Datasheet

MAX712/MAX713
NiCd/NiMH Battery
Fast-Charge Controllers
3
Maxim Integrated
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.)
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.
Battery voltage ÷ number of cells programmed
V
FASTCHG
= 10V
V
FASTCHG
= 0.4V
CONDITIONS
V1.4 1.9A/D Input Range (Note 4)
µA10
FASTCHG High Current
mA2
FASTCHG Low Current
UNITSMIN TYP MAXPARAMETER
Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
20
1k
100k
1M10k 10M
CURRENT-SENSE AMPLIFIER
FREQUENCY RESPONSE (with 15pF)
-20
FREQUENCY (Hz)
GAIN (dB)
PHASE (DEGREES)
-10
0
10
40
-120
-80
-40
0
C2 = 15pF
FASTCHG = 0V
V
OUT
V
IN
CURRENT-
SENSE
AMP
BATT-
BATT-
CC
GND
-
-
+
+
A
V
Φ
MAX712/13 toc01
20
-10
-20
10 1k
CURRENT-SENSE AMPLIFIER
FREQUENCY RESPONSE (with 10nF)
0
10
40
-80
-120
-40
0
FREQUENCY (Hz)
GAIN (dB)
PHASE (DEGREES)
100 10k
C2 = 10nF
FASTCHG = 0V
A
V
Φ
MAX712/13 toc02
100
0.1
1.95 1.97 2.01 2.05
CURRENT ERROR-AMPLIFIER
TRANSCONDUCTANCE
1
10
VOLTAGE ON CC PIN (V)
DRV PIN SINK CURRENT(mA)
1.99 2.03
FASTCHG = 0V, V+ = 5V
MAX712/13 toc03
5.8
4.8
060
SHUNT-REGULATOR VOLTAGE
vs. CURRENT
5.6
CURRENT INTO V+ PIN (mA)
V+ VOLTAGE (V)
30
5.2
5.0
10 20 50
5.4
4.0
4.4
4.2
4.6
40
DRV NOT SINKING CURRENT
DRV SINKING CURRENT
MAX712/13 toc04
1.0
060
ALPHA SENSORS PART No. 14A1002
STEINHART-HART INTERPOLATION
1.6
BATTERY TEMPERATURE(°C)
TEMP PIN VOLTAGE (V)
BATTERY THERMISTOR RESISTANCE (kΩ)
30
1.4
1.2
10 20 50
0.2
0.6
0.4
0.8
20
35
30
25
0
10
5
15
40
MAX712/13 toc05