Maxim MAX3111ECNI, MAX3110EEWI, MAX3110EENI, MAX3110ECWI, MAX3110ECNI Datasheet

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General Description

The MAX3110E/MAX3111E combine a full-featured uni­versal asynchronous receiver/transmitter (UART) with
±15kV ESD-protected RS-232 transceivers and inte­grated charge-pump capacitors into a single 28-pin
package for use in space-, cost-, and power-con­strained applications. The MAX3110E/MAX3111E also
feature an SPI™/QSPI™/MICROWIRE™-compatible
serial interface to save additional board space and
microcontroller (µC) I/O pins.

A proprietary low-dropout output stage enables the
2-driver/2-receiver interface to deliver true RS-232 per­formance down to VCC= +3V (+4.5V for MAX3110E)
while consuming only 600µA. The receivers remain
active in a hardware/software-invoked shutdown, allow­ing external devices to be monitored while consuming
only 10µA. Each device is guaranteed to operate at up
to 230kbps while maintaining true EIA/TIA-232 output
voltage levels.

The MAX3110E/MAX3111E’s UART includes a crystal
oscillator and baud-rate generator with software-pro­grammable divider ratios for all common baud rates
from 300baud to 230kbaud. The UART features an 8­word-deep receive FIFO that minimizes processor over­head and provides a flexible interrupt with four
maskable sources. Two control lines (one input and
one output) are included for hardware handshaking.

The UART and RS-232 functions can be used together
or independently since the two functions share only
supply and ground connections (the MAX3110E/
MAX3111E are hardware- and software-compatible
with the MAX3100 and MAX3222E).

________________________Applications

Point-of-Sale (POS) Devices
Handy-Terminals
Telecom/Networking Diagnostic Ports
Industrial Front-Panel Interfaces
Hand-Held/Battery-Powered Equipment

Features

♦ Integrated RS-232 Transceiver and UART in a

Single 28-Pin Package

♦ SPI/QSPI/MICROWIRE-Compatible µC Interface
♦ Internal Charge-Pump Capacitors—

No External Components Required!

♦ True RS-232 Operation Down to V

CC

= +3V

(MAX3111E)

♦ ESD Protection for RS-232 I/O Pins

±15kV—Human Body Model
±8kV—IEC 1000-4-2, Contact Discharge
±15kV—IEC 1000-4-2, Air-Gap Discharge

♦ Single-Supply Operation

+5V (MAX3110E)
+3.3V (MAX3111E)

♦ Low Power

600µA Supply Current
10µA Shutdown Supply Current with

Receiver Interrupt Active

♦ Guaranteed 230kbps Data Rate
♦ Hardware/Software-Compatible with MAX3100

and MAX3222E

MAX3110E/MAX3111E

†

SPI/MICROWIRE-Compatible UART and ±15kV ESD-

Protected RS-232 Transceivers with Internal Capacitors

________________________________________________________________

Maxim Integrated Products

1

678

RS-232

DB-9

CS
SCLK

SPI

DIN

DOUT

µP

U
A
R
T

9

12345

IRQ

MAX3110E
MAX3111E

19-1494; Rev 0; 7/99

Typical Application Circuit

Ordering Information

SPI and QSPI are trademarks of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corp.

Ordering Information continued at end of data sheet.

Pin Configuration appears at end of data sheet.

†

Covered by U.S. Patent numbers 4,636,930; 4,679,134;
4,777,577; 4,797,899; 4,809,152; 4,897,774; 4,999,761; and
other patents pending.

PART

MAX3110ECWI

MAX3110ECNI 0°C to +70°C

0°C to +70°C

TEMP.

