Rainbow Electronics MAX1703 User Manual
Page 7
MAX1703
1-Cell to 3-Cell, High-Power (1.5A),
Low-Noise, Step-Up DC-DC Converter
_______________________________________________________________________________________
7
Pin Description
_________________________________Typical Operating Characteristics (continued)
(V
IN
= +3.6V, V
OUT
= 5V, T
A
= +25°C, unless otherwise noted.)
1ms/div
V
IN
= 3.6V, V
OUT
= 5V, C
OUT
= 470
µ
F,
PULSE WIDTH = 577
µ
s, LOAD CURRENT = 100mA TO 1A
V
OUT
(100mV/div)
I
LOAD
(0.5A/div)
GSM LOAD-TRANSIENT RESPONSE
MAX1703-12
2ms/div
V
IN
= 1.2V, V
OUT
= 3.3V, C
OUT
= 470
µ
F,
PULSE WIDTH = 416
µ
s, LOAD CURRENT = 50mA TO 400mA
V
OUT
(100mV/div)
I
LOAD
(0.2A/div)
DECT LOAD-TRANSIENT RESPONSE
MAX1703-13
PIN
Dual-Mode™ Feedback Input. Connect FB to ground to set a fixed output voltage of +5V. Connect a
divider between the output voltage and GND to set the output voltage from 2.5V to 5.5V.
FB
2
Reference Output. Bypass with a 0.22µF bypass capacitor to GND.
REF
1
FUNCTION
NAME
DC-DC Converter Output. Power source for the IC.
OUT
4
Power-Good Comparator Input. Threshold is 1.250V, with 1% hysteresis on the threshold’s rising edge.
POKIN
3
Power-Good Comparator Output. This open-drain N-channel output is low when V
POKIN
< 1.250V.
POK
8
Gain-Block Output. This open-drain output sinks current when V
AIN
< V
REF
.
AO
7
Gain-Block Input. When AIN is low, AO sinks current. The nominal transconductance from AIN to AO is
10mmhos.
AIN
6
Ground
GND
5
Source of P-Channel Synchronous Rectifier MOSFET Switch. Connect an external Schottky diode from LXN
and LXP to POUT.
POUT
13, 15
Source of N-Channel Power MOSFET Switch
PGND
10, 12
On/Off Input. When ON is low, the IC turns on.
ON
16
Switch-Mode Selection and External-Clock Synchronization Input:
•
CLK/SEL = Low: Low-power, low-quiescent-current PFM mode. Delivers up to 10% of full load current.
•
CLK/SEL = High: High-power PWM mode. Full output power available. Operates in low-noise, constant-
frequency mode.
•
CLK/SEL = External Clock: High-power PWM mode with the internal oscillator synchronized to the exter-
nal CLK
Turning on with CLK/SEL = 0V also serves as a soft-start function, since peak inductor current is limited to
25% of that allowed in PWM mode.
CLK/SEL
9
Dual Mode is a trademark of Maxim Integrated Products.
Drain of N-Channel Power Switch. Connect LXP to LXN.
LXN
11
Drain of P-Channel Synchronous Rectifier. Connect LXP to LXN.
LXP
14