SP6644_05 Datasheet, PDF (7/15 Pages) Sipex Corporation – Single/Dual Alkaline Cell, High Efficiency Boost DC-DC Regulator

Refer to the circuit in Figure 28, T_AMB = +25^oC, unless otherwise noted.
SDN
2V/div
Li
0.5A/div
V_OUT, V_BATT
1V/div
PERFORMANCE CHARACTERISTICS
VBATT ¹
BATTLO 2
RLIM 3
SHDN 4
SP6644
SP6645
8 VOUT
7 LX
6 GND
5 FB
Figure 25. Shutdown Response and Inductor Current,
Vout=3.3V, Vbatt=1.3V, Rlim=2.5k, Rload=550 Ohms,
Li=22uH Sumida CD43
Figure 26. Pinout for the SP6644/6645
PIN DESCRIPTION
NAME
FUNCTION
PIN NO.
V_BATT Battery Supply. This pin ties to the sensor input of the BATTLO comparator.
1
BATTLO
Open-Drain Battery Low Output. When the voltage drops below 1V for the SP6644 or
2V for the SP6645, BATTLO sinks current.
2
Resistor Programmable Inductor Peak Current. Connecting a resistor from this pin to
R
LIM
ground programs the inductor peak current where ^IPEAK ⁼
1400
R_LIM
3
SHDN Active-LOW Shutdown Input. Connect to V_BATT for normal operation.
4
Feedback Input. Input for adjustable-output operation. Connect this input pin to an
FB
external resistor voltage divider between V_OUT and GND. Connect to GND for fixed-
5
output operation.
GND Connect to the lowest circuit potential, typically ground.
6
LX
Coil. An inductor is connected from V_BATT to the N-Channel MOSFET switch drain and
the P-Channel synchronous-rectifier drain through this pin.
7
V_OUT
Power Output. Feedback input for fixed 3.3V operation and IC power input. Connect
filter capacitor close to V_OUT.
8
Table 1. SP6644/6645 Pin Descriptions
Date: 11/30/04
SP6644/6645 High Efficiency Boost Regulator
7
© Copyright 2004 Sipex Corporation