Rainbow Electronics MAX1747 - Manual

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or visit Maxim’s website at www.maxim-ic.com.
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).
MAX1747
Triple Charge-Pump TFT LCD
DC-DC Converter
________________________________________________________________ Maxim Integrated Products 1
20
19
18
17
16
15
14
13
1
2
3
4
5
6
7
8
OUT
CXP
SUPM
CXN FB
RDY
TGND
TGND
TOP VIEW
PGND
SUPP
DRVP
SUPN REF
GND
IN
INTG
12
11
9
10
DRVN
SHDN FBN
FBP
MAX1747
TSSOP
Pin Configuration
19-1788; Rev 0; 10/00
Ordering Information
PART TEMP. RANGE PIN-PACKAGE
MAX1747EUP -40 °C to +85°C 20 TSSOP
Features
♦ Adjustable Outputs
Up to +5.5V Main High-Power Output
Up to +35V Positive Charge-Pump Output
Down to -35V Negative Charge-Pump Output
♦ 200kHz to 2MHz Adjustable Switching Frequency
♦ +2.7V to +4.5V Input Supply
♦ Internal Power MOSFETs
♦ 0.1µA Shutdown Current
♦ Internal Soft-Start
♦ Power-Ready Output
♦ Internal Supply Sequencing
♦ Fast Transient Response
♦ Ultra-Thin Solution (No Inductors)
♦ Thin TSSOP Package (1.1mm max)
Applications
TFT Active-Matrix LCDs
Passive-Matrix Displays
Personal Digital Assistants (PDAs)
IN
FB
SUPN
DRVP
FBP
PGND
DRVN
GND
TGND
MAX1747
SHDN
RDY
FBN
REF
INPUT
TO µC
SUPM
MAIN OUTPUT
POSITIVE
OUTPUT
INTG
CXP
CXN
OUT
SUPP
NEGATIVE
OUTPUT
Typical Operating Circuit
EVALUATION KIT
AVAILABLE