MAX3325 Datasheet, PDF (1/12 Pages) Maxim Integrated Products – 3V Dual RS-232 Transceiver with LCD Supply and Contrast Controller

19-1573; Rev 0; 10/99
3V Dual RS-232 Transceiver with
LCD Supply and Contrast Controller
General Description
The MAX3325 integrates a two-transmitter, two-receiver
RS-232 transceiver with an LCD supply plus tempera-
ture-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 supply-
ing 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, tai-
loring power consumption for battery-powered equip-
ment. The MAX3325 is available in 28-pin SSOP and
narrow DIP packages.
Features
o +3.0V to +3.6V Single-Supply Operation
o Provides 5.0V Regulated Output at 11mA in
3V Systems
o 6-Bit DAC with Up/Down Interface for LCD
Contrast Adjustment
o Selectable Positive or Negative LCD Bias
o Meets EIA-232E Specifications at 250kbps—
Guaranteed
o 1µA Shutdown Mode
o Uses Small 0.22µF Capacitors—No Inductors
Required
o Temperature Sensor for LCD Contrast
Compensation
o Simple, Flexible Design Procedure for a Broad
Range of LCD Displays
Ordering Information
PART
MAX3325CAI
MAX3325CNI
MAX3325EAI
MAX3325ENI
TEMP. RANGE
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
28 SSOP
28 Narrow Plastic DIP
28 SSOP
28 Narrow Plastic DIP
Applications
PDAs and Palmtop Computers
Handy Terminals
GPS Receivers
Hand-Held Medical Equipment
Industrial Test Equipment
Typical Operating Circuit appears at end of data sheet.
Pin Configuration
TOP VIEW
C2+ 1
C2- 2
V- 3
R2IN 4
R1IN 5
R1OUT 6
R2OUT 7
VL 8
LCD 9
TEMP 10
REF- 11
FB 12
REF+ 13
DAC 14
MAX3325
28 C1+
27 V+
26 VDD
25 GND
24 C1-
23 REG
22 T1OUT
21 T2OUT
20 T1IN
19 T2IN
18 SD232
17 SDLCD
16 DOWN
15 UP
SSOP/DIP
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