MAX1613EEE-T Maxim Integrated, MAX1613EEE-T Datasheet - Page 9

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

Figure 4. Microcontroller-Based Application
The MAX1612/MAX1613 feature a low-battery com-
parator with a factory-preset 1.8V threshold. This com-
parator is intended to monitor the main high-voltage
battery. As the voltage falls below 1.8V, the open-drain
LBO output sinks current. With 200mV of hysteresis, the
output will not go high until V
can easily be connected to BBON to start the DC-DC
converter when V
Figure 3). Figure 4 shows an application using a micro-
controller, where LBO alerts the microcontroller to the
falling voltage and pulls BBON low through an external
resistor to start the DC-DC converter while also pulling
DCMD low to start the counter.
The BBON input serves two functions: setting the peak
LX switch current, and enabling the DC-DC converter.
The control signal is normally applied to R
than at the pin itself. The peak LX switch current is
directly proportional to and 42,000 times greater than
the current through R
Characteristics ). The BBON pin is internally regulated
*OPTIONAL, TO RESET COUNTER
MICROCONTROLLER
V
CC
Low-Battery Comparator (LBI,
I/O
I/O
I/O
I/O
I/O
I/O
BATTERY
LBI
_______________________________________________________________________________________
BRIDGE
< 1.8V (stand-alone application,
470k
BBON
BBON Control Input
(see Typical Operating
470k
LBI
2N7002*
Bridge-Battery Backup Controllers
250k
exceeds 2.0V. LBO
47 F
1 F
BBON
0.01 F
LRO
LBO
FULL
BBON
DCMD
CCMD
CC
LBO )
rather
MAX1612
MAX1613
BBATT
CD
0.1 F
to 2V, so that when the control input is forced low, the
voltage across R
When driving BBON from external logic, ensure the low
state has minimal noise. Otherwise, drive R
an N-channel FET whose source is returned directly to
GND (Figure 2).
The following section refers to the Functional Diagram
of Figure 1.
Step 1: Select the output voltage and maximum output
current for the boost DC-DC converter. Generally,
choose an output voltage high enough to run the main
system’s buck DC-DC converters. Assuming the maxi-
mum battery capacity is 50mAh (Sanyo 1.2V N-50AAA),
the following equations can help the design process:
PGND
I
GND
PEAK
ISET
LX
LBI
FB
15 H
= 2 · I
0.33 F
OUT
Applications Information
BBON
MBR0530
· (V
I
IN
for Notebooks
OUT
2.4k
is 2V.
= 0.5 · I
BATTERY
20 F
MAIN
+ V
D
PEAK
) / (V
Design Procedure
BBATT
750k
35.2k
479.1k
- V
BBON
(MAX1630)
RDSON
SYSTEM
DC-DC
with
)
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