.55V
					For 1.8V (U)SIM:
					VOLmax=0.45V
				Clock signal of	VOHmin=1.35V
	USIM_CLK	16	DO
				(U)SIM card
					For 3.0V (U)SIM:
					VOLmax=0.45V
					VOHmin=2.55V
					For 1.8V (U)SIM:
					VOLmax=0.45V
	USIM_RST	17	DO	Reset signal of	VOHmin=1.35V
				(U)SIM card	For 3.0V (U)SIM:
					VOLmax=0.45V
					VOHmin=2.55V
					VILmin=-0.3V	1.8V power domain.
	USIM_			(U)SIM card	VILmax=0.6V
		13	DI			If unused, keep it
	PRESENCE			insertion detection	VIHmin=1.2V
						open.
					VIHmax=2.0V

EC21_Hardware_Design

3-21 / 105

						LTE Module Series
						EC21 Hardware Design
	Main UART Interface
	Pin Name	Pin No.	I/O	Description	DC Characteristics	Comment
					VOLmax=0.45V	1.8V power domain.
	RI	62	DO	Ring indicator		If unused, keep it
					VOHmin=1.35V
						open.
				Data carrier	VOLmax=0.45V	1.8V power domain.
	DCD	63	DO			If unused, keep it
				detection	VOHmin=1.35V
						open.
					VOLmax=0.45V	1.8V power domain.
	CTS	64	DO	Clear to send		If unused, keep it
					VOHmin=1.35V
						open.
					VILmin=-0.3V	1.8V power domain.
					VILmax=0.6V
	RTS	65	DI	Request to send		If unused, keep it
					VIHmin=1.2V
						open.
					VIHmax=2.0V
						1.8V power domain.
					VILmin=-0.3V	Pulled up by default.
	DTR	66	DI	Data terminal ready,	VILmax=0.6V	Low level wakes up
				sleep mode control	VIHmin=1.2V	the module.
					VIHmax=2.0V	If unused, keep it
						open.
					VOLmax=0.45V	1.8V power domain.
	TXD	67	DO	Transmit data		If unused, keep it
					VOHmin=1.35V
						open.
					VILmin=-0.3V	1.8V power domain.
					VILmax=0.6V
	RXD	68	DI	Receive data		If unused, keep it
					VIHmin=1.2V
						open.
					VIHmax=2.0V
	Debug UART Interface
	Pin Name	Pin No.	I/O	Description	DC Characteristics	Comment
					VOLmax=0.45V	1.8V power domain.
	DBG_TXD	12	DO	Transmit data		If unused, keep it
					VOHmin=1.35V
						open.
					VILmin=-0.3V	1.8V power domain.
					VILmax=0.6V
	DBG_RXD	11	DI	Receive data		If unused, keep it
					VIHmin=1.2V
						open.
					VIHmax=2.0V
	ADC Interface
	Pin Name	Pin No.	I/O	Description	DC Characteristics	Comment

EC21_Hardware_Design

3-22 / 105

							LTE Module Series
							EC21 Hardware Design
				General purpose		Voltage range:	If unused, keep it
	ADC0	45	AI	analog to digital
						0.3V to VBAT_BB	open.
				converter
				General purpose		Voltage range:	If unused, keep it
	ADC1	44	AI	analog to digital
						0.3V to VBAT_BB	open.
				converter
	PCM Interface
	Pin Name	Pin No.	I/O	Description		DC Characteristics	Comment
						VILmin=-0.3V	1.8V power domain.
						VILmax=0.6V
	PCM_IN	24	DI	PCM data input			If unused, keep it
						VIHmin=1.2V
							open.
						VIHmax=2.0V
						VOLmax=0.45V	1.8V power domain.
	PCM_OUT	25	DO	PCM data output			If unused, keep it
						VOHmin=1.35V
							open.
						VOLmax=0.45V	1.8V power domain.
							In master mode, it is
						VOHmin=1.35V
				PCM data	frame		an output signal.
						VILmin=-0.3V
	PCM_SYNC	26	IO	synchronization			In slave mode, it is an
						VILmax=0.6V
				signal			input signal.
						VIHmin=1.2V
							If unused, keep it
						VIHmax=2.0V
							open.
						VOLmax=0.45V	1.8V power domain.
							In master mode, it is
						VOHmin=1.35V
							an output signal.
						VILmin=-0.3V
	PCM_CLK	27	IO	PCM clock			In slave mode, it is an
						VILmax=0.6V
							input signal.
						VIHmin=1.2V
							If unused, keep it
						VIHmax=2.0V
							open.
	I2C Interface
	Pin Name	Pin No.	I/O	Description		DC Characteristics	Comment
							External pull-up
				I2C serial clock.			resistor is required.
	I2C_SCL	41	OD	Used for external			1.8V only.
				codec			If unused, keep it
							open.
				I2C serial data.			External pull-up
							resistor is required.
	I2C_SDA	42	OD	Used for external
							1.8V only.
				codec
							If unused, keep it