RANGE

PIN-

PACKAGE

28 Wide SO
28 Plastic DIP

V

CC

(V)

5
5

MAX3110E/MAX3111E

SPI/MICROWIRE-Compatible UART and ±15kV ESD­Protected RS-232 Transceivers with Internal Capacitors

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS—MAX3110E

(VCC= +4.5V to +5.5V, TA = T

MIN

to T

MAX

, unless otherwise noted. Typical values are measured for baud rate set to 9600baud at

VCC= +5V, TA= +25°C.) (Note 2)

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 (MAX3110E) ........................................-0.3V to +6V

VCCto GND (MAX3111E).........................................-0.3V to +4V

V+ to GND (Note 1)..................................................-0.3V to +7V

V- to GND (Note 1) ...................................................+0.3V to -7V

V+ to V- (Note 1)..................................................................+13V

Input Voltages to GND

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

CC

+ 0.3V)

T_IN, SHDN ...........................................................-0.3V to +6V

R_IN ..................................................................................±25V

Output Voltage to GND

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

CC

+ 0.3V)

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

T_OUT ...........................................................................±13.2V

R_OUT.....................................................-0.3V to (V

CC

+ 0.3V)

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

Short-Circuit Duration

X2, DOUT, IRQ (to V

CC

or GND).............................Continuous

T_OUT (to GND) .....................................................Continuous

Continuous Power Dissipation (T

A

= +70°C)

28-pin Wide SO (derate 12.5mW/°C above +70°C) ...........1W

28-pin Plastic DIP (derate 14.3mW/°C above +70°C) ....1.14W

Operating Temperature Ranges

MAX311_EC_ _ .................................................. 0°C to +70°C

MAX311_EE_ _ ................................................-40°C to +85°C

Storage Temperature Range ............................-65°C to +150°C

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

Note 1: V+ and V- can have maximum magnitudes of 7V, but their absolute difference should not exceed 13V.

SHDNi bit = 1

SHDNi bit = 0

2

Input Current I

IN1

25

µAVX1= 0 or 5.5V

PARAMETER SYMBOL MIN TYP MAX UNITS

Input Low Voltage V

IL1

0.2V

CC

V

Input High Voltage V

IH1

0.7V

CC

V

V

Supply Current with Hardware
and Software Shutdown

I

CCSHDN(H+ S)

320µA

Input Capacitance C

IN1

5 pF

Input High Voltage V

IH2

0.7V

CC

V

Input Low Voltage V

IL2

0.3V

CC

V

Supply Current I

CC

0.6 2 mA

Supply Current with Hardware
Shutdown

I

CCSHDN(H)

0.48 1 mA

Input Hysteresis V

HYST2

250 mV

Input Leakage Current I

LKG1

±1 µA

Input Capacitance C

IN2

5 pF

Input High Voltage V

IH3

2.4

Input Low Voltage V

IL3

0.8 V

Transmitter Input Hysteresis V

HYST3

500 mV

Input Leakage Current I

IN3

±0.01 ±1 µA

CONDITIONS

SHDN = GND, SHDNi bit = 1 (Note 4)

VCC= 5V

SHDN = VCC, no load

SHDN = GND (Note 3)

DC CHARACTERISTICS (VCC= +5V, TA= +25°C)

UART OSCILLATOR INPUT (X1)

UART LOGIC INPUTS (DIN, SCLK, CS, CTS, RX

))

RS-232 LOGIC INPUTS (T_IN, SHDN

))

±25

MAX3110E/MAX3111E

SPI/MICROWIRE-Compatible UART and ±15kV ESD-

Protected RS-232 Transceivers with Internal Capacitors

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS—MAX3110E (continued)

(VCC= +4.5V to +5.5V, TA = T

MIN

to T

MAX

, unless otherwise noted. Typical values are measured for baud rate set to 9600baud at

VCC= +5V, TA= +25°C.) (Note 2)

