MAXIM MAX3100 Technical data

General Description

The MAX3100 universal asynchronous receiver transmitter (UART) is the first UART specifically optimized for small microcontroller-based systems. Using an SPI™/MICROWIRE™ interface for communication with the host microcontroller (µC), the MAX3100 comes in a compact 16-pin QSOP. The asynchronous I/O is suitable for use in RS-232, RS-485, IR, and opto-isolated data links. IR-link communication is easy with the MAX3100’s infrared data association (IrDA) timing mode.

The MAX3100 includes a crystal oscillator and a baudrate generator with software-programmable divider ratios for all common baud rates from 300 baud to 230k baud. A software- or hardware-invoked shutdown lowers quiescent current to 10µA, while allowing the MAX3100 to detect receiver activity.

An 8-word-deep first-in/first-out (FIFO) buffer minimizes processor overhead. This device also includes a flexible interrupt with four maskable sources, including address recognition on 9-bit networks. Two hardware-handshaking control lines are included (one input and one output).

The MAX3100 is available in 14-pin plastic DIP and small, 16-pin QSOP packages in the commercial and extended temperature ranges.

________________________Applications

Handheld Instruments

Intelligent Instrumentation

UART in SPI Systems

Small Networks in HVAC or Building Control

Isolated RS-232/RS-485: Directly Drives Opto-Couplers

Low-Cost IR Data Links for Computers/Peripherals

____________________________Features

♦ Small TQFN and QSOP Packages Available

♦ Full-Featured UART:

—IrDA SIR Timing Compatible —8-Word FIFO Minimizes Processor

Overhead at High Data Rates —Up to 230k Baud with a 3.6864MHz Crystal —9-Bit Address-Recognition Interrupt —Receive Activity Interrupt in Shutdown

♦ SPI/MICROWIRE-Compatible µC Interface

♦ Lowest Power:

—150µA Operating Current at 3.3V —10µA in Shutdown with Receive Interrupt

♦ +2.7V to +5.5V Supply Voltage in Operating Mode

♦ Schmitt-Trigger Inputs for Opto-Couplers ♦ TX and RTS Outputs Sink 25mA for Opto-Couplers

MAX3100

SPI/MICROWIRE-Compatible

UART in QSOP-16

________________________________________________________________

Maxim Integrated Products

Pin Configurations

19-1259; Rev 2; 1/09

PART

MAX3100CPD+

MAX3100CEE+ 0°C to +70°C

0°C to +70°C

TEMP RANGE PIN-PACKAGE

14 Plastic DIP

16 QSOP

Ordering Information

Typical Operating Circuit appears at end of data sheet.

SPI is a trademark of Motorola, Inc. MICROWIRE is a trademark of National Semiconductor Corp.

MAX3100EPD+

MAX3100EEE+ -40°C to +85°C

-40°C to +85°C 14 Plastic DIP

16 QSOP

MAX3100ETG+ -40°C to +85°C 24 TQFN-EP*

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

Denotes a lead(Pb)-free/RoHS-compliant package.

EP = Exposed pad.

TOP VIEW

DIN

DOUT

SCLK

IRQ

SHDN

GND

+ +

MAX3100

DIP

RTSCS

CTS

N.C.

DIN

N.C.

*EP = EXPOSED PAD, CONNECT EP TO GROUND

N.C.

18 17 16 15 14 13

123456

N.C.

CTS

RTS

MAX3100

DOUT

TQFN-EP

SCLK

N.C.

DIN

N.C.

GND

SHDN

*EP

IRQ

N.C.

DOUT

SCLK

N.C.

IRQ

SHDN

GND

MAX3100

QSOP

RTS

N.C.

