Datasheet nRF402 Datasheet (Nordic VLSI)

PRODUCT SPECIFICATION

433MHz Single Chip RF Transmitter

FEATURES

• True single chip FSK transmitter

• Few external components required

• On chip UHF synthesiser

• No set up or configuration

• 20kbit/s data rate

• 2 channels

• Very low power consumption

• Standby mode

APPLICATIONS

• Alarm Systems

• Automatic Meter Reading (AMR)

• Keyless entry

• Home Automation

• Remote Control

• Surveillance

• Automotive

• Telemetry

nRF402

• Toys

• Wireless Communication

GENERAL DESCRIPTION

nRF402 is a true single chip UHF transmitter designed to operate in the 433MHz ISM
(Industrial, Scientific and Medical) frequency band. It features Frequency Shift
Keying (FSK) modulation capability. nRF402 operates at data rates up to 20kbits/s.
Transmit power can be adjusted to a maximum of +10dBm. Antenna interface is
differential and suited for low cost PCB antennas. nRF402 operates from a single 3V
DC supply and has a standby mode which makes power saving easy and efficient.
As a primary application, nRF402 is intended for UHF radio equipment in compliance
with the European Telecommunication Standard Institute (ETSI) specification
EN 300 220-1 V1.2.1.

QUICK REFERENCE DATA

Parameter Value Unit

Frequency, Channel#1/Channel#2 433.92 / 434.33 MHz
Modulation FSK
Frequency deviation

Max. RF output power @ 400Ω, 3V
Maximum bit rate 20 kbit/s
Supply voltage 2.7 – 3.6 V
Transmit supply current @ -10 dBm RF output power 8 mA
Standby supply current 8

±15

10 dBm

Table 1. nRF402 quick reference data

ORDERING INFORMATION

Type number Description Version

nRF402-IC 14 pin SSOIC A

nRF402-EVKIT Evaluation kit with nRF402 IC 1.0

Table 2. nRF402 ordering information

kHz

µA

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Revision: 2.1 Page 1 of 16 February 2000

PRODUCT SPECIFICATION

nRF402 Single Chip RF Transmitter

BLOCK DIAGRAM

CS

DIN

PWR_UP

7

9

13

REFERENCE

1

OSC

PLL

14

LOOP

FILTER

LPF

Figure 1. nRF402 block diagram with external components

PIN FUNCTIONS

Pin Name Pin function Description

1

XC1 Input Crystal oscillator input

2

VSS Ground Ground (0V)

3

VDD Power Power supply (+3V DC)

4

VCO1 Input External inductor for VCO

5

VCO2 Input External inductor for VCO

6

LPF Test Loop filter voltage test pin *

7

CS Input Channel selection

CS=“0” ⇒ 433.92MHz, (Channel#1)
CS=“1” ⇒ 434.33MHz, (Channel#2)

8

RF_PWR Input Transmit power setting

9

DIN Input Data input

10

ANT2 Output Antenna terminal

11

ANT1 Output Antenna terminal

12

VSS Ground Ground (0V)

13

PWR_UP Input Power on/off

PWR_UP = “1” ⇒ Power up (Transmit mode)
PWR_UP = “0” ⇒ Power down (Standby mode)

14

XC2 Output Crystal oscillator output

11

PAVCO

4

6

INDUCTOR

5

VCO

8

RF_PWR

ANT1
ANT2

10

Table 3. nRF402 pin functions

*) This pin is only for test purposes and is intended for use when measuring the loop filter voltage.

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PRODUCT SPECIFICATION

DD

DD

nRF402 Single Chip RF Transmitter

ELECTRICAL SPECIFICATIONS

Conditions: VDD = +3V DC, VSS = 0V, TA= -25°C to +85°C

Symbol Parameter (condition) Min. Typ. Max. Units

VDD Supply voltage 2.7 3 3.6 V

VSS Ground 0 V

I

Current consumption in transmit mode

DD

@ -10 dBm RF power 8 mA

I

P
V
V

f

XTAL

Current consumption in standby mode 8

DD

Max. RF output power @ 400Ω load

RF

Logic “1” input voltage

IH

Logic “0” input voltage 0

IL

I

Logic “1” input current (VI = VDD) +20

H

I

Logic “0” input current (VI = VSS) -20

L

f

Channel#1 frequency 433.92 MHz

1

f

Channel#2 frequency 434.33 MHz

2

Modulation type FSK
Frequency deviation

∆f

Crystal frequency
Bit rate 0 20 kbit/s

Z

Recommend antenna port differential load

I

impedance
Spurious emission Compliant with EN 300-220-1 V1.2.1

1)

