MAX1747EUP Maxim Integrated Products, MAX1747EUP Datasheet - Page 8

• Manufacturer Part Number: MAX1747EUP
• Description: Charge Pumps
• Manufacturer: Maxim Integrated Products

Specifications of MAX1747EUP

• Function: Step Up, Step Down
• Output Voltage: 4.5 V to 5.5 V, +/- 35 V
• Output Current: 200 mA
• Maximum Operating Temperature: + 85 C
• Package / Case: TSSOP-20
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

The MAX1747 is an efficient triple-output power supply
for TFT LCD applications. The device contains one
high-power charge pump and two low-power charge
pumps. The MAX1747 charge pumps switch continu-
ously at a constant frequency, so the output noise con-
tains well-defined frequency components, and the
circuit requires much smaller external capacitors for a
Triple Charge-Pump TFT LCD
DC-DC Converter
8
_______________________________________________________________________________________
PIN
1, 2
10
11
12
13
14
15
16
17
18
19
20
3
4
5
6
7
8
9
NAME
TGND
SHDN
PGND
SUPM
DRVN
SUPN
DRVP
SUPP
INTG
GND
RDY
CXN
OUT
FBN
CXP
REF
FBP
FB
IN
Detailed Description
Must be connected to ground.
Active-Low Open-Drain Output. Indicates all outputs are ready. The R
Main Charge-Pump Feedback Input. Regulates to 1.25V nominal. Connect to the center of a
feedback resistive divider between the main output (OUT) and analog ground (GND).
Main Charge-Pump Integrator Output. If used, connect 1500pF to analog ground (GND). To disable
the integrator, connect to GND.
Supply Input. +2.7V to +4.5V input range. Powers only the logic and reference. Bypass to analog
ground (GND) with a 0.1µF capacitor as close to the pin as possible.
Analog Ground. Connect to power ground (PGND) underneath the IC.
Internal Reference Bypass Terminal. Connect a 0.22µF capacitor from this terminal to analog
ground (GND). External load capability to 50µA. REF is disabled in shutdown.
Positive Charge-Pump Feedback Input. Regulates to 1.25V nominal. Connect feedback resistive
divider to analog ground (GND).
Negative Charge-Pump Regulator Feedback Input. Regulates to 0V nominal. Connect feedback
resistive divider to the reference (REF).
Shutdown Input. Drive SHDN through an external resistor. When SHDN is pulled low, the device
turns off and draws only 0.1µA. OUT is also pulled low through an internal 10Ω resistor in shutdown
mode. When current is sourced into SHDN through R
input current sets the oscillator’s switching frequency:
Negative Charge-Pump Driver Output. Output high level is V
Negative Charge-Pump Driver Supply Voltage. Bypass to power ground (PGND) with a 0.1µF
capacitor.
Positive Charge-Pump Driver Output. Output high level is V
Positive Charge-Pump Driver Supply Voltage. Bypass to power ground (PGND) with a 0.1µF
capacitor.
Power Ground. Connect to analog ground (GND) underneath the IC.
Negative Terminal of the Main Charge-Pump Flying Capacitor
Main Charge-Pump Supply Voltage Input
Positive Terminal of the Main Charge-Pump Flying Capacitor
Main Charge-Pump Output. Bypass to power ground (PGND) with 10µF for a 1MHz application
(see Output Capacitor Selection). An internal 10Ω resistor discharges the output when the device
is shut down.
R
FREQ
(kΩ) = 45.5 (MHz / mA)
given output ripple. The adjustable switching frequency
is set by the current into the shutdown pin (see
Frequency Selection and Shutdown).
The main charge pump uses internal MOSFETs with
low R
output voltage of the main charge pump can be set up
to 5.5V with external resistors. The dual low-power
charge pumps independently regulate a positive output
ON
FUNCTION
to provide high output current. The adjustable
✕
FREQ
(V
ON
, the device activates, and the SHDN
SUPP
- 0.7V) / f
SUPN
and low level is PGND.
, and low level is PGND.
OSC
ON
is 125Ω (typ).
(MHz)
Pin Description