Maxim MAX3325ENI, MAX3325EAI, MAX3325CNI, MAX3325CAI Datasheet

For free samples & the latest literature: http://www.maxim-ic.com, or phone [phone].
For small orders, phone [phone].

General Description

The MAX3325 integrates a two-transmitter, two-receiver
RS-232 transceiver with an LCD supply plus tempera­ture-compensated contrast control. It is intended for
small 3V instruments requiring a 5V supply for either
logic or an LCD display, an adjustable bias signal for
contrast, LCD temperature compensation, and an
RS-232 interface for serial communications.

The 5V supply is a regulated charge pump followed by
a low-dropout (LDO) linear regulator capable of supply­ing 11mA for the 5V LCD power.

The MAX3325 has an internal 6-bit digital-to-analog
converter (DAC) providing 64 contrast levels, plus an
internal temperature sensor that compensates the
LCD’s contrast for changes in ambient temperature.
The LCD contrast can be designed for any voltage
range from -5V to +2V.

The MAX3325’s 250kbps RS-232 transceiver meets all
EIA-232E specifications with input voltages from +3.0V
to +3.6V. Both the RS-232 section and the LCD supply
circuitry can be independently placed in shutdown, tai­loring power consumption for battery-powered equip­ment. The MAX3325 is available in 28-pin SSOP and
narrow DIP packages.

Applications

PDAs and Palmtop Computers
Handy Terminals
GPS Receivers
Hand-Held Medical Equipment
Industrial Test Equipment

Features

♦ +3.0V to +3.6V Single-Supply Operation
♦ Provides 5.0V Regulated Output at 11mA in

3V Systems

♦ 6-Bit DAC with Up/Down Interface for LCD

Contrast Adjustment

♦ Selectable Positive or Negative LCD Bias
♦ Meets EIA-232E Specifications at 250kbps—

Guaranteed

♦ 1µA Shutdown Mode
♦ Uses Small 0.22µF Capacitors—No Inductors

Required

♦ Temperature Sensor for LCD Contrast

Compensation

♦ Simple, Flexible Design Procedure for a Broad

Range of LCD Displays

MAX3325

3V Dual RS-232 Transceiver with

LCD Supply and Contrast Controller

________________________________________________________________

Maxim Integrated Products

1

19-1573; Rev 0; 10/99

Typical Operating Circuit appears at end of data sheet.

Pin Configuration

Ordering Information

PART

MAX3325CAI
MAX3325CNI
MAX3325EAI -40°C to +85°C

0°C to +70°C

0°C to +70°C

TEMP. RANGE PIN-PACKAGE

28 SSOP
28 Narrow Plastic DIP
28 SSOP

MAX3325ENI -40°C to +85°C 28 Narrow Plastic DIP

TOP VIEW

1

C2+

2

C2-

3

V-

4

R2IN

5

R1IN
R1OUT
R2OUT

LCD

TEMP

REF-

REF+

DAC

MAX3325

6
7
8

V

L

9
10
11
12

FB

13
14

SSOP/DIP

28

C1+

27

V+

26

V

DD

25

GND

24

C1-

23

REG

22

T1OUT

21

T2OUT

20

T1IN

19

T2IN

18

SD232

17

SDLCD

16

DOWN

15

UP

MAX3325

3V Dual RS-232 Transceiver with
LCD Supply and Contrast Controller

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VDD= +3.0V to +3.6V, VL= +3.3V, circuit and components of Figure 1, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values

are at V

DD

= +3.3V, 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.

VDD, VLto GND........................................................-0.3V to +6V

LCD, REF-, TEMP to GND.............................-6V to (V

DD

+ 0.3V)

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

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

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

REF+, FB, R_OUT to GND ............................-0.3V to (V

L

+ 0.3V)
Input Voltages

T_OUT, SDLCD, SD232, UP, DOWN to GND.......-0.3V to +6V

R_IN to GND....................................................................±25V

Output Voltages

T_OUT to GND.................................................................±13V

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

L

+ 0.3V)

REG to GND.........................................................-0.3V to +6V

Short-Circuit Duration (T_OUT, REF+, REF-) .............Continuous

Continuous Output Current

REG.................................................................................75mA

LCD.................................................................................40mA

Continuous Power Dissipation

28-Pin SSOP (derate 9.52mW/°C above +70°C) .........762mW

28-Pin NDIP (derate 14.3mW/°C above +70°C) ........1143mW

Operating Temperature Range

MAX3325C_I.......................................................0°C to +70°C

MAX3325E_I ....................................................-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 cannot exceed 13V.

V

FB

= 0, CMOS input

3V < VDD< 3.6V

1 transmitter loaded with
5kΩ, TA= +25°C

I

TEMP

< 22µA

TA= +25°C

Guaranteed monotonic
No load

No load, VDD= VL= 3.3V, TA= +25°C

No load, VDD= VL= 3.3V, TA= +25°C

CONDITIONS

nA-10 0 10Input Leakage Current (Note 2)

mV-20 0 20Feedback Regulation Point

mA50Short-Circuit Current

mV650Line Regulation

4.7 5 5.3

mV/°C-18

TEMP Voltage Temperature
Coefficient

V-3.2TEMP Output

kΩ35 50 65Output Impedance

mV-15 0 10Zero-Scale Voltage

V1.13 1.2 1.27Full-Scale Voltage

Bits6

µA0.5 10VLSupply Current

mA24VDDSupply Current

UNITSMIN TYP MAXPARAMETER

SD232, SDLCD = GND; all input pins = GND or VDD;
V

DD

= VL= 3.3V; TA= +25°C

µA0.5 10VDDShutdown Supply Current

V

LCD

= -4.0V, load = 0 to -3mA mV20LCD Load Regulation (Note 3)