0.7⋅V

10 dBm

0.3⋅V

±15

4.000 MHz

400

V

DD

µA

µA
µA

kHz

V
V

Ω

2)

Table 4. nRF402 electrical specifications

1) Crystal stability requirement must match the receiver requirement. For use with nRF401, the

crystal frequency stability should be better than ±45 ppm.

2) With PCB loop antenna or differential to single ended matching network to a 50Ω antenna.

ABSOLUTE MAXIMUM RATINGS

Supply voltages

VDD..............................- 0.3V to +6V

VSS ................................................0V

Input voltage

VI......................- 0.3V to VDD + 0.3V

Note: Stress exceeding one or more of the limiting values may cause permanent
damage to the device.

ATTENTION!

Electrostatic Sensitive Device
Observe Precaution for handling.

Total power dissipation

PD (TA=85°C)..........................230 mW

Temperatures

Operating Temperature -25°C to +85°C
Storage Temperature - 40°C to +125°C

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Revision: 2.1 Page 3 of 16 February 2000

PRODUCT SPECIFICATION

α

e b

nRF402 Single Chip RF Transmitter

PIN ASSIGNMENT

XC1
VSS

VCO1
VCO2
LPF
CS

1
2
3
4
5
6
7

nRF402

14 pin SSOIC

Figure 2. nRF402 pin assignment

PACKAGE OUTLINE

nRF402, 14 pin SSOIC. Dimensions in mm

14 13 12

14

13
12
11

10

9
8

XC2
PWR_UP
VSSVDD
ANT1
ANT2
DIN

RF_PWR

E H

1 2 3

D

A

1

A

L

Package Type D E H A A

14 pin SSOIC

(5.3 mm)

Min

Max

5.90

6.50

5.00

5.60

7.40

8.20 2.00

0.05

e b L Copl.

1

0.65

0.22

0.38

0.55

0.95 0.10

Figure 3. SSOIC-14 Package outline

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αα

0°
8°

PRODUCT SPECIFICATION

nRF402 Single Chip RF Transmitter

IMPORTANT TIMING DATA

Timing information

The timing information for the different operations is summarised in Table 5.
(TX is transmit mode, Std.by is standby mode.)

Change of Mode Name Max Delay Condition
Std.byè TX t

VDD=0 è TX t

ST

VT

Table 5 Switching times for nRF402

Switching between standby and TX-mode.

The maximum time from the PWR_UP input is set to “1”, until the synthesised
frequency is stable is tST, see Table 5 and Figure 4.

Std.by to TX

VDD

2ms Operational

mode

4ms Start-up

PWR_UP

DIN

2ms

ms

0 2 4

Figure 4 Timing diagram for nRF402 when going from standby to TX-mode

Powering up to transmit-mode (start-up).

Due to spurious emission when the power supply is switched on, the PWR_UP-input
must be kept low for 2ms after VDD > 2.7 V. Data (DIN) is valid within 2ms after
PWR_UP is high.

VDD=0 to TX

VDD

PWR_UP

DIN

2ms 2ms

ms

0

2 4

Figure 5. Timing diagram for nRF402, when powering up to TX-mode

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PRODUCT SPECIFICATION

RF out 50 ohm

nRF402 Single Chip RF Transmitter

APPLICATION INFORMATION

Antenna output

The ANT1 and ANT2 pins provide RF output from the output stage (PA) for nRF402.
The antenna connection to nRF402 is differential and the recommended load

impedance at the antenna port is 400Ω.

Figure 11 shows a typical application schematic with a differential loop antenna on a
Printed Circuit Board (PCB). The output stage (PA) consists of two open collector
transistors in a differential pair configuration. VDD to the PA must be supplied
through the collector load. When connecting a differential loop antenna to the
ANT1/ANT2 pins, VDD should be supplied through the centre of the loop antenna as
shown in Figure 11.

A single ended antenna or 50Ω test instrument may be connected to nRF402 by using
a differential to single ended matching network (BALUN) as shown in Figure 6.