EC21_Hardware_Design

3-23 / 105

						LTE Module Series
						EC21 Hardware Design
						open.
	SD Card Interface
	Pin Name	Pin No.	I/O Description		DC Characteristics Comment
					1.8V signaling:
					VOLmax=0.45V
					VOHmin=1.4V
					VILmin=-0.3V	SDIO signal level can
					VILmax=0.58V
						be selected according
					VIHmin=1.27V
						to SD card supported
					VIHmax=2.0V
	SDC2_			SD card SDIO bus		level, more details
		28	IO
	DATA3			DATA3		please refer to SD 3.0
					3.0V signaling:
						protocol.
					VOLmax=0.38V
						If unused, keep it
					VOHmin=2.01V
						open.
					VILmin=-0.3V
					VILmax=0.76V
					VIHmin=1.72V
					VIHmax=3.34V
					1.8V signaling:
					VOLmax=0.45V
					VOHmin=1.4V
					VILmin=-0.3V	SDIO signal level can
					VILmax=0.58V
						be selected according
					VIHmin=1.27V
						to SD card supported
					VIHmax=2.0V
	SDC2_			SD card SDIO bus		level, more details
		29	IO
	DATA2			DATA2		please refer to SD 3.0
					3.0V signaling:
						protocol.
					VOLmax=0.38V
						If unused, keep it
					VOHmin=2.01V
						open.
					VILmin=-0.3V
					VILmax=0.76V
					VIHmin=1.72V
					VIHmax=3.34V
					1.8V signaling:	SDIO signal level can
					VOLmax=0.45V
						be selected according
					VOHmin=1.4V
						to SD card supported
					VILmin=-0.3V
	SDC2_			SD card SDIO bus		level, more details
		30	IO		VILmax=0.58V
	DATA1			DATA1		please refer to SD 3.0
					VIHmin=1.27V
						protocol.

VIHmax=2.0V	If unused, keep it
3.0V signaling:	open.

EC21_Hardware_Design

3-24 / 105

LTE Module Series

EC21 Hardware Design

				VOLmax=0.45V
				VOHmin=1.4V
				VILmin=-0.3V	SDIO signal level can
				VILmax=0.58V
					be selected according
				VIHmin=1.27V
					to SD card supported
				VIHmax=2.0V
SDC2_			SD card SDIO bus		level, more details
	31	IO
DATA0			DATA0		please refer to SD 3.0
				3.0V signaling:
					protocol.
				VOLmax=0.38V
					If unused, keep it
				VOHmin=2.01V
					open.
				VILmin=-0.3V
				VILmax=0.76V
				VIHmin=1.72V
				VIHmax=3.34V
				1.8V signaling:	SDIO signal level can
					be selected according
				VOLmax=0.45V
					to SD card supported
				VOHmin=1.4V
			SD card SDIO bus		level, more details
SDC2_CLK	32	DO
			clock		please refer to SD 3.0
				3.0V signaling:
					protocol.
				VOLmax=0.38V
					If unused, keep it
				VOHmin=2.01V
					open.
				1.8V signaling:
				VOLmax=0.45V
				VOHmin=1.4V
				VILmin=-0.3V	SDIO signal level can
				VILmax=0.58V
					be selected according
				VIHmin=1.27V
					to SD card supported
				VIHmax=2.0V
			SD card SDIO bus		level, more details
SDC2_CMD	33	IO
			command		please refer to SD 3.0
				3.0V signaling:

