MAX1747EUP Maxim Integrated Products, MAX1747EUP Datasheet - Page 9

• 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

(V
puts use external diode and capacitor stages (as many
stages as required) to regulate output voltages above
+35V and under -35V.
A proprietary regulation algorithm minimizes output rip-
ple as well as capacitor sizes for all three charge
pumps. Also included in the MAX1747 are a precision
1.25V reference that sources up to 50µA, shutdown,
power-up sequencing, fault detection, and an active-
low open-drain ready output.
During the first half-cycle, the MAX1747 charges the
flying capacitor (CX) by connecting it between the sup-
ply voltage (V
charge is controlled by the variable N-channel on-resis-
tance. During the second half-cycle, the MAX1747 level
shifts the flying capacitor by stacking the voltage
Figure 1. Typical Application Circuit
POS
) and a negative output (V
V
IN
= 3.0V
1.0µF
10µF
V
-7V, 10mA
C IN
NEG
C6
SUPM
_______________________________________________________________________________________
) and ground (Figure 2). This initial
1.0µF
D3
D4
100k
C10
R7
R
280k
Main Charge Pump
100k
FREQ
0.22µF
D7
D8
0.1µF
R5
C REF
C5
NEG
). These two out-
0.1µF
49.9k
0.1µF
C9
R6
C1
Triple Charge-Pump TFT LCD
SHDN
DRVN
TGND
GND
IN
RDY
FBN
REF
SUPM
MAX1747
SUPN
DRVP
PGND
SUPP
across CX on top of the supply voltage. This transfers
the sum of the two voltages to the output capacitor
(C
The MAX1747 contains two individual low-power
charge pumps. Using a single stage, the first charge
pump inverts the supply voltage (V
a regulated negative output voltage. The second
charge pump doubles the supply voltage (V
provides a regulated positive output voltage. The
MAX1747 contains internal P-channel and N-channel
MOSFETs to control the power transfer. The internal
MOSFETs switch at a constant frequency set by the
current into the shutdown pin (see Frequency Selection
and Shutdown).
INTG
CXN
CXP
OUT
FBP
FB
OUT
).
0.1µF
0.1µF
C3
C7
C11
0.1µF
CX
0.47µF
C
1500pF
INTG
C12
0.1µF
DC-DC Converter
Dual Charge-Pump Regulators
D2
D1
C
(2) 4.7µF
OUT
R4
49.9k
D6
D5
432k
R3
R1
150k
R2
49.9k
SUPN
V
+12V, 5mA
C8
1.0µF
POS
) and provides
C4
1.0µF
+5V, 200mA
V
OUT
SUPP
) and
9