CTS

MAX3100

SPI/MICROWIRE-Compatible UART in QSOP-16

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VCC= +2.7V to +5.5V, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are measured at 9600 baud at TA= +25°C.)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

VCCto GND ...........................................................................+6V

Input Voltage to GND

(CS, SHDN, X1, CTS, RX, DIN, SCLK) ....-0.3V to (V

+ 0.3V)

Output Voltage to GND

(DOUT, RTS, TX, X2) ..............................-0.3V to (V

+ 0.3V)

IRQ...........................................................................-0.3V to 6V

TX, RTS Output Current ....................................................100mA

X2, DOUT, IRQ Short-Circuit Duration

(to V

or GND) .........................................................Indefinite

Continuous Power Dissipation (T

= +70°C)

Plastic DIP (derate 10.00mW/°C above +70°C) .......... 800mW

QSOP (derate 8.30mW/°C above +70°C).....................667mW

TQFN (derate 33.3mW/°C above +70°C) ................2666.7mW

Operating Temperature Ranges

MAX3100C_ _ ......................................................0°C to +70°C

MAX3100E_ _ ...................................................-40°C to +85°C

Storage Temperature Range ............................ -65°C to +160°C

Lead Temperature (soldering, 10s) ................................ +300°C

SOURCE

= 25µA, TX only

IRQ

= 5.5V

SINK

= 4mA

DOUT only, CS = V

Shutdown mode

Active mode

SOURCE

= 5mA

VCC= 3.3V

VX1= 0V and 5.5V

CONDITIONS

VCC- 0.5

Output High Voltage

pF5C

OUT

Output Capacitance

µA±1I

Output Leakage

V0.4V

Output Low Voltage

pF5C

OUT

Output Capacitance

µA±1I

Output Leakage

DOUT, TX, RTS: I

SINK

= 4mA

TX, RTS: I

SINK

= 25mA

pF5C

Input Capacitance

V0.3 x V

Input Low Voltage

V0.7 x V

Input High Voltage

0.4

Output Low Voltage

0.9

VX1= 0V and 5.5V

/ 2 0.2 x V

Input Low Voltage

V0.7 x VCCV

/ 2V

Input High Voltage

V0.05 x V

HYST

Input Hysteresis

µA±1I

Input Leakage

pF5C

Input Capacitance

UNITSMIN TYP MAXSYMBOLPARAMETER

Input Current µA

VCC- 0.5

0.27 1

VCCSupply Current in Normal Mode

SHDN bit = 1 or SHDN = 0, logic inputs are at 0V or V

µA10I

VCCSupply Current in Shutdown

With 1.8432MHz crystal; all other logic inputs are at 0V or V

VCC= 5V

VCC= 3.3V 0.15 0.4

V2.7 5.5V

Supply Voltage

LOGIC INPUTS (DIN, SCLK, CS, SHDN, CTS, RX)

OSCILLATOR INPUT (X1)

OUTPUTS (DOUT, TX, RTS)

IRQ OUTPUT (Open Drain)

POWER REQUIREMENTS

MAX3100

SPI/MICROWIRE-Compatible

UART in QSOP-16

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VCC= +2.7V to +5.5V, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at TA= +25°C.)

LOAD

= 100pF

LOAD

= 100pF, RCS= 10kΩ

LOAD

= 100pF

CONDITIONS

ns100t

SCLK Low Time

ns100t

SCLK High Time

ns238t

SCLK Period

ns0t

DIN to SCLK Hold Time

ns100t

DIN to SCLK Setup Time

ns100t

SCLK Fall to DOUT Valid

ns0t

CSH

CS to SCLK Hold Time

ns100t

CSS

CS to SCLK Setup Time

ns100t

CS High to DOUT Tri-State

ns100t

CS Low to DOUT Valid

UNITSMIN TYP MAXSYMBOLPARAMETER

TX, RTS, DOUT: C

LOAD

= 100pF

(Note 1)

ns10t

Output Rise Time

ns200t

CSW

CS High Pulse Width

ns100t

CS0

SCLK Rising Edge to CS Falling

(Note 1) ns200t

CS1

CS Rising Edge to SCLK Rising

Figure 1. Detailed Serial-Interface Timing

TX, RTS, DOUT, IRQ: C

LOAD

= 100pF

ns10t

Output Fall Time

AC TIMING (Figure 1)

Note 1: t

CS0

and t

CS1

specify the minimum separation between SCLK rising edges used to write to other devices on the SPI bus

and the CS used to select the MAX3100. A separation greater than t

CS0

and t

CS1

ensures that the SCLK edge is ignored.