CONDITIONS UNITSMIN TYP MAXSYMBOLPARAMETER

mV500V

HYST4

Input Hysteresis

V0.8V

IL4

Input Low Voltage

V2.4V

IH4

Input High Voltage

TA= +25°C kΩ357R

IN

Input Resistance

TA= +25°C, VCC= 5V
TA= +25°C, VCC= 5V

V-25 +25Input Voltage Range

0.9I

SINK

= 25mA; TX only

Output Low Voltage V

OL2

0.4
V

I

SINK

= 4mA; DOUT, RTS

V

CC

- 0.5I

SOURCE

= 10mA; TX only

±8

kV

IEC 1000-4-2 Contact Discharge

±15IEC 1000-4-2 Air Discharge

SCLK Fall to DOUT Valid t

DO

100 nsC

LOAD

= 100pF

CS to SCLK Hold Time

t

CSH

0 ns

Output Low Voltage V

OL1

0.4 V

Output High Voltage V

OH1

VCC- 0.6 V±0.05 ±10 µA

Output Voltage Swing 5 ±5.4 V
Output Resistance R

O

300 10M Ω

Output Short-Circuit Current ±60 mA

Output Leakage Current I

LKG2

±25 µA

ESD Protection

±15

Output Leakage Current I

LKG3

±1 µA

Output High Voltage V

OH2

V

CC

- 0.5
V

Output Capacitance C

OUT1

5 pF

Output Leakage Current I

LKG4

±1 µA

Output Low Voltage V

OL3

0.4 V

Output Capacitance C

OUT2

5 pF

CS Low to DOUT Valid

t

DV

100 ns

CS High to DOUT Tri-State

t

TR

100 ns

CS to SCLK Setup Time

t

CSS

100 ns

DOUT only, CS = V

CC

I

SINK

= 1.6mA

I

SOURCE

= 1mAReceivers disabled

3kΩ load on all transmitter outputs
V

CC

= V+ = V- = 0, V

OUT

= ±2V

I

SOURCE

= 5mA; DOUT, RTS

VCC= 0 or 5.5V, V

OUT

= ±12V,

transmitters disabled

V

IRQ

= 5.5V

I

SINK

= 4mA

Human Body Model

C

LOAD

= 100pF

C

LOAD

= 100pF, RCS= 10kΩ

RS-232 RECEIVER INPUTS (R_IN)

RS-232 ESD PROTECTION (R_IN, T_OUT)

RS-232 RECEIVER OUTPUTS (R_OUT)

RS-232 TRANSMITTER OUTPUTS (T_OUT)

UART OUTPUTS (DOUT, TX, RTS)

UART IRQ OUTPUTS (IRQ = open drain)

UART AC TIMING

MAX3110E/MAX3111E

SPI/MICROWIRE-Compatible UART and ±15kV ESD­Protected RS-232 Transceivers with Internal Capacitors

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS—MAX3110E (continued)

(VCC= +4.5V to +5.5V, TA = T

MIN

to T

MAX

, unless otherwise noted. Typical values are measured for baud rate set to 9600baud at

VCC= +5V, TA= +25°C.) (Note 2)

CONDITIONS UNITSMIN TYP MAXSYMBOLPARAMETER

ns0t

DH

DIN to SCLK Hold Time

ns100t

DS

DIN to SCLK Setup Time

ns238t

CP

SCLK Period

ns100t

CL

SCLK Low Time

ns100t

CH

SCLK High Time

ns100t

CS0

SCLK Rising Edge to CS Falling

TX, RTS, DOUT; CL= 100pF

ns10t

r

Output Rise Time

ns200t

CSW

CS High Pulse Width

ns200t

CS1

CS Rising Edge to SCLK Rising
Edge

TX, RTS, DOUT, IRQ; CL= 100pF

ns10t

f

Output Fall Time

CL= 150pF to
2500pF

430

V/µs

Receiver Skew |t

PHL

- t

PLH

| 50 ns

CL= 150pF to
1000pF

Transmitter Skew |t

PHL

- t

PLH

| 100 ns

t

PLH

150

ns

Transition-Region Slew Rate

630

Maximum Data Rate 250 kbps

Receiver Propagation Delay

t

PHL

150

(Note 5)

CL= 150pF

VCC= 5V,
RL= 3kΩ to 7kΩ,
TA= +25°C,
measured from
+3V to -3V or

-3V to +3V

RL= 3kΩ, CL= 1000pF,
one transmitter switching

Receiver input to receiver output

RS-232 AC TIMING

kV

Human Body Model

SPI/MICROWIRE-Compatible UART and ±15kV ESD-

Protected RS-232 Transceivers with Internal Capacitors

_______________________________________________________________________________________ 5

MAX3110E/MAX3111E

SHDN = GND (Note 3)

SHDN = VCC, no load

SHDN = GND SHDNi bit = 1 (Note 4)