VDD

180nH

22nH

ANT1

470pF

nRF402

ANT2

1.8pF

22nH

VDD

1nF

1.5pF

22nH

Figure 6. Connection of nRF402 to single ended antenna by using

a differential to single ended matching network

The 180nH inductor to VDD in Figure 6, need to have a Self-Resonance Frequency
(SRF) above 433 MHz to be effective. Suitable inductors are listed in Table 6.

Vendors WWW address Part. no., 180 nH inductors,

0603 size

Stetco http://www.stetco.com 0603G181KTE
Coilcraft http://www.coilcraft.com 0603CS-R18XJBC
muRata http://www.murata.com LQW1608AR18J00

Table 6. Vendors and part. no. for suitable 180nH inductors.

A single ended antenna may also be connected to nRF402 using an 8:1 impedance RF
transformer. The RF transformer must have a centre tap at the primary side for VDD
supply.

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PRODUCT SPECIFICATION

Total Chip Current

Current Consumption [mA]

RF Output Power

Power [dBm]

nRF402 Single Chip RF Transmitter

RF output power

The external bias resistor R3 connected between the RF_PWR pin and VSS sets the
output power. The RF output power may be set to levels up to +10dBm. In Figure 7
the output power is plotted for power levels down to, but not limited to, –8.5dBm for
a differential load of 400Ω. DC power supply current versus external bias resistor
value is shown in Figure 8.

10

8
6
4
2
0

-2

-4

-6

-8

-10
0 20 40 60 80 100 120 140 160 180 200

22

27

33

39

47

56

68

82

100

120

150

180

Resistor Value [kΩΩ]

Figure 7. RF Output power vs. external power setting resistor (R3) for nRF402

30,0

25,0

20,0

15,0

10,0

5,0

22

27

33

39

47

56

68

82

100

120

150

180

0,0

0 20 40 60 80 100 120 140 160 180 200

Resistor Value [kΩΩ]

Figure 8. Total chip current consumption vs. external power setting resistor (R3) for

nRF402

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PRODUCT SPECIFICATION

≤

≤

⋅

nRF402 Single Chip RF Transmitter

VCO inductor

An external 22nH inductor connected between the VCO1 and VCO2 pins is required
for the on-chip voltage controlled oscillator (VCO). This inductor should be a high
quality chip inductor, Q > 45 @ 433 MHz, with a maximum tolerance of ± 2%. The
following 22 nH inductors (0603) are suitable for use with nRF402, see Table 7.

Vendors WWW address Part. no., 22 nH inductors,

0603 size

Pulse http://www.pulseeng.com PE-0603CD220GTT
Coilcraft http://www.coilcraft.com 0603CS-22NXGBC
muRata http://www.murata.com LQW1608A22NG00
Stetco http://www.stetco.com 0603G220GTE
KOA http://www.koaspeer.com KQ0603TE22NG

Table 7. Vendors and part no. of suitable 22 nH inductors

See page 10 for PCB layout guidelines regarding placement of the inductor.

Crystal specification

To achieve an active crystal oscillator (XOSC) with low power consumption, certain
requirements apply for crystal loss and capacitive load.

The crystal specification is:

f= 4.0000 MHz Crystal parallel resonant frequency

pFCo 5

ohmESR 150

Crystal parallel equivalent capacitance

. Crystal equivalent series resistance

pFCL14≤ Total crystal load capacitance, including capacitance in

PCB layout.

For the crystal oscillator shown in Figure 9 the load capacitance becomes

C

= ,

L

´2´1CCCC

Where C1´ = C1 + C

´2´1

+

and C2´ = C2 + C

PCB1

PCB2

C1 and C2 are 0603 SMD capacitors as shown in the application schematic, see
Figure 11 and Table 8. C

PCB1

and C

are the layout parasitic capacitance on the

PCB2

circuit board.

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PRODUCT SPECIFICATION

nRF402 Single Chip RF Transmitter

Internal

External

components

Crystal

oscillator

Crystal

C1

R

C2

Crystal

equivalent

Co

Cs L

ESR

Figure 9. Crystal oscillator and crystal equivalent

Sharing a reference crystal with a micro-controller

Figure 10 shows circuit diagram of a typical application where nRF402 and a micro
controller share the reference crystal.

