MAX1747 Datasheet, PDF (1/13 Pages) Maxim Integrated Products – Triple Charge-Pump TFT LCD DC-DC Converter

19-1788; Rev 0; 10/00
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Triple Charge-Pump TFT LCD
DC-DC Converter
General Description
The MAX1747 triple charge-pump DC-DC converter
provides the regulated voltages required by active
matrix thin-film transistor (TFT) liquid-crystal displays
(LCDs) in a low-profile TSSOP package. One high-
power and two low-power charge pumps convert the
+2.7V to +4.5V input supply voltage into three indepen-
dent output voltages.
The primary high-power charge pump generates an
output voltage (V_OUT) between 4.5V and 5.5V that is
regulated within ±1%. The low-power BiCMOS control
circuitry and the low on-resistance (R_ON) power
MOSFETs maximize efficiency. The adjustable switch-
ing frequency (200kHz to 2MHz) provides fast transient
response and allows the use of small low-profile ceram-
ic capacitors.
The dual low-power charge pumps independently regu-
late one positive output (V_POS) and one negative output
(V_NEG). These additional outputs use external diode
and capacitor multiplier stages (as many stages as
required) to regulate output voltages up to +35V and
-35V.
The constant switching frequency and a proprietary
regulation algorithm minimize output ripple and capaci-
tor sizes for all three charge pumps. The MAX1747 is
available in the ultra-thin TSSOP package (1.1mm max
height).
Applications
TFT Active-Matrix LCDs
Passive-Matrix Displays
Personal Digital Assistants (PDAs)
TOP VIEW
TGND 1
TGND 2
RDY 3
FB 4
INTG 5
IN 6
GND 7
REF 8
FBP 9
FBN 10
Pin Configuration
MAX1747
20 OUT
19 CXP
18 SUPM
17 CXN
16 PGND
15 SUPP
14 DRVP
13 SUPN
12 DRVN
11 SHDN
Features
o Adjustable Outputs
Up to +5.5V Main High-Power Output
Up to +35V Positive Charge-Pump Output
Down to -35V Negative Charge-Pump Output
o 200kHz to 2MHz Adjustable Switching Frequency
o +2.7V to +4.5V Input Supply
o Internal Power MOSFETs
o 0.1µA Shutdown Current
o Internal Soft-Start
o Power-Ready Output
o Internal Supply Sequencing
o Fast Transient Response
o Ultra-Thin Solution (No Inductors)
o Thin TSSOP Package (1.1mm max)
Ordering Information
PART
MAX1747EUP
TEMP. RANGE
-40°C to +85°C
PIN-PACKAGE
20 TSSOP
Typical Operating Circuit
INPUT
TO µC
SUPM
IN
SHDN
RDY
DRVN
CXP
CXN
OUT
SUPP
SUPN
FB
MAX1747
MAIN OUTPUT
NEGATIVE
OUTPUT
DRVP
FBN
REF
TGND
GND
FBP
INTG
PGND
POSITIVE
OUTPUT
TSSOP
________________________________________________________________ Maxim Integrated Products 1
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