CONDITIONS

pF

5

C

IN2

Input Capacitance

µA±1I

LKG1

Input Leakage Current

mV165V

HYST2

Input Hysteresis

mA0.18 0.4I

CCSHDN(H)

Supply Current with Hardware
Shutdown

mA0.45 1.4I

CC

Supply Current

V0.3V

CC

V

IL2

Input Low Voltage

V0.7V

CC

V

IH2

Input High Voltage

pF5C

IN1

µA120I

CCSHDN(H+ S)

Supply Current with Hardware
and Software Shutdown

V
V0.7V

CC

V

IH1

Input High Voltage

V0.2V

CC

V

IL1

Input Low Voltage

UNITSMIN TYP MAXSYMBOLPARAMETER

VX1= 0 or 3.6V µA

25

I

IN1

Input Current

2

SHDNi bit = 0
SHDNi bit = 1

ELECTRICAL CHARACTERISTICS—MAX3111E

(VCC= +3.0V to +3.6V, VA = T

MIN

to T

MAX

, unless otherwise noted. Typical values are measured for baud rate set to 9600baud at

VCC= +3.3V, TA= +25°C.) (Note 2)

TA= +25°C, VCC= 3.3V

VCC= 3.3V

mV500V

HYST4

Input Hysteresis

V0.6V

IL4

Input Low Voltage

V2.4V

IH4

Input High Voltage

µA±0.01 ±1I

IN3

Input Leakage Current

mV500V

HYST3

Transmitter Input Hysteresis

V0.8V

IL3

Input Low Voltage

V2.0V

IH3

Input High Voltage

TA= +25°C kΩ357R

IN

Input Resistance

TA= +25°C, VCC= 3.3V

V-25 +25Input Voltage Range

±15

ESD Protection

IEC 1000-4-2 Air Discharge ±15
IEC 1000-4-2 Contact Discharge ±8

Input Capacitance

DC CHARACTERISTICS (VCC= 3.3V, TA= +25°C)

UART OSCILLATOR INPUT (X1)

UART LOGIC INPUTS (DIN, SCLK, CS, RX

))

RS-232 LOGIC INPUTS (T_IN, SHDN)

RS-232 RECEIVER INPUTS (R_IN)

RS-232 ESD PROTECTION (R_IN, T_OUT)

MAX3110E/MAX3111E

SPI/MICROWIRE-Compatible UART and ±15kV ESD­Protected RS-232 Transceivers with Internal Capacitors

6 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS—MAX3111E (continued)

(VCC= +3.0V to +3.6V, VA = T

MIN

to T

MAX

, unless otherwise noted. Typical values are measured for baud rate set to 9600baud at

VCC= +3.3V, TA= +25°C.) (Note 2)

