MAX71_C_E .......................................................0°C to +70°C
MAX71_E_E .................................................... -40°C to +85°C
MAX71_MJE ................................................. -55°C to +125°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+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
(I
V+
= 10mA, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Refer to the
Typical Operating Circuit.
All measurements are with respect to
BATT-, not GND.)
PARAMETER
V+ Voltage
I
V+
(Note 1)
BATT+ Leakage
BATT+ Resistance with Power On
C1 Capacitance
C2 Capacitance
REF Voltage
Undervoltage Lockout
External VLIMIT Input Range
THI, TLO, TEMP Input Range
THI, TLO Offset Voltage (Note 2)
THI, TLO, TEMP, VLIMIT Input Bias Current
VLIMIT Accuracy
Internal Cell Voltage Limit
Fast-Charge VSENSE
PGM3 = V+
Trickle-Charge VSENSE
PGM3 = open
PGM3 = REF
PGM3 = BATT-
Voltage-Slope Sensitivity (Note 3)
Timer Accuracy
Battery-Voltage to Cell-Voltage
Divider Accuracy
DRV Sink Current
2
CONDITIONS
5mA < I
V+
< 20mA
V+ = 0V, BATT+ = 17V
PGM0 = PGM1 = BATT-, BATT+ = 30V
MIN
4.5
5
TYP
MAX
5.5
5
UNITS
V
mA
µA
kΩ
µF
nF
30
0.5
5
0mA < I
REF
< 1mA
Per cell
1.96
0.35
1.25
0
2.04
0.50
2.50
2
10
1
30
1.65
250
3.9
7.8
15.6
31.3
-2.5
0
1.7
275
7.0
12.0
20.0
38.0
V
V
V
V
mV
µA
mV
V
mV
0V < TEMP < 2V, TEMP voltage rising
1.2V < V
LIMIT
< 2.5V, 5mA < I
DRV
< 20mA,
PGM0 = PGM1 = V+
V
LIMIT
= V+
-10
-1
-30
1.6
225
1.5
4.5
12.0
26.0
mV
MAX713
MAX712
-15
-1.5
V
DRV
= 10V
30
mV/t
A
per cell
15
1.5
%
%
mA
Maxim Integrated
MAX712/MAX713
NiCd/NiMH Battery
Fast-Charge Controllers
ELECTRICAL CHARACTERISTICS (continued)
(I
V
+ = 10mA, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Refer to the
Typical Operating Circuit.
All measurements are with respect to
BATT-, not GND.)
PARAMETER
FASTCHG
Low Current
FASTCHG
High Current
A/D Input Range (Note 4)
CONDITIONS
V
FASTCHG
= 0.4V
V
FASTCHG
= 10V
Battery voltage ÷ number of cells programmed
1.4
MIN
2
10
1.9
TYP
MAX
UNITS
mA
µA
V
Note 1:
The MAX712/MAX713 are powered from the V+ pin. Since V+ shunt regulates to +5V, R1 must be small enough to allow at
least 5mA of current into the V+ pin.
Note 2:
Offset voltage of THI and TLO comparators referred to TEMP.
Note 3:
t
A
is the A/D sampling interval (Table 3).
Note 4:
This specification can be violated when attempting to charge more or fewer cells than the number programmed. To ensure
proper voltage-slope fast-charge termination, the (maximum battery voltage) ÷ (number of cells programmed) must fall
within the A/D input range.
Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
CURRENT-SENSE AMPLIFIER
FREQUENCY RESPONSE (with 15pF)
20
MAX712/13 toc01
CURRENT-SENSE AMPLIFIER
FREQUENCY RESPONSE (with 10nF)
40
20
MAX712/13 toc02
40
C2 = 15pF
FASTCHG = 0V
10
GAIN (dB)
A
V
0
Φ
-40
0
PHASE (DEGREES)
GAIN (dB)
10
C2 = 10nF
FASTCHG = 0V
0
A
V
0
Φ
-10
-80
-40
PHASE (DEGREES)
35
30
25
20
15
10
5
0
0
10
20
30
40
50
60
BATTERY TEMPERATURE(°C)
BATTERY THERMISTOR RESISTANCE (kΩ)
BATT-
-10
CC
CURRENT-
SENSE
AMP
BATT-
+
+
-80
V
IN
-
V
OUT
-
GND
-20
1k
10k
100k
FREQUENCY (Hz)
1M
10M
-120
-20
10
100
1k
10k
FREQUENCY (Hz)
-120
CURRENT ERROR-AMPLIFIER
TRANSCONDUCTANCE
FASTCHG = 0V, V+ = 5V
DRV PIN SINK CURRENT(mA)
MAX712/13 toc03
SHUNT-REGULATOR VOLTAGE
vs. CURRENT
5.6
5.4
V+ VOLTAGE (V)
5.2
5.0
4.8
4.6
4.4
4.2
0.4
0.2
0
10
20
30
40
50
60
CURRENT INTO V+ PIN (mA)
DRV SINKING CURRENT
DRV NOT SINKING CURRENT
MAX712/13 toc04
ALPHA SENSORS PART No. 14A1002
STEINHART-HART INTERPOLATION
1.6
1.4
TEMP PIN VOLTAGE (V)
1.2
1.0
0.8
0.6
MAX712/13 toc05
100
5.8
10
1
0.1
1.95
4.0
1.97
1.99
2.01
2.03
2.05
VOLTAGE ON CC PIN (V)
Maxim Integrated
3
MAX712/MAX713
NiCd/NiMH Battery
Fast-Charge Controllers
Typical Operating Characteristics (continued)
(T
A
= +25°C, unless otherwise noted.)