CSS

SCLK

DIN

DOUT

CSH

• • •

CSH

MAX3100

SPI/MICROWIRE-Compatible UART in QSOP-16

4 _______________________________________________________________________________________

__________________________________________Typical Operating Characteristics

(TA = +25°C, unless otherwise noted.)

SUPPLY CURRENT vs. TEMPERATURE

1000

900

800

700

600

500

400

300

SUPPLY CURRENT (μA)

200

100

-40 -20 40 60 100

020 80

TEMPERATURE (°C)

SUPPLY CURRENT vs. BAUD RATE

400

1.8432 MHz CRYSTAL

350

300

250

200

SUPPLY CURRENT (μA)

150

100

3V TRANSMITTING

1000

100 10k

1.8432MHz CRYSTAL TRANSMITTING AT

115.2 kbps

VCC = 5V

VCC = 3.3V

5V TRANSMITTING

BAUD RATE (bps)

5V STANDBY

3V STANDBY

100k 1M

MAX3100-01

SHUTDOWN CURRENT (μA)

-40 -20 40 60 100

TX, RTS, DOUT OUTPUT CURRENT

vs. OUTPUT LOW VOLTAGE (V

MAX3100-03a

OUTPUT SINK CURRENT (mA)

0 0.20.1 0.6 0.7

SHUTDOWN CURRENT

vs. TEMPERATURE

1.8432MHz CRYSTAL

VCC = 5V

020 80

TEMPERATURE (°C)

RTS

DOUT

0.3 0.50.4 0.9 VOLTAGE (V)

0.8

= 3.3V)

700

MAX3100-02

600

500

400

300

SUPPLY CURRENT (μA)

200

100

MAX3100-04

OUTPUT SINK CURRENT (mA)

1.0

SUPPLY CURRENT vs.

EXTERNAL CLOCK FREQUENCY

= 5V

= 3.3V

01 3

EXTERNAL CLOCK FREQUENCY (MHz)

TX, RTS, DOUT OUTPUT CURRENT

vs. OUTPUT LOW VOLTAGE (V

RTS

DOUT

0 0.20.1 0.6 0.7

0.3 0.50.4 0.9 VOLTAGE (V)

0.8

MAX3100-03

= 5V)

MAX3100-05

1.0

MAX3100

SPI/MICROWIRE-Compatible

UART in QSOP-16

_______________________________________________________________________________________ 5

Detailed Description

The MAX3100 universal asynchronous receiver transmitter (UART) interfaces the SPI/MICROWIRE-compatible, synchronous serial data from a microprocessor (µP) to asynchronous, serial-data communication ports (RS-232, RS-485, IrDA). Figure 2 shows the MAX3100 functional diagram.

The MAX3100 combines a simple UART and a baudrate generator with an SPI interface and an interrupt generator. Configure the UART by writing a 16-bit word to a write-configuration register, which contains the baud rate, data-word length, parity enable, and enable of the 8-word receive first-in/first-out (FIFO). The write configuration selects between normal UART timing and IrDA timing, controls shutdown, and contains 4 interrupt mask bits.

Transmit data by writing a 16-bit word to a write-data register, where the last 7 or 8 bits are actual data to be transmitted. Also included is the state of the transmitted parity bit (if enabled). This register controls the state of the RTS output pin. Received words generate an inter- rupt if the receive-bit interrupt is enabled.

Read data from a 16-bit register that holds the oldest data from the receive FIFO, the received parity data, and the logic level at the CTS input pin. This register also contains a bit that is the framing error in normal operation and a receive-activity indicator in shutdown.