Output Fall Time t

f

10 ns

TX, RTS, DOUT, IRQ; C

LOAD

= 100pF

CS Rising Edge to SCLK Rising
Edge

t

CS1

200 ns

CS High Pulse Width

t

CSW

200 ns

Output Rise Time t

r

10 ns

TX, RTS, DOUT; C

LOAD

= 100pF

SCLK Rising Edge to CS Falling

t

CS0

100 ns

SCLK High Time t

CH

100 ns

SCLK Low Time t

CL

100 ns

SCLK Period t

CP

238 ns

SCLK Fall to DOUT Valid t

DO

100 ns

DIN to SCLK Setup Time t

DS

100 ns

DIN to SCLK Hold Time t

DH

0 ns

C

LOAD

= 100pF

CS to SCLK Hold Time

t

CSH

0 ns

CS Low to DOUT Valid

t

DV

100 ns

CS High to DOUT Tri-State

t

TR

100 ns

CS to SCLK Setup Time

t

CSS

100 ns

C

LOAD

= 100pF

C

LOAD

= 100pF, RCS= 10kΩ

0.9I

SINK

= 25mA, TX only

Output Low Voltage V

OL2

0.4
V

±25

V

CC

- 0.5

I

SINK

= 4mA; DOUT, RTS

Output Low Voltage V

OL1

0.4 V

Output High Voltage V

OH1

VCC- 0.6 V

Output Voltage Swing ±5 ±5.4 V
Output Resistance R

O

300 10M Ω

Output Short-Circuit Current ±60 mA

Output Leakage Current I

LKG2

µA

I

SOURCE

= 10mA, TX only

PARAMETER SYMBOL MIN TYP MAX UNITS

Output Leakage Current I

LKG3

±1 µA

Output High Voltage V

OH2

V

CC

- 0.5
V

Output Capacitance C

OUT1

5 pF

Output Leakage Current I

LKG4

±1 µA

Output Low Voltage V

OL3

0.4 V

Output Capacitance C

OUT2

5 pF

DOUT only; CS = V

CC

I

SINK

= 1.6mA

I

SOURCE

= 1mA

3kΩ load on all transmitter outputs

V

CC

= V+ = V- = 0, V

OUT

= ±2V

I

SOURCE

= 5mA; DOUT, RTS

VCC= 0 or 3.6V, V

OUT

= ±12V,

transmitters disabled

V

IRQ

= 3.6V

I

SINK

= 4mA

CONDITION

RS-232 RECEIVER OUTPUTS (R_OUT)

RS-232 TRANSMITTER OUTPUTS (T_OUT)

UART OUTPUTS (DOUT, TX, RTS)

UART IRQ OUTPUT (IRQ = open drain)

UART AC TIMING

ns

MAX3110E/MAX3111E

SPI/MICROWIRE-Compatible UART and ±15kV ESD-

Protected RS-232 Transceivers with Internal Capacitors

_______________________________________________________________________________________ 7

ELECTRICAL CHARACTERISTICS—MAX3111E (continued)

(VCC= +3.0V to +3.6V, VA = T

MIN

to T

MAX

, unless otherwise noted. Typical values are measured for baud rate set to 9600baud at

VCC= +3.3V, TA= +25°C.) (Note 2)

Note 2: All currents into the device are positive; all currents out of the device are negative. All voltages are referred to device

ground unless otherwise noted.

Note 3: I

CCSHDN(H)

represents a hardware-only shutdown. In hardware shutdown, the UART is in normal operation and the charge

pumps for the RS-232 transmitters are shut down.

Note 4: I

CCSHDN(H+S)

represents a simultaneous software and hardware shutdown in which the UART and charge pumps are

shut down.

Note 5: Transmitter skew is measured at the transmitter zero cross points.

Receiver input to receiver output

RL= 3kΩ, CL= 1000pF,
one-transmitter switching

VCC= 3.3V,
RL= 3kΩ to 7kΩ,
TA= +25°C,
measured from
+3V to -3V or

-3V to +3V

CL= 150pF
(Note 5)

150t

PHL

Receiver Propagation Delay

kbps250Maximum Data Rate

V/µs

630

Transition-Region Slew Rate

ns

150t

PLH

CL= 150pF to
1000pF

ns200|t

PHL

- t

PLH

| Transmitter Skew

ns100|t

PHL

- t

PLH

| Receiver Skew

430

CL= 150pF to
2500pF

CONDITIONS UNITSMIN TYP MAXSYMBOLPARAMETER

RS-232 AC TIMING

MAX3110E/MAX3111E

SPI/MICROWIRE-Compatible UART and ±15kV ESD­Protected RS-232 Transceivers with Internal Capacitors

8 _______________________________________________________________________________________

0

10

5

15

30

35

40

25

20

50

0 1000 2000

250kbps

3000 4000 5000

RS-232 TRANSCEIVER SUPPLY CURRENT

vs. LOAD CAPACITANCE

MAX3110E/TOC09

LOAD CAPACITANCE (pF)

SUPPLY CURRENT (mA)

45

TRANSMITTER 1 AT DATA RATE
TRANSMITTER 2 AT DATA RATE
3kΩ + C

L

16

120kbps

20kbps

0

4

2

6

12

14

10

8

16

0 1000 2000 3000 4000 5000

RS-232 TRANSMITTER SLEW RATE

vs. LOAD CAPACITANCE

MAX3110E/TOC11

LOAD CAPACITANCE (pF)

SLEW RATE (V/µs)

