MAX1613EEE-T Maxim Integrated, MAX1613EEE-T Datasheet - Page 6

• Manufacturer Part Number: MAX1613EEE-T
• Description: Battery Management
• Manufacturer: Maxim Integrated
• Series: MAX1612, MAX1613r

The MAX1612/MAX1613 manage the bridge battery
(auxiliary battery) in portable systems. These devices
consist of a timer block that monitors the charging
process, a linear regulator for supplying IC power and
external circuitry to the MAX1612/MAX1613, and a DC-
DC step-up converter that powers the system when the
main battery is removed (Figure 1). The boost DC-DC
converter reduces the number of bridge-battery cells
required to supply the system’s DC-DC converter.
When the main supply is present, the DC-DC converter
is inactive, reducing the drain on the main battery to
only 18µA. However, if the main battery voltage falls (as
detected by the low-battery comparator), the bridge
battery becomes the input source.
Bridge-Battery Backup Controllers
for Notebooks
Figure 1. Functional Diagram
6
_______________Detailed Description
TO EXTERNAL
_______________________________________________________________________________________
LOADS
C
C
CC
CD
LRO
GND
CC
CD
V
MAIN
OSCILLATOR
OSCILLATOR
DISCHARGE
CHARGE
LINEAR REGULATOR
REFERENCE
+3.3/+5V
2.0V
LRI
V
CHARGE
CHARGE/DISCHARGE
TIMER BLOCK
COUNTER
R
ISET
ISET
FULL
V
BBATT
The MAX1612/MAX1613 have an internal linear regula-
tor set at +5V (MAX1612) or +3.3V (MAX1613). The lin-
ear regulator can deliver a load up to 10mA, making it
capable of powering external components such as a
microcontroller (Figure 4). An undervoltage lockout fea-
ture disables the device when the input voltage falls
below the operating range, preventing the DC-DC con-
verter from inadvertently powering up.
The MAX1612/MAX1613 feature an internal counter
intended to track the charging and discharging
process. The counter tracks the charge on the bridge
battery, allowing trickle charge to terminate when the
maximum charge is achieved. The charging rate is
determined by current through the ISET switch, and
limited by the switch’s maximum current specification
as well as by the bridge cell’s charging capability. As
CCMD
BBATT
DCMD
MODULATION
FREQUENCY
CONTROL
PULSE-
BLOCK
BBON
1.8V/2.0V
MAX1612
MAX1613
R
BBON
N-CHANNEL
L1
LBO
PGND
LBI
LX
FB
D1
R1
R2
R3
TO MAIN
DC-DC
C
OUT