	VOLmax=0.38V	protocol.
	VOHmin=2.01V
	VILmin=-0.3V
	VILmax=0.76V
	VIHmin=1.72V
	VIHmax=3.34V
	1.8V signaling:
	VOLmax=0.38V	If unused, keep it
	VOHmin=2.01V
		open.
	VILmin=-0.3V
	VILmax=0.76V
	VIHmin=1.72V
	VIHmax=3.34V

EC21_Hardware_Design

3-25 / 105

						LTE Module Series
						EC21 Hardware Design
					VILmin=-0.3V	1.8V power domain.
	SD_INS_			SD card insertion	VILmax=0.6V
		23	DI			If unused, keep it
	DET			detect	VIHmin=1.2V
						open.
					VIHmax=2.0V
						1.8V/2.85V
						configurable. Cannot
	VDD_SDIO	34	PO	SD card SDIO bus	IOmax=50mA	be used for SD card
				pull-up power		power.
						If unused, keep it
						open.
	SGMII Interface
	Pin Name	Pin No.	I/O	Description	DC Characteristics Comment
					For 1.8V:
					VOLmax=0.45V	1.8V/2.85V power
					VOHmin=1.4V
						domain.
	EPHY_RST_N	119	DO	Ethernet PHY reset
						If unused, keep it
					For 2.85V:
						open.
					VOLmax=0.35V
					VOHmin=2.14V
					VILmin=-0.3V	1.8V power domain.
				Ethernet PHY	VILmax=0.6V
	EPHY_INT_N	120	DI			If unused, keep it
				interrupt	VIHmin=1.2V
						open.
					VIHmax=2.0V
					For 1.8V:
					VOLmax=0.45V
					VOHmin=1.4V
					VILmax=0.58V	1.8V/2.85V power
				SGMII MDIO	VIHmin=1.27V
	SGMII_					domain.
		121	IO	(Management Data
	MDATA					If unused, keep it
				Input/Output) data	For 2.85V:
						open.
					VOLmax=0.35V
					VOHmin=2.14V
					VILmax=0.71V
					VIHmin=1.78V
					For 1.8V:
					VOLmax=0.45V	1.8V/2.85V power
				SGMII MDIO	VOHmin=1.4V
	SGMII_					domain.
		122	DO	(Management Data
	MCLK					If unused, keep it
				Input/Output) clock	For 2.85V:
						open.
					VOLmax=0.35V

VOHmin=2.14V

EC21_Hardware_Design

3-26 / 105

						LTE Module Series
						EC21 Hardware Design
						Configurable power
						source.
						1.8V/2.85V power
	USIM2_VDD	128	PO	SGMII MDIO pull-up		domain.
				power source		External pull-up for
						SGMII MDIO pins.
						If unused, keep it
						open.
	SGMII_TX_M	123	AO	SGMII transmission		If unused, keep it
				- minus		open.
	SGMII_TX_P	124	AO	SGMII transmission		If unused, keep it
				- plus		open.
	SGMII_RX_P	125	AI	SGMII receiving		If unused, keep it
				- plus		open.
	SGMII_RX_M	126	AI	SGMII receiving		If unused, keep it
				- minus		open.
	RF Interface
	Pin Name	Pin No.	I/O	Description	DC Characteristics	Comment
				Diversity antenna		50Ω impedance
	ANT_DIV	35	AI			If unused, keep it
				pad
						open.
	ANT_MAIN	49	IO	Main antenna pad		50Ω impedance
						50Ω impedance
	ANT_GNSS	47	AI	GNSS antenna pad		If unused, keep it
						open.
	GPIO Pins
	Pin Name	Pin No.	I/O	Description	DC Characteristics	Comment
						1.8V power domain.
					VILmin=-0.3V	Cannot be pulled up
						before startup.
					VILmax=0.6V
	WAKEUP_IN	1	DI	Sleep mode control		Low level wakes up
					VIHmin=1.2V
						the module.
					VIHmax=2.0V
						If unused, keep it
						open.
						1.8V power domain.
					VILmin=-0.3V	Pull-up by default.
	W_DISABLE#	4	DI	Airplane mode	VILmax=0.6V	At low voltage level,
				control	VIHmin=1.2V	module can enter into
					VIHmax=2.0V	airplane mode.
						If unused, keep it

