MAX1612 Datasheet, PDF (5/12 Pages) Maxim Integrated Products – Bridge-Battery Backup Controllers for Notebooks

Bridge-Battery Backup Controllers
for Notebooks
Pin Description
PIN
NAME
FUNCTION
Bridge-Battery Charge-Current Input. Connect a current-setting resistor from this input to a voltage
1
ISET
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.
3
LX
Step-Up DC-DC Converter N-Channel MOSFET Drain. The maximum operating range is 12V.
4
LBO
Open-Drain Low-Battery Detector Output. When V_LBI falls below 1.8V, LBO sinks current. When
V_LBI rises above 2.0V, LBO becomes high impedance.
Bridge-Battery On Input. When high, the DC-DC converter turns off. When pulled low through an
5
BBON
external resistor, the resistor sets the peak inductor current. The inductor current is approximately
42,000 times the current in the external resistor (R_BBON).
Discharge Command Input. When low with CCMD high, the internal timer counts down at a
6
DCMD
frequency set by the CD capacitor. When both DCMD and CCMD are low, discharge takes
precedence.
Charge Command Input. When low with DCMD high, the internal switch from ISET to BBATT is
7
CCMD
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.
8
FULL
Open-Drain Bridge-Battery Full Indicator Output. When the internal timer reaches all 1sec, FULL
goes high impedance.
9
FB
Feedback Input of Step-Up DC-DC Converter. Regulates to 2V. Connect feedback resistors to set
output voltage (Figure 2).
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.
11
GND
Ground
Charge Oscillator Capacitor Input. This capacitor programs the charging oscillator frequency,
12
CC
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).
Discharge Oscillator Capacitor Input. This capacitor sets the discharging oscillator frequency,
13
CD
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).
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
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