Rainbow Electronics MAX1621 - Manual

General Description
The MAX1620/MAX1621 convert a 1.8V to 20V battery
voltage to a positive or negative LCD backplane bias
voltage. Backplane bias voltage can be automatically
disabled when the display logic voltage is removed,
protecting the display. These devices use very little PC
board area, come in ultra-small QSOP packages, and
require only small, low-profile external components.
Output voltage can be set to a desired positive or nega-
tive voltage range with external resistors, and adjusted
over that range with the on-board digital-to-analog con-
verter (DAC) or with a potentiometer. The MAX1620/
MAX1621 include a 5-bit DAC, allowing digital software
control of the bias voltage. The MAX1620 uses up/down
digital signaling to adjust the DAC, and the MAX1621
uses the System Management Bus (SMBus™) 2-wire
serial interface.
These devices use a low-cost, external, N-channel MOSFET
power switch or NPN transistor, and can be configured
for positive or negative output voltages. Operating cur-
rent is a low 150µA, typically provided from a display’s
logic supply of 3.0V to 5.5V. The MAX1620/MAX1621 are
available in a 16-pin QSOP package.
Applications
Notebook Computers
Palmtop Computers
Personal Digital Assistants
Portable Data-Collection Terminals
Features
♦ 1.8V to 20V Battery Input Voltage
♦ Automatic Disable when Display Logic
is Shut Down
♦ Extremely Small QSOP Package
♦ 32-Level Internal DAC
♦ SMBus Serial Interface (MAX1621)
♦ Positive or Negative Output Voltage
MAX1620/MAX1621
Digitally Adjustable LCD Bias Supplies
________________________________________________________________ Maxim Integrated Products 1
PART
MAX1620 EEE
MAX1621 EEE -40°C to +85°C
-40°C to +85°C
TEMP. RANGE PIN-PACKAGE
16 QSOP
16 QSOP
EVALUATION KIT MANUAL
FOLLOWS DATA SHEET
Ordering Information
19-1214; Rev 1; 1/98
LX
DHI
DLO
PGND
DOUT
FB
V DD
POL
SHDN
DN
UP
REF
AGND
MAX1620
12.5V
TO
23.5V OUT
2V TO
12V
3V TO
5.5V
ON / OFF
DOWN
UP
LCDON POK
BATT
Typical Operating Circuit
SMBus is a trademark of Intel Corp.
Pin Configuration
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
DHI
DLO
LX
PGND
AGND
V DD
DOUT
FB
DN (SDA)
UP (SCL)
BATT
SHDN (SUS)
POK
REF
POL
LCDON
TOP VIEW
MAX1620
MAX1621
QSOP
( ) ARE FOR MAX1621 ONLY.
8
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.