MAX1678 Datasheet, PDF (6/12 Pages) Maxim Integrated Products – 1-Cell to 2-Cell, Low-Noise, High-Efficiency, Step-Up DC-DC Converter

1-Cell to 2-Cell, Low-Noise,
High-Efficiency, Step-Up DC-DC Converter
Typical Operating Characteristics (continued)
(Circuit of Figure 7 (Fixed Mode, 3.3V) or Figure 8 (Adjustable Mode), T_A = +25°C, unless otherwise noted.)
SWITCHING WAVEFORM
LOAD-TRANSIENT RESPONSE
A
A
B
B
C
5µs/div
V_OUT = 3.3V, V_BATT = 1.2V, I_LOAD = 10mA, C_OUT = 10µF,
L1 = SUMIDA CD43-470
A: LX, 2V/div B: V_OUT, 50mV/div AC COUPLED
C: INDUCTOR CURRENT, 100mA/div
LINE-TRANSIENT RESPONSE
C
100µs/div
V_OUT = 3.3V, V_BATT = 1.2V, C_OUT = 10µF,
L1 = SUMIDA CD43-470,
A: V_OUT, 50mV/div, AC COUPLED B: INDUCTOR CURRENT,
C: LOAD, 2mA to 12mA
100mA/div
POWER-UP RESPONSE
A
A
B
B
C
200µs/div
V_OUT = 3.3V, V_BATT = 1.2V, I_LOAD = 10mA, C_OUT = 10µF,
L1 = SUMIDA CD43-470
A: V_OUT, 50mV/div, AC COUPLED B: V_IN, 1V/div, 1.2V to 2.2V
100µs/div
V_OUT = 3.3V, V_BATT = 1.2V, I_LOAD = 10mA, C_OUT = 10µF,
L1 = SUMIDA CD43-470
A: V_OUT, 1V/div B: INDUCTOR CURRENT, 100mA/div
C: SHDN, 5V/div
Pin Description
PIN NAME
FUNCTION
1
BATT Battery-Power Input
2
PFI
Power-Fail Input. When the voltage at PFI is below 614mV, PFO sinks current.
3
PFO
Open-Drain Power-Fail Output. PFO sinks current when PFI is below 614mV.
4
SHDN Active-Low Shutdown. Connect SHDN to BATT for normal operation.
5
FB
Dual-Mode Feedback Input. Connect FB to GND for fixed-output operation (3.3V). Connect FB to a feed-
back-resistor network for adjustable output voltage operation (2V to 5.5V). FB regulates to 1.23V.
6
GND Ground
7
LX
N-Channel MOSFET Switch Drain and P-Channel Synchronous-Rectifier Drain
8
OUT
Power Output and IC Power Input (bootstrapped). OUT is the feedback input for 3.3V operation. Connect
the filter capacitor close to OUT.
6 _______________________________________________________________________________________