EC21_Hardware_Design

3-27 / 105

						LTE Module Series
						EC21 Hardware Design
						open.
				Application	VILmin=-0.3V	1.8V power domain.
					VILmax=0.6V
	AP_READY	2	DI	processor sleep		If unused, keep it
					VIHmin=1.2V
				state detection		open.
					VIHmax=2.0V
	USB_BOOT Interface
	Pin Name	Pin No.	I/O	Description	DC Characteristics	Comment
				Force the module to	VILmin=-0.3V	1.8V power domain.
	USB_BOOT	115	DI	enter into	VILmax=0.6V	Active high.
				emergency	VIHmin=1.2V	If unused, keep it
				download mode.	VIHmax=2.0V	open.
	RESERVED Pins
	Pin Name	Pin No.	I/O	Description	DC Characteristics	Comment
		3, 18, 23,
		43, 55,
	RESERVED	73~84,		Reserved		Keep these pins
		113, 114,				unconnected.
		116, 117,
		140-144.

NOTES

1.“*” means under development.

2.Pads 24~27 are multiplexing pins used for audio design on EC21 module and BT function on FC20 module.

3.3. Operating Modes

The table below briefly summarizes the various operating modes referred in the following chapters.

Table 5: Overview of Operating Modes

	Mode	Details
		Idle	Software is active. The module has registered on the network, and it is
	Normal		ready to send and receive data.
	Operation	Talk/Data	Network connection is ongoing. In this mode, the power consumption is
			decided by network setting and data transfer rate.

EC21_Hardware_Design

3-28 / 105

LTE Module Series

EC21 Hardware Design

	Minimum	AT+CFUN command can set the module to a minimum functionality mode without
	Functionality
		removing the power supply. In this case, both RF function and (U)SIM card will be invalid.
	Mode
	Airplane	AT+CFUN command or W_DISABLE# pin can set the module to airplane mode. In this
	Mode	case, RF function will be invalid.
		In this mode, the current consumption of the module will be reduced to the minimal level.
	Sleep Mode	During this mode, the module can still receive paging message, SMS, voice call and
		TCP/UDP data from the network normally.
	Power down	In this mode, the power management unit shuts down the power supply. Software is not
		active. The serial interface is not accessible. Operating voltage (connected to VBAT_RF
	Mode
		and VBAT_BB) remains applied.

3.4. Power Saving

3.4.1. Sleep Mode

EC21 is able to reduce its current consumption to a minimum value during the sleep mode. The following section describes power saving procedures of EC21 module.

3.4.1.1. UART Application

If the host communicates with module via UART interface, the following preconditions can let the module enter into sleep mode.

Execute AT+QSCLK=1 command to enable sleep mode.

Drive DTR to high level.

The following figure shows the connection between the module and the host.

Figure 3: Sleep Mode Application via UART

EC21_Hardware_Design

3-29 / 105

LTE Module Series

EC21 Hardware Design

Driving the host DTR to low level will wake up the module.

When EC21 has a URC to report, RI signal will wake up the host. Refer to Chapter 3.17 for details about RI behaviors.

AP_READY will detect the sleep state of the host (can be configured to high level or low level detection). Please refer to AT+QCFG="apready"* command for details.

NOTE

“*” means under development.

3.4.1.2. USB Application with USB Remote Wakeup Function

If the host supports USB suspend/resume and remote wakeup functions, the following three preconditions must be met to let the module enter into sleep mode.

Execute AT+QSCLK=1 command to enable sleep mode.

Ensure the DTR is held at high level or keep it open.

The host’s USB bus, which is connected with the module’s USB interface, enters into suspended state.

The following figure shows the connection between the module and the host.

Figure 4: Sleep Mode Application with USB Remote Wakeup

Sending data to EC21 through USB will wake up the module.

When EC21 has a URC to report, the module will send remote wake-up signals via USB bus so as to wake up the host.

EC21_Hardware_Design

3-30 / 105