19-4785; Rev 0; 11/98
ANUAL
N KIT M EET
ATIO
SH
EVALU
S DATA
OLLOW
F
Bridge-Battery Backup Controllers
for Notebooks
Features
o
Reduce Battery Size and Cost
o
Four Key Circuit Blocks
Adjustable Boost DC-DC Converter
NiCd/NiMH Trickle Charger
Always-On Linear Regulator (+28V Input)
Low-Battery Detector
o
Low 18µA Quiescent Current
o
Selectable Charging/Discharging Rates
o
Preset Linear-Regulator Voltage
5V (MAX1612)
3.3V (MAX1613)
o
4V to 28V Main Input Voltage Range
o
Internal Switch Boost Converter
o
Small 16-Pin QSOP Package
General Description
The MAX1612/MAX1613 manage the bridge battery
(sometimes called a hot-swap or auxiliary battery) in
portable systems such as notebook computers. They
feature a step-up DC-DC converter that boosts 2-cell or
3-cell bridge-battery voltages up to the same level as
the main battery. This voltage boosting technique
reduces the number of cells otherwise required for a 6-
cell plus diode-OR bridging scheme, reducing overall
size and cost. Another key feature is a trickle-charge
timer that minimizes battery damage caused by con-
stant charging and eliminates trickle-charge current
drain on the main battery once the bridge battery is
topped off.
These devices contain a highly flexible collection of
independent circuit blocks that can be wired together
in an autonomous stand-alone configuration or used in
conjunction with a microcontroller. In addition to the
boost converter and charge timer, there is a micropow-
er linear regulator (useful for RTC/CMOS backup as
well as for powering a microcontroller) and a high-pre-
cision low-battery detection comparator.
The two devices differ only in the preset linear-regulator
output voltage: +5.0V for the MAX1612 and +3.3V for
the MAX1613. Both devices come in a space-saving
16-pin QSOP package.
MAX1612/MAX1613
Ordering Information
PART
MAX1612EEE
MAX1613EEE
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
16 QSOP
16 QSOP
Applications
Notebook Computers
Portable Equipment
Backup Battery Applications
Typical Operating Circuit
TOP VIEW
MAIN BATTERY
OR
WALL
ADAPTER
Pin Configuration
ISET 1
BBATT 2
LRI
DC-DC
OUTPUT
V+
16 LRI
15 LRO
14 PGND
LX 3
LBO 4
BBATT
AUXILIARY
BRIDGE
BATTERY
MAX1612
MAX1613
APPLICATION
CIRCUIT
MAX1630
+3.3V
+5V
BBON 5
DCMD 6
MAX1612
MAX1613
13 CD
12 CC
11 GND
10 LBI
9
FB
DC-DC
CONVERTER
CCMD 7
FULL 8
V
CPU
QSOP
________________________________________________________________
Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
Bridge-Battery Backup Controllers
for Notebooks
MAX1612/MAX1613
ABSOLUTE MAXIMUM RATINGS
LRI, ISET to GND....................................................-0.3V to +30V
LX to GND ..............................................................-0.3V to +14V
PGND to GND .......................................................-0.3V to +0.3V
BBATT, LRO,
CCMD, DCMD,
FULL,
BBON,
LBO
to GND ..........................................................-0.3V to +6V
CC, CD, LBI, FB to GND...........................-0.3V to (V
LRO
+ 0.3V)
FB, LBI, ISET, and BBATT Current......................................50mA
LRO Output Current ...........................................................50mA
Continuous Power Dissipation (T
A
= +70°C)
QSOP (derate 8.30mW/°C above +70°C) .................... 667mW
Operating Temperature Range
MAX1612/MAX1613EEE ...................................-40°C to +85°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10sec) ............................ +300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(V
LRI
= V
ISET
= 20V,
CCMD
=
DCMD
=
BBON
= LRO, V
BBATT