MAX713
NiCd BATTERY CHARGING
CHARACTERISTICS AT C RATE
MAX712/13 toc06
MAX713
NiMH BATTERY CHARGING
CHARACTERISTICS AT C RATE
MAX712/13 toc07
CELL TEMPERATURE (°C)
1.55
CELL VOLTAGE (V)
ΔV
CUTOFF
Δt
T
40
1.50
V
35
1.55
V
ΔV
CUTOFF
Δt
35
1.45
30
1.50
T
1.45
30
1.40
25
25
0
30
60
90
0
30
60
90
CHARGE TIME (MINUTES)
CHARGE TIME (MINUTES)
MAX713
NiCd BATTERY-CHARGING
CHARACTERISTICS AT C/2 RATE
MAX712/13 toc08
MAX713
NiMH BATTERY CHARGING
CHARACTERISTICS AT C/2 RATE
MAX712/13 toc09
CELL TEMPERATURE (°C)
1.50
V
1.45
1.40
T
35
1.45
V
30
30
25
T
1.40
25
0
50
100
150
0
CHARGE TIME (MINUTES)
100
50
150
CHARGE TIME (MINUTES)
MAX713
CHARGING CHARACTERISTICS OF A
FULLY-CHARGED NiMH BATTERY
1.65
V
1.60
CELL VOLTAGE (V)
ΔV
CUTOFF
Δt
1.55
35
MAX712/13 toc10
MAX713
CHARGING CHARACTERISTICS OF A
FULLY CHARGED NiMH BATTERY
1.65
40
CELL TEMPERATURE (°C)
CELL VOLTAGE (V)
MAX712/13 toc11
5 MINUTE REST
BETWEEN CHARGES
1.60
V
1.55
5-HOUR REST
BETWEEN CHARGES
1.50
T
1.45
35
1.50
T
30
25
30
1.45
25
0
5
10
15
20
0
CHARGE TIME (MINUTES)
5
10
15
CHARGE TIME (MINUTES)
20
4
CELL TEMPERATURE (°C)
ΔV
CUTOFF
Δt
40
CELL TEMPERATURE (°C)
1.50
CELL VOLTAGE (V)
CELL VOLTAGE (V)
ΔV
CUTOFF
Δt
1.55
35
ΔV
CUTOFF
Δt
40
CELL TEMPERATURE (°C)
1.60
CELL VOLTAGE (V)
40
Maxim Integrated
MAX712/MAX713
NiCd/NiMH Battery
Fast-Charge Controllers
Pin Description
PIN
1
2
NAME
VLIMIT
BATT+
FUNCTION
Sets the maximum cell voltage. The battery terminal voltage (BATT+ - BATT-) will not exceed VLIMIT x
(number of cells). Do not allow VLIMIT to exceed 2.5V. Connect VLIMIT to VREF for normal operation.
Alternatively, connect VLIMIT to V+ to set the maximum cell voltage to an internally preset 1.65V/cell.
Positive terminal of battery
PGM0 and PGM1 set the number of series cells to be charged. The number of cells can be set from
1 to 16 by connecting PGM0 and PGM1 to any of V+, REF, or BATT-, or by leaving the pin unconnected
(Table 2). For cell counts greater than 11, see the
Linear-Mode, High Series Cell Count
section.
Charging more or fewer cells than the number programmed may inhibit
ΔV
fast-charge termination.
Trip point for the over-temperature comparator. If the voltage-on TEMP rises above THI, fast charge ends.
Trip point for the under-temperature comparator. If the MAX712/MAX713 power on with the voltage-
on TEMP less than TLO, fast charge is inhibited and will not start until TEMP rises above TLO.
Sense input for temperature-dependent voltage from thermistors.
Open-drain, fast-charge status output. While the MAX712/MAX713 fast charge the battery,
FASTCHG
sinks current. When charge ends and trickle charge begins,
FASTCHG
stops sinking current.
PGM2 and PGM3 set the maximum time allowed for fast charging. Timeouts from 33 minutes to 264
minutes can be set by connecting to any of V+, REF, or BATT-, or by leaving the pin unconnected
(Table 3). PGM3 also sets the fast-charge to trickle-charge current ratio (Table 5).
Compensation input for constant current regulation loop
Negative terminal of battery
System ground. The resistor placed between BATT- and GND monitors the current into the battery.
Current sink for driving the external PNP current source
Shunt regulator. The voltage on V+ is regulated to +5V with respect to BATT-, and the shunt current
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