TRANSMITTER 1 AT 250kbps
3kΩ + C

L

-SLEW

+SLEW

-10.0

-5.0

-7.5

-2.5

5.0

7.5

2.5

0

10.0

0 1000 2000 3000 4000 5000

RS-232 TRANSMITTER OUTPUT VOLTAGE

vs. LOAD CAPACITANCE

MAX3110E/TOC07

LOAD CAPACITANCE (pF)

TRANSMITTER OUTPUT VOLTAGE (V)

TRANSMITTER 1 AT 250kbps
TRANSMITTER 2 AT 15.6kbps
3kΩ + C

L

V

OUT-

V

OUT+

Typical Operating Characteristics

(TA = +25°C, unless otherwise noted.)

1000

900

0

-40 -20 40 60 100

UART SUPPLY CURRENT vs. TEMPERATURE

200

100

800

700

MAX3110E-01

TEMPERATURE (°C)

SUPPLY CURRENT (µA)

020 80

600

500

400

300

MAX3110E, VCC = +5V

MAX3111E, VCC = +3.3V

1.8432MHz CRYSTAL
TRANSMITTING AT 115.2kbps

10

9

0

-40 -20 40 60 100

UART SHUTDOWN CURRENT

vs. TEMPERATURE

2

1

8

7

MAX3110E-02

TEMPERATURE (°C)

SHUTDOWN CURRENT (µA)

020 80

6

5

4

3

1.8432MHz CRYSTAL

MAX3110E, VCC = +5V

MAX3111E, VCC = +3.3V

400

50

100 10k

1000

100k 1M

UART SUPPLY CURRENT

vs. BAUD RATE

150

100

MAX3110E-03

BAUD RATE (bps)

SUPPLY CURRENT (µA)

200

250

350

300

1.8432MHz
CRYSTAL

MAX3110E

MAX3111E

+5V
STANDBY

+5V
TRANSMITTING

+3V
TRANSMITTING

+3V
STANDBY

700

600

0

01 3

4

5

UART SUPPLY CURRENT vs.

EXTERNAL CLOCK FREQUENCY

100

500

MAX3110E-04

EXTERNAL CLOCK FREQUENCY (MHz)

SUPPLY CURRENT (µA)

2

400

300

200

MAX3110E
V

CC

= +5V

MAX3111E
V

CC

= +3.3V

70

0

0 0.20.1 0.6 0.7

0.8

1.0

MAX3111E

TX, RTS, DOUT OUTPUT CURRENT

vs. OUTPUT LOW VOLTAGE (V

CC

= +3.3V)

10

MAX3110E-05

VOLTAGE (V)

OUTPUT SINK CURRENT (mA)

0.3 0.50.4 0.9

60

50

40

30

20

RTS

TX

DOUT

90

80

0

0 0.20.1 0.6 0.7

0.8

1.0

MAX3110E

TX, RTS, DOUT OUTPUT CURRENT

vs. OUTPUT LOW VOLTAGE (V

CC

= +5V)

10

70

MAX3110E-06

VOLTAGE (V)

OUTPUT SINK CURRENT (mA)

0.3 0.50.4 0.9

60

50

40

30

20

RTS

TX

DOUT

MAX3110E/MAX3111E

SPI/MICROWIRE-Compatible UART and ±15kV ESD-

Protected RS-232 Transceivers with Internal Capacitors

_______________________________________________________________________________________ 9

Pin Description

Positive terminal of internal inverting charge-pump capacitor. Do not make any connection to this terminal.

C2+24

Negative terminal of internal inverting charge-pump capacitor. Do not make any connection to this terminal.

C2-25

-5.5V generated by the internal charge pump. Do not make any connection to this terminal.

V-26

GroundGND27
RS-232 Transmitter Output 2T2OUT28

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

IRQ

19

Hardware Shutdown Input. Drive SHDN low to shut down the RS-232 transmitters and charge pump. Drive
high for normal operation.

SHDN

20

+5.5V generated by the internal charge pump. Do not make any connection to this terminal.

V+21

Positive terminal of the internal voltage-doubler charge-pump capacitor. Do not make any connection to

this terminal.

C1+22

Negative terminal of the internal voltage-doubler charge-pump capacitor. Do not make any connection to

this terminal.

