19-5826; Rev 4/11
DS2711/DS2712
Loose-Cell NiMH Chargers
GENERAL DESCRIPTION
PIN CONFIGURATION
The DS2711 and DS2712 are ideal for in-system or
stand-alone charging of 1 or 2 AA or AAA NiMH
“loose” cells. Temperature, voltage, and charge time
are monitored to provide proper fast-charging control
algorithms for nickel metal hydride (NiMH) batteries.
Battery tests are included to detect defective or
inappropriate cells such as alkaline primary batteries.
The DS2711/DS2712 support series and parallel
topologies, with independent monitoring and control of
each cell. Charging of NiCd chemistry cells is also
supported.
CC1
CC2
LED1
VSS
LED2
CSOUT
VN1
VN0
APPLICATIONS
16
2
15
3
14
4
13
5
12
6
11
7
10
8
9
VP2
VP1
THM2
THM1
VDD
TMR
CTST
DMSEL
SO (150 mils)
TSSOP (4.4mm)
Desktop/Stand-Alone Chargers (AAA/AA)
Digital Still Cameras
Music Players
1
PIN DESCRIPTION
Games
PIN
NAME
FUNCTION
FEATURES
1
2
3
CC1
CC2
LED1
Charge 1 or 2 NiMH Cells
4
VSS
Detect and Avoid Charging Alkaline Cells
Precharge Deeply Depleted Cells
Fast Charge NiMH with -∆V Termination
Linear Control (DS2711)
5
6
7
8
9
10
11
12
13
14
LED2
CSOUT
VN1
VN0
DMSEL
CTST
TMR
VDD
THM1
THM2
Switch-Mode Control (DS2712)
15
VP1
16
VP2
Cell 1 Charge-Control Output
Cell 2 Charge-Control Output
Cell 1 Status
Ground Reference and ChipSupply Return
Cell 2 Status, Mode-Select Input
Current-Sense Output
Current-Sense + Input
Current-Sense - Input
Display-Mode Select
Cell Test Threshold Set
Charge Timer Set
Chip-Supply Input (4.0V to 5.5V)
Cell 1 Thermistor Input
Cell 2 Thermistor Input
Cell 1 Positive-Terminal Sense
Input
Cell 2 Positive-Terminal Sense
Input
Toys
Sensitivity of 2mV (typ)
Monitor Voltage, Temperature, and Time for
Safety and Secondary Termination
Regulate Charge Current:
Drive pMOS or pnp-Type Pass Element or
Switch, or an Optocoupler
Compatible with Popular Optocouplers and
Integrated Primary-Side PWM Controllers
Small 16-Pin SO or TSSOP Packages
1 of 15
DS2711/DS2712: Loose-Cell NiMH Chargers
PARAMETER
Threshold Voltage,
Thermistor - Min
Threshold Voltage,
Thermistor - Max
Threshold Voltage,
Thermistor - Stop
Threshold Current, TMR
Pin Suspend
Presence Test Current,
VP1, VP2
SYMBOL
CONDITIONS
VTHM-MAX
(Notes 1, 4, 6)
VTHM-STOP
ITMR-SUS
IPTST
Parallel: VDD ≥ 4.0V,
Series: VDD ≥ 4.5V
Reverse Leakage
Current, VP1, VP2
ILKGR
VIREF
µA
15
µA
µA
VