Bridge-Battery Backup Controllers

for Notebooks

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5

NAME

FUNCTION

1

ISET

Bridge-Battery Charge-Current Input. Connect a current-setting resistor from this input to a voltage

higher than the bridge battery. Maximum current rating is 10mA. Pulling ISET below 0.4V resets the

internal counter.

2

BBATT

Bridge-Battery Connection. Bridge-battery charger output.

PIN

3

LX

Step-Up DC-DC Converter N-Channel MOSFET Drain. The maximum operating range is 12V.

4

LBO

8

FULL

Open-Drain Bridge-Battery Full Indicator Output. When the internal timer reaches all 1sec, FULL

goes high impedance.

7

CCMD

Charge Command Input. When low with DCMD high, the internal switch from ISET to BBATT is

closed, charging the bridge battery. CCMD is inhibited if DCMD is low. The internal timer counts up

at a frequency set by the CC capacitor.

6

DCMD

Discharge Command Input. When low with CCMD high, the internal timer counts down at a

frequency set by the CD capacitor. When both DCMD and CCMD are low, discharge takes

precedence.

5

BBON

Bridge-Battery On Input. When high, the DC-DC converter turns off. When pulled low through an

external resistor, the resistor sets the peak inductor current. The inductor current is approximately

13

CD

Discharge Oscillator Capacitor Input. This capacitor sets the discharging oscillator frequency,

which determines the maximum time to decrement the counter from all 1s to all 0s. Calculate the

capacitor value as follows: CD (in nF) = 4.3 · discharge time (in hours).

12

CC

Charge Oscillator Capacitor Input. This capacitor programs the charging oscillator frequency,

which sets the time for the internal counter to reach all 1s. Determine the capacitor value by: CC

(in nF) = 4.3 · charge time (in hours).

11

GND

Ground

10

LBI

Low-Battery-Detector Input. When LBI falls below 1.8V, LBO goes low and sinks current. When LBI

goes above 2.0V, LBO goes high impedance. Hysteresis is typically 200mV.

9

FB

Feedback Input of Step-Up DC-DC Converter. Regulates to 2V. Connect feedback resistors to set

output voltage (Figure 2).

Pin Description

14

PGND

Power Ground and Step-Up DC-DC Converter N-Channel MOSFET Source

15

LRO

5V (MAX1612) or 3.3V (MAX1613) Linear-Regulator Output. Bypass to GND with a 1µF capacitor.

Maximum external load current is 10mA.

16

LRI

Linear-Regulator Supply Input