C1-23

SPI/MICROWIRE Serial-Data Input. Schmitt-trigger Input.DIN15
SPI/MICROWIRE Serial-Data Output. High impedance when CS is high.

DOUT16

SPI/MICROWIRE Serial-Clock Input. Schmitt-trigger input.SCLK17
UART Active-Low Chip-Select Input. DOUT goes high impedance when CS is high. IRQ, TX, and RTS are

always active. Schmitt-trigger input.

CS

18

UART Asynchronous Serial-Data (transmitter) OutputTX14

UART Crystal Connection. Leave X2 unconnected when using an external CMOS clock. See the

Crystals,

Oscillators, and Ceramic Resonators

section.

X29

UART Crystal Connection. X1 also serves as an external CMOS clock input. See the

Crystals, Oscillators,

and Ceramic Resonators

section.

X110

UART Clear-to-Send Active-Low Input. Read via the CTS bit.

CTS

11

UART Request-to-Send Active-Low Output. Controlled by the RTS bit. Also used to control the driver enable
in RS-485 networks.

RTS

12

UART Asynchronous Serial-Data (receiver) Input. The serial information received from the RS-232 receiver.
A transition on RX while in shutdown generates an interrupt (Table 1).

RX13

RS-232 Receiver Output 1, TTL/CMOSR1OUT5
RS-232 Receiver Input 1R1IN6
RS-232 Transmitter Output 1T1OUT7
Positive Supply VoltageV

CC

8

RS-232 Transmitter lnput 1, TTL/CMOST1IN4

RS-232 Transmitter lnput 2, TTL/CMOST2IN3

PIN

RS-232 Receiver Output 2, TTL/CMOSR2OUT2

RS-232 Receiver Input 2R2IN1

FUNCTIONNAME

MAX3110E/MAX3111E

SPI/MICROWIRE-Compatible UART and ±15kV ESD­Protected RS-232 Transceivers with Internal Capacitors

10 ______________________________________________________________________________________

Detailed Description

The MAX3110E/MAX3111E contain an SPI/QSPI/MICROWIRE­compatible UART and an RS-232 transceiver with two
drivers and two receivers. The UART is compatible with
SPI and QSPI for CPOL = 0 and CPHA = 0. The UART
supports data rates up to 230kbaud for standard UART
bit streams as well as IrDA and includes an 8-word
receive FIFO. Also included is a 9-bit-address recogni­tion interrupt.

The RS-232 transceiver has electrostatic discharge
(ESD) protection on the transmitter outputs and the
receiver inputs. The internal charge-pump capacitors
minimize the number of external components required.
The RS-232 transceivers meet EIA/TIA-232 specifica-

tions for VCCdown to the minimum supply voltage and
are guaranteed to operate for data rates up to 250kbps.

The UART and RS-232 functions operate as one device
or independently since the two functions share only
supply and ground connections.

UART

The universal asynchronous receiver transmitter
(UART) interfaces the SPI/QSPI/MICROWIRE-compati­ble synchronous serial data from a microprocessor (µP)
to asynchronous, serial-data communication ports (RS­232, IrDA). Figure 1 shows the MAX3110E/MAX3111E
functional diagram. Included in the UART function is an
SPI/QSPI/MICROWIRE interface, a baud-rate generator,
and an interrupt generator.

SPI

INTERFACE

INTERRUPT

LOGIC

Pr

RX SHIFT REGISTER

Pt

TX SHIFT REGISTER

T2OUT

T2IN

9

Pr RX BUFFER

Pt TX BUFFER

Pr RX FIFO

9

9

9

9

9

9

4

INTERNAL

5k

5k

INTERNAL

INTERNAL

INTERNAL

T1OUT

R2IN

T1IN

R2OUT

R1IN

V+

GND

V-

SHDN

IRQ

R1OUT

C1+

C1­C2+

C2-

V

CC

RX

X2

X1

TX

CTS
RTS

BAUD-RATE

GENERATOR

DOUT

SCLK

CS

DIN

I/O

CHARGE

PUMP

MAX3110E/MAX3111E

Figure 1. MAX3110E/MAX3111E Functional Diagram