V

5

REG Output Voltage

0 < V

DAC

< V

REF

+, I

DAC

≤ 10µA

No load

V

CC

≥ 3.15V, I

REG

= 0 to

11mA
V

CC

≥ 3.0V, I

REG

= 0 to

7mA

DC CHARACTERISTICS

DIGITAL-TO-ANALOG CONVERTER

TEMPERATURE SENSOR

POSITIVE LINEAR REGULATOR

NEGATIVE LINEAR REGULATOR—LCD BIAS

Resolution

MAX3325

3V Dual RS-232 Transceiver with

LCD Supply and Contrast Controller

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VDD= +3.0V to +3.6V, VL= +3.3V, circuit and components of Figure 1, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values

are at V

DD

= +3.3V, TA= +25°C.)

CONDITIONS UNITSMIN TYP MAXPARAMETER

LCD Line Regulation 3V < VDD< 3.6V, V

LCD

= -4.0V 10 mV

LCD Adjustment Range Load = -3mA -5 +2 V

Output Voltage R

REF

+ = 10kΩ 1.16 1.21 1.26 V
Load Regulation Load = 12µA to 62µA (sourcing current) 4 mV
Short-Circuit Current 5 mA

Output Voltage No load -1.14 -1.21 -1.28 V
Load Regulation Load = 0 to 50µA (sinking current) 35 mV
Short-Circuit Current 0.125 mA

Logic Threshold High 2 V
Logic Threshold Low 0.8 V
Input Current VIN= GND or V

DD

-1 1 µA

Output Voltage Low I

SINK

= 1.6mA 0.4 V

Output Voltage High I

SOURCE

= 1.0mA

0.8 · V

L

V

Input Voltage Range -25 +25 V
Input Threshold Low TA= +25°C, VDD= 3.3V 0.6 V
Input Threshold High TA= +25°C, VDD= 3.3V 2.4 V
Input Hysteresis 0.3 V
Input Resistance -15V < V

R_IN

< +15V, TA= +25°C 357kΩ

Output Voltage Swing All outputs loaded with 3kΩ to ground ±5 ±5.4 V
Output Resistance VDD= VL= V+ = V- = 0, V

OUT

= ±2V 300 10M Ω

Short-Circuit Current ±35 ±60 mA
Output Leakage Current

VDD= 0 or 3V to 3.6V, V

OUT

= ±12V, transmitters

disabled

±25 µA

POSITIVE REFERENCE VOLTAGE

NEGATIVE REFERENCE VOLTAGE

LOGIC INPUTS (SD232, SDLCD, T1IN, T2IN, UP, DOWN)

TRANSMITTER OUTPUTS

RECEIVER INPUTS

RECEIVER OUTPUTS

MAX3325

3V Dual RS-232 Transceiver with
LCD Supply and Contrast Controller

4 _______________________________________________________________________________________

Typical Operating Characteristics

(VDD= VL= +3.3V, circuit and components of Figure 1, all transmitters loaded with 3kΩ,TA= +25°C, unless otherwise noted.)

TIMING CHARACTERISTICS

(VDD= +3.0V to +3.6V, VL= +3.3V, circuit and components of Figure 1, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values

are at V

DD

= +3.3V, TA= +25°C.)

Note 2: Guaranteed by design and not production tested.
Note 3: No load on REG or transmitter outputs.

t

PLH

300

PARAMETER SYMBOL MIN TYP MAX UNITS

Transition-Region Slew Rate 630V/µs

Transmitter Skew | t

PLH

- t

PHL

| 200 ns

Receiver Propagation Delay

Maximum Data Rate 250 kbps

t

PHL

300

ns

Receiver Skew | t

PLH

- t

PHL

| 300 ns

CONDITIONS

VDD= 3.3V, TA= +25°C, RL= 3kΩ to
7kΩ, C

L

= 150pF to 1000pF, measured

from +3V to -3V or -3V to +3V

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

Receiver input to receiver output,
CL= 150pF

TRANSMITTER OUTPUT VOLTAGE vs.

6
5
4
3
2
1
0

-1

-2

-3

-4

TRANSMITTER OUTPUT VOLTAGE (V)

-5

-6

LOAD CAPACITANCE

V

OUT+

T1 TRANSMITTING AT 250kbps
T2 TRANSMITTING AT 15.6kbps

V

OUT-

0 20001000 3000 4000 5000

LOAD CAPACITANCE (pF)

MAX3325toc01

SLEW RATE vs. LOAD CAPACITANCE

14

12

10

8

6

SLEW RATE (V/µs)

4

2

FOR DATA RATES
UP TO 250kbps

0

0 20001000 3000 4000 5000

LOAD CAPACITANCE (pF)

MAX3325toc02

SUPPLY CURRENT (mA)

CAPACITANCE (T1 = 20kbps)

50

40

30

20

10

0

0 1000 2000 3000 4000 5000

SUPPLY CURRENT vs. LOAD

T2 = 250kbps

T2 = 120kbps

T2 = 20kbps

LOAD CAPACITANCE (pF)

MAX3325toc03