= 3V, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at
T
A
= +25°C.) (Note 1)
PARAMETER
Linear-Regulator Input Voltage
Range
Linear-Regulator Quiescent
Current
SYMBOL
V
LRI
MAX1612
MAX1613
V
BBON
≥
2V
I
LRI
V
DCMD
= 0, R
BBON
= 1MΩ to GND
(boost converter on)
5.7V
≤
V
LRI
≤
28V
(MAX1612)
4V
≤
V
LRI
≤
28V
(MAX1613)
4.7
3.1
CONDITIONS
MIN
5.7
4
18
42
5.0
3.3
TYP
MAX
28
28
28
58
5.3
µA
UNIT
V
Linear-Regulator Output Voltage
V
LRO
0
≤
I
LRO
≤
10mA
V
3.5
Linear-Regulator Output
Undervoltage Lockout
Threshold
BATTERY CHARGER
ISET Leakage Current
BBATT Leakage Current
Charge-Switch On Voltage
Charge-Switch Loss Current
LOW-BATTERY COMPARATOR
LBI Falling Trip Voltage
LBI Rising Trip Voltage
LBI Input Current
LBO,
FULL Output Leakage
Current
LBO,
FULL Output Voltage Low
LBI Comparator Response Time
V
UVLO
LRO rising hysteresis = 200mV
2.65
2.97
V
I
ISET(LEAK
)
V
ISET
= 28V, V
BBATT
= 0
-5
0.5
I
ISET
= 10mA, V
CCMD
= 0, V
BBATT
= 2V
CCMD
= GND, I
ISET
= 10mA, V
BBATT
= 2V,
%loss = [(I
ISET
- I
BBATT
) / I
ISET
)
·
100%
0.3
1
0.1
5
5
1.3
5
µA
µA
V
%
I
BBATT(LEAK
) V
ISET
= 0 or 28V, V
BBATT
= 6V
V
LBTL
V
LBTH
I
LBI
I
LBO,
I
FULL
V
LBI
= 1.9V
V
LBO
= V
FULL
= 5.5V
I
SINK
= 1mA
t
PD
Overdrive = 100mV
1.76
1.955
1.8
2
0.2
1.84
2.045
10
1
0.4
V
V
nA
µA
V
µs
20
2
_______________________________________________________________________________________
Bridge-Battery Backup Controllers
for Notebooks
ELECTRICAL CHARACTERISTICS (continued)
(V
LRI
= V
ISET
= 20V,
CCMD
=
DCMD
=
BBON
= LRO, V
BBATT
= 3V, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at
T
A
= +25°C.) (Note 1)
PARAMETER
DC-DC CONVERTER
FB Trip Point
FB Input Current
LX Switch Current Limit
LX Off-Leakage
LX On-Resistance
LX Zero Crossing Trip Threshold
BBON
Logic Input Low Voltage
TIMER BLOCK
CC Output Current
CD Oscillator Frequency
CC Oscillator Frequency
ISET Logic Input Low Voltage
CD to CC Current Matching
Logic Input Low Level
Logic Input High Level
Logic Input Leakage Current
V
CCMD
= 0, CC = GND
C
CD
= 3.3nF
C
CC
= 33nF
Resets the counter
V
DCMD
= 0, CD = GND
CCMD, DCMD
CCMD, DCMD
V
CCMD
, V
DCMD
= 0 to V
LRO
2.2
1
4.35
600
60
0.4
-1
5.00
758
75.8
R
DSON
V
FB
I
FB
I
PEAK
V
FB
= 2.1V
R
BBON
= 100kΩ to GND
V
LX
= 12V
I
LX
= 200mA
Voltage that allows a new cycle, defined as
(V
BBATT
- V
LX
) (see
DC-DC Converter
section)
-0.2
0.580
1.95
0.15
0.835
0.01
0.5
-0.1
2.05
10
1.100
10
1.5
0.2
2.1
5.65
950
95
1
0.8
V
nA
A
µA
Ω
V
V
µA
Hz
Hz
V
%
V
V
µA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNIT
MAX1612/MAX1613
CD
OSC
CC
OSC
V
IL
V
IH
I
(CCMD),
I
(DCMD)
Note 1:
Specifications from 0°C to -40°C are guaranteed by design, not production tested.
Typical Operating Characteristics
(Circuit of Figure 3, T
A
= +25°C, unless otherwise noted.)
DISCHARGE TIME
vs. OUTPUT CURRENT
MAX612-01
OSCILLATOR FREQUENCY
vs. CAPACITANCE
MAX1612-02
EFFICIENCY vs. OUTPUT CURRENT
(BBATT = 3.6V)
80
70
EFFICIENCY (%)
60
50
40
30
BBATT = 3.6V
R
BBON
= 240kΩ
NOTE: DC-DC
CONVERTER
SUPPLIES V
LRI
1µ
10µ
100µ
1m
10m
100m
1
MAX612-03
120
2 CELLS (SANYO N-50AAA)
DISCHARGE TIME (MINUTES)
100
80
V
OUT
= 5V
60
40
20
0
0
5
10
15
20
25
30
35
40
V
OUT
= 7V
100k
90
V
OUT
= 5V
V
OUT
= 7V
V
OUT
= 6V
OSCILLATOR FREQUENCY (Hz)
10k
1k
100
CC
CD
10
20
10
45
1
0.1
0
1
10
CAPACITANCE (nF)
100
1000
OUTPUT CURRENT (A)
OUTPUT CURRENT (mA)
_______________________________________________________________________________________
3
Bridge-Battery Backup Controllers
for Notebooks
MAX1612/MAX1613
Typical Operating Characteristics (continued)
(Circuit of Figure 3, T
A
= +25°C, unless otherwise noted.)