XC1

micro

controller

X1 X2

4.0 MHz

C1

22pF

R

C

5.6pF

C2

22pF

1.0M

nRF402

XC2

Figure 10. nRF402 and a micro-controller sharing the reference crystal

The crystal reference line from the micro-controller should not be routed close to full
swing digital data or control signals.

Channel#1 / Channel#2 selection

CS is a digital input for selection of either channel#1 (f1=433.92MHz)
or channel#2 (f2=434.33MHz).
CS = “0” selects channel#1.
CS = “1” selects channel#2.

DIN (data input)

The DIN pin is the input to the digital modulator of the transmitter. The input signal
to this pin should be standard CMOS logic level at data rates up to 20 kbit/s.

DIN = “1” → f = f0 + ∆f
DIN = “0” → f = f0 - ∆f

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PRODUCT SPECIFICATION

nRF402 Single Chip RF Transmitter

Power up

PWR_UP is a digital input for selection of normal operating mode or standby mode.
PWR_UP = “1” selects normal operating mode.
PWR_UP = “0” selects standby mode.

LPF pin

LPF is the loop filter test pin. This may be used for measurement of the loop filter
voltage. In a normal application this pin should only be connected to a solder pad. No
PCB lines should be connected to this pin.

Frequency difference between transmitter and receiver

Assuming the nRF401 transceiver chip is used for demodulation, the total frequency
difference between transmitter and receiver should not exceed 70 ppm (30 kHz). This
yields a crystal stability requirement of ±35 ppm for the transmitter and receiver.
Frequency difference exceeding this will result in a 12dB/octave drop in receiver
sensitivity. The functional window of the transmission link is typically 450 ppm (200
kHz).

Example: A crystal with ±20 ppm frequency tolerance and ±25 ppm frequency
stability over temperature has a worst case frequency difference of ±45 ppm. If the
transmitter and receiver operate in different temperature environments, the resulting
worst-case frequency difference may be as high as 90 ppm. Resulting drop in
sensitivity due to the extra 20 ppm, is then approx. 5dB.

PCB layout and decoupling guidelines

A well-designed PCB is necessary to achieve good RF performance. A PCB with a
minimum of two layers including a ground plane is recommended for optimum
performance.

The nRF402 DC supply voltage should be decoupled as close as possible to the VDD
pins with high performance RF capacitors, see Table 8. It is preferable to mount a
large surface mount capacitor (e.g. 2.2 µF ceramic) in parallel with the smaller value
capacitors. The nRF402 supply voltage should be filtered and routed separately from
the supply voltages of any digital circuitry.

Long power supply lines on the PCB should be avoided. All device grounds, VDD
connections and VDD bypass capacitors must be connected as close as possible to the
nRF402 IC. For a PCB with a topside RF ground plane, the VSS pins should be
connected directly to the ground plane. For a PCB with a bottom ground plane, the
best technique is to have via holes in or close to the VSS pads.

Full swing digital data or control signals should not be routed close to the external
VCO inductor or the LPF pin.

The VCO inductor placement is important. The optimum placement of the VCO
inductor gives a PLL loop filter voltage of 1.1 ±0.2 V, which can be measured at LPF
(pin 6). For a 22nH, 0603 size inductor the length between the centre of the

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PRODUCT SPECIFICATION

nRF402 Single Chip RF Transmitter

VCO1/VCO2 pad and the centre of the inductor pad should be 5.4 mm, see Figure 12
(c) (layout, top view), for a 2 layer, 1.6 mm thick FR4 PCB.

PCB layout example

Figure 12 shows a PCB layout example for the application schematic in Figure 11.
A double-sided FR-4 board of 1.6mm thickness is used. This PCB has a continuous
ground plane on the bottom layer. Additionally, there are ground areas on the
component side of the board to ensure sufficient grounding of critical components. A
large number of via holes connect the top layer ground areas to the bottom layer
ground plane. There is no ground plane beneath the antenna.

For more layout information, please refer to application note nAN400-06,
“nRF402 RF and antenna layout”.