The baud-rate generator determines the rate at which the transmitter and receiver operate. Bits B0 to B3 in the write-configuration register determine the baud-rate divisor (BRD), which divides down the X1 oscillator frequency. The baud clock is 16 times the data rate (baud rate).

Pin Description

QSOP DIP

NAME FUNCTION

1 1 23 DIN SPI/MICROWIRE Serial-Data Input. Schmitt-trigger input. 2 2 2 DOUT SPI/MICROWIRE Serial-Data Output. High impedance when CS is high.

3 3 3 SCLK SPI/MICROWIRE Serial-Clock Input. Schmitt-trigger input.

444CS

Active-Low Chip-Select Input. DOUT goes high impedance when CS is high, IRQ, TX, and RTS are always active. Schmitt-trigger input.

655IRQ Active-Low Interrupt Output. Open-drain interrupt output to microprocessor.

768SHDN

Hardware-Shutdown Input. When shut down (SHDN = 0), the oscillator turns off immediately without waiting for the current transmission to end, reducing supply current to just leakage currents.

8 7 9 GND Ground

9 8 10 X2

Crystal Connection. Leave X2 unconnected for external clock. See Crystal- Oscillator Operation—X1, X2 Connection section.

10 9 11 X1

Crystal Connection. X1 also serves as an external clock input. See Crystal- Oscillator Operation—X1, X2 Connection section.

11 10 15 CTS

General-Purpose Active-Low Input. Read via the CTS register bit; often used for RS-232 clear-to-send input (Table 1).

13 11 16 RTS

General-Purpose Active-Low Output. Controlled by the CTS register bit. Often used for RS-232 request-to-send output or RS-485 driver enable.

14 12 17 RX

Asynchronous Serial-Data (receiver) Input. The serial information received from the modem or RS-232/RS-485 receiver. A transition on RX while in shutdown generates an interrupt (Table 5).

15 13 21 TX Asynchronous Serial-Data (transmitter) Output

16 14 22 V

Positive Supply Pin (2.7V to 5.5V)

5, 12 —

1, 6, 7, 12, 13, 14, 18,

N.C. No Connection. Not internally connected.

— — — EP Exposed Pad. Connect EP to ground or leave unconnected.

TQFN-EP

19, 20, 24

MAX3100

SPI/MICROWIRE-Compatible UART in QSOP-16

6 _______________________________________________________________________________________

Figure 2. Functional Diagram

The transmitter section accepts SPI/MICROWIRE data, formats it, and transmits it in asynchronous serial format from the TX output. Data is loaded into the transmit-

buffer register from the SPI/MICROWIRE interface. The MAX3100 adds start and stop bits to the data and clocks the data out at the selected baud rate (Table 7).

Pt TX-BUFFER REGISTER

(SOURCES)

PrRT

IRQ

INTERRUPT

LOGIC

RA/FE

DIN

SCLK

DOUT

(MASKS) TRANSMIT-DONE (TM)

DATA-RECEIVED (RM)

PARITY (PM)

FRAMING ERROR (RAM)/ RECEIVE ACTIVITY

SPI

INTERFACE

SHDN

TX-SHIFT REGISTER

B0 B1 B2 B3

RX-SHIFT REGISTER

PrPrRX-BUFFER REGISTER

D0t–D7t

BAUD-RATE

BAUD-RATE GENERATOR

GENERATOR

D0r–D7r

RX-BUFFER REGISTER

XTAL

START/STOP-

ACTIVITY

DETECT

BIT DETECT

I / O

CTS

RTS

MAX3100

The receiver section receives data in serial form. The MAX3100 detects a start bit on a high-to-low RX transition (Figure 3). An internal clock samples data at 16 times the data rate. The start bit can occur as much as one clock cycle before it is detected, as indicated by the shaded portion. The state of the start bit is defined as the majority of the 7th, 8th, and 9th sample of the internal 16x baud clock. Subsequent bits are also majority sampled. Receive data is stored in an 8-word FIFO. The FIFO is cleared if it overflows.

