MAX712CPE Maxim Integrated Products, MAX712CPE Datasheet - Page 9

• Manufacturer Part Number: MAX712CPE
• Description: IC BATT FASTCHRG NICD/NIMH 16DIP
• Manufacturer: Maxim Integrated Products

Specifications of MAX712CPE

• Function: Charge Management
• Battery Type: Nickel Cadmium (NiCd), Nickel Metal-Hydride (NiMH)
• Voltage - Supply: 4.5 V ~ 5.5 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Through Hole
• Package / Case: 16-DIP (0.300", 7.62mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

The MAX712/MAX713 can be configured so that voltage
slope and/or battery temperature detects full charge.
Figure 4 shows a charging event in which a battery is
inserted into an already powered-up MAX712/MAX713.
During time 1, the charger’s output voltage is regulated
at the number of cells times VLIMIT. Upon insertion of
the battery (time 2), the MAX712/MAX713 detect cur-
rent flow into the battery and switch to fast-charge
state. Once full charge is detected, the device reverts
to trickle charge (time 3). If the battery is removed (time
4), the MAX712/MAX713 remain in trickle charge and
the output voltage is once again regulated as in time 1.
AC-to-DC wall-cube adapters typically consist of a trans-
former, a full-wave bridge rectifier, and a capacitor.
Figures 10–12 show the characteristics of three con-
sumer product wall cubes. All three exhibit substantial
120Hz output voltage ripple. When choosing an adapter
for use with the MAX712/MAX713, make sure the lowest
wall-cube voltage level during fast charge and full load is
at least 1.5V higher than the maximum battery voltage
while being fast charged. Typically, the voltage on the
Table 4. MAX712/MAX713 Charge-State Transition Table
*** Batteries that are too hot when inserted (or when circuit is powered up) will not enter fast charge until they cool and power is recycled.
** If the battery is cold at power-up, the first rising edge on COLD will trigger fast charge; however, a second rising edge will
† Only two states exist: fast charge and trickle charge.
P P O O W W E E R R _ _ O O N N _ _ R R E E S S E E T T
* Regardless of the status of the other logic lines, a timeout or a voltage-slope detection will set trickle charge.
have no effect.
0
↑
↑
↑
↑
↑
1
1
1
1
1
1
1
1
1
1
1
Powering the MAX712/MAX713
_______________________________________________________________________________________
UNDER_VOLTAGE
↓
↑
x
1
x
x
x
0
0
0
0
0
0
x
x
0
x
I I N N _ _ R R E E G G U U L L A A T T I I O O N N
1
0
0
0
0
↓
0
0
0
↑
x
x
x
x
x
x
x
Fast-Charge Controllers
battery pack is higher during a fast-charge cycle than
while in trickle charge or while supplying a load. The volt-
age across some battery packs may approach 1.9V/cell.
The 1.5V of overhead is needed to allow for worst-case
voltage drops across the pass transistor (Q1 of Typical
Figure 5. DRV Pin Cascode Connection (for high DC IN voltage
or to reduce MAX712/MAX713 power dissipation in linear mode)
C C O O L L D D
x
x
x
0
x
1
1
↓
1
1
1
↑
0
x
x
x
x
DC IN
NiCd/NiMH Battery
†
H H O O T T
R1
↑
↓
x
x
x
x
0
1
1
1
1
1
1
x
0
x
x
V+
R2
MAX712
MAX713
Set trickle
No change
No change
No change
No change***
Set fast
No change
No change
Set fast
Set fast
No change***
Set fast**
Trickle to fast transition inhibited
Trickle to fast transition inhibited
Set trickle
Set trickle
Set trickle
DRV
Q1
2N3904
RESULT*
D1
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