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PRODUCT SPECIFICATION

nRF402 Single Chip RF Transmitter

APPLICATION SCHEMATIC

+3V

R1

C5

2.2uF
1206

C3

4.7nF
0603

C4
100pF
0603

L1
22nH
0603

1
2
3
4
5
6
7

CS

1M
0603

X1

C1

4.000 MHz

22pF
0603

REFERENCE

U1

XC1
VSS
VDD
VCO1
VCO2
LPF
CS

nRF402
433MHz Single chip RF Transmitter
SSOIC14

XC2

PWR_UP

VSS
ANT1
ANT2

DIN

RF_PWR

C2
22pF
0603

14
13

PWR_UP

12
11
10
9

DIN

8

R3
22K
0603

J1
Loop antenna
18x10mm
Q=55

C6
100pF
0603

C7

5.6pF
0603

C8
10pF
0603

R2
18K
0603

aaaaaaaa

Figure 11. nRF402 application Schematic

Component Description Size Value Tolerance Units

C1 NP0 ceramic chip capacitor, (Crystal oscillator) 0603 22 pF
C2 NP0 ceramic chip capacitor, (Crystal oscillator) 0603 22 pF
C3 X7R ceramic chip capacitor, (Supply decoupling) 0603 4.7 nF
C4 NP0 ceramic chip capacitor, (Supply decoupling) 0603 100 pF
C5 X7R ceramic chip capacitor, (Supply decoupling) 1206 2.2
C6 NP0 ceramic chip capacitor, (Supply decoupling) 0603 100 pF
C7 NP0 ceramic chip capacitor, (Antenna tuning) 0603 5.6
C8 NP0 ceramic chip capacitor, (Antenna tuning) 0603 10
L1 VCO inductor, Q>45 @ 433 MHz (See table 6.) 0603 22

±0.25
±0.25

±2%

R1 1/8W chip resistor, (Crystal oscillator) 0603 1.0
R2 1/8W chip resistor, (Antenna Q reduction) 0603 18
R3 1/8W chip resistor, (Transmitter power setting) 0603 22
X1 Crystal - 4.000 MHz

µF

pF
pF

nH

MΩ

kΩ
kΩ

Table 8 Recommended External Components

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PRODUCT SPECIFICATION

nRF402 Single Chip RF Transmitter

a) Top silk screen b) Bottom silk screen

c) Top view d) Bottom view

Figure 12. PCB layout (example) for nRF402 with loop antenna

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PRODUCT SPECIFICATION

nRF402 Single Chip RF Transmitter

DEFINITIONS

Data sheet status

Objective product specification This datasheet contains target specifications for product development.
Preliminary product
specification
Product specification This datasheet contains final product specifications. Nordic VLSI ASA

Limiting values

Stress above one or more of the limiting values may cause permanent damage to the device. These are stress
ratings only and operation of the device at these or at any other conditions above those given in the
Specifications sections of the specification is not implied. Exposure to limiting values for extended periods may
affect device reliability.

Application information

Where application information is given, it is advisory and does not form part of the specification.

Nordic VLSI ASA reserves the right to make changes without further notice to the
product to improve reliability, function or design. Nordic VLSI does not assume any
liability arising out of the application or use of any product or circuits described
herein.

This datasheet contains preliminary data; supplementary data may be
published from Nordic VLSI ASA later.

reserves the right to make changes at any time without notice in order to
improve design and supply the best possible product.

Table 9. Definitions

LIFE SUPPORT APPLICATIONS

These products are not designed for use in life support appliances, devices, or systems
where malfunction of these products can reasonably be expected to result in personal
injury. Nordic VLSI ASA customers using or selling these products for use in such
applications do so at their own risk and agree to fully indemnify Nordic VLSI ASA
for any damages resulting from such improper use or sale.

Product specification: Revision Date: 29.02.2000.

Datasheet order code: 290200nRF402.

All rights reserved ®. Reproduction in whole or in part is prohibited without the prior
written permission of the copyright holder.

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Revision: 2.1 Page 14 of 16 February 2000

PRODUCT SPECIFICATION

nRF402 Single Chip RF Transmitter

YOUR NOTES

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PRODUCT SPECIFICATION

nRF402 Single Chip RF Transmitter

Nordic VLSI - World Wide Distributors

For Your nearest dealer, please see http://www.nvlsi.no

Main Office:

Vestre Rosten 81, N-7075 Tiller, Norway

Phone: [phone], Fax: [phone]

E-mail: [e-mail]

Visit the Nordic VLSI ASA website at http://www.nvlsi.no

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