The on-board oscillator can use a 1.8432MHz or

3.6864MHz crystal, or it can be driven at X1 with a 45% to 55% duty-cycle square wave.

SPI Interface

The bit streams for DIN and DOUT consist of 16 bits, with bits assigned as shown in the

MAX3100

Operations

section. DOUT transitions on SCLK’s falling

edge, and DIN is latched on SCLK’s rising edge (Figure

4). Most operations, such as the clearing of internal registers, are executed only on CS’s rising edge. The DIN stream is monitored for its first two bits to tell the UART the type of data transfer being executed (Write Config, Read Config, Write Data, Read Data).

Only 16-bit words are expected. If CS goes high in the middle of a transmission (any time before the 16th bit), the sequence is aborted (i.e., data does not get written to individual registers). Every time CS goes low, a new 16-bit stream is expected. An example of a write configuration is shown in Figure 4.

SPI/MICROWIRE-Compatible

UART in QSOP-16

_______________________________________________________________________________________ 7

Figure 3. Start-Bit Timing

Figure 4. SPI Interface (Write Configuration)

ONE BAUD PERIOD

BAUD

BLOCK

SCLK

DIN

DOUT

11 FEN SHDN TM RM PM RAM IR ST PE L B3 B2 B1 B0

RT 00 000 00 00 00 000

23456 789

2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

10 11

MAJORITY

CENTER

SAMPLER

12 13 14 15 16

DATA

UPDATED

MAX3100

SPI/MICROWIRE-Compatible UART in QSOP-16

8 _______________________________________________________________________________________

MAX3100 Operations

Write Operations

Table 1 shows write-configuration data. A 16-bit SPI/MICROWIRE write configuration clears the receive FIFO and the R, T, RA/FE, D0r–D7r, D0t–D7t, Pr, and Pt registers. RTS and CTS remain unchanged. The new configuration is valid on CS’s rising edge if the transmit buffer is empty (T = 1) and transmission is over. If the latest transmission has not been completed, the registers are updated when the transmission is over (T = 0).

The write-configuration bits (FEN, SHDNi, IR, ST, PE, L, B3–B0) take effect after the current transmission is over. The mask bits (TM, RM, PM, RAM) take effect immediately after the 16th clock’s rising edge at SCLK.

Read Operations

Table 2 shows read-configuration data. This register reads back the last configuration written to the

MAX3100. The device enters test mode if bit 0 = 1. In this mode, if CS = 0, the RTS pin acts as the 16x clock generator’s output. This may be useful for direct baudrate generation (in this mode, TX and RX are in digital loopback).

Normally, the write-data register loads the TX-buffer register. To change the RTS pin’s state without writing data, set the TE bit. Setting the TE bit high inhibits the write command (Table 3).

Reading data clears the R bit and interrupt IRQ (Table 4).

Table 5 shows read/write operation and power-on reset state (POR), and describes each bit used in programming the MAX3100. Figure 5 shows parity and wordlength control.

D6t

D6r

D7t

D7r

15 2

DIN 1 D2t

DOUT R D2r

BIT 3

D3t

D3r

D0t

D0r

D1t

D1r

D4t

D4r

D5t

D5r

RA/FE

RTS

CTS

D6r

D7r

15 2

DIN 0 0

DOUT R D2r

BIT 3

D3r

D0r

D1r

D4r

D5r

RA/FE

CTS

Table 3. Write Data (D15, D14 = 1, 0)

Table 4. Read Data (D15, D14 = 0, 0)

15 2

DIN 0 0

DOUT R B2

BIT 3

TEST

RAM

SHDNo

FEN

Table 2. Read Configuration (D15, D14 = 0, 1)

RAM

SHDNi

FEN

15 14

DIN 1

DOUT R

BIT

Table 1. Write Configuration (D15, D14 = 1, 1)

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