EFFICIENCY vs. OUTPUT CURRENT
(BBATT = 2.4V)
MAX612-04
EFFICIENCY vs. OUTPUT CURRENT
(BBATT = 6V)
MAX612-05
QUIESCENT CURRENT
vs. LRI VOLTAGE
MAX1612
QUIESCENT CURRENT (µA)
40
MAX1613
R
BBON
= 100kΩ TO GND
30
MAX1612
20
MAX1613
10
V
BBON
= V
LRO
MAX612-06
90
80
70
EFFICIENCY (%)
60
50
40
30
20
10
0
1µ
10µ
100µ
1m
10m
100m
1
OUTPUT CURRENT (A)
BBATT = 2.4V
R
BBON
= 240kΩ
NOTE: DC-DC
CONVERTER
SUPPLIES V
LRI
V
OUT
= 5V
V
OUT
= 7V
V
OUT
= 6V
90
80
70
EFFICIENCY (%)
60
50
40
30
20
10
0
1µ
10µ
BBATT = 3.6V
50
BBATT = 2.4V
V
OUT
= 6V
R
BBON
= 240kΩ
NOTE: DC-DC
CONVERTER
SUPPLIES V
LRI
100µ
1m
10m
100m
1
0
0
5
10
15
V
LRI
(V)
20
25
30
OUTPUT CURRENT (A)
PEAK CURRENT vs. BBON CURRENT
MAX612-07
BBATT LEAKAGE CURRENT
vs. BBATT INPUT VOLTAGE
MAX612-08
MAX1613
LRO VOLTAGE vs. LRI VOLTAGE
I
LOAD
= 5mA
3.33
MAX612-09
1200
1000
PEAK CURRENT (mA)
800
600
400
200
0
5
7
9
2.0
1.5
BBATT LEAKAGE CURRENT (µA)
1.0
0.5
0
-0.5
-1.0
3.35
V
LRO
(V)
3.31
3.29
3.27
-1.5
-2.0
3.25
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
0
5
10
15
V
LRI
(V)
20
25
30
BBATT INPUT VOLTAGE (V)
11 13 15 17 19 21 23 25
BBON CURRENT (µA)
MAX1613
LRO VOLTAGE vs. LOAD CURRENT
V
LRI
= 20V
3.34
3.32
V
LRO
(V)
3.30
3.28
3.26
3.24
3.22
3.20
0
2
4
6
8
10 12 14 16 18 20
LOAD CURRENT (mA)
100
120
MAX612-10
SWITCHING FREQUENCY vs. R
BBON
MAX612-11
3.36
350
SWITCHING FREQUENCY (kHz)
300
250
200
150
160
200
240
R
BBON
(kΩ)
280
320
360
4
_______________________________________________________________________________________
Bridge-Battery Backup Controllers
for Notebooks
Pin Description
PIN
1
2
3
4
NAME
ISET
BBATT
LX
LBO
FUNCTION
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.
Bridge-Battery Connection. Bridge-battery charger output.
Step-Up DC-DC Converter N-Channel MOSFET Drain. The maximum operating range is 12V.
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
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
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
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.
Open-Drain Bridge-Battery Full Indicator Output. When the internal timer reaches all 1sec, FULL
goes high impedance.
Feedback Input of Step-Up DC-DC Converter. Regulates to 2V. Connect feedback resistors to set
output voltage (Figure 2).
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.
Ground
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).
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).
Power Ground and Step-Up DC-DC Converter N-Channel MOSFET Source
5V (MAX1612) or 3.3V (MAX1613) Linear-Regulator Output. Bypass to GND with a 1µF capacitor.
Maximum external load current is 10mA.
Linear-Regulator Supply Input
MAX1612/MAX1613
5
BBON
6
DCMD
7
CCMD
8
9
10
11
12
FULL
FB
LBI
GND
CC
13
14
15
16
CD
PGND
LRO
LRI
_______________________________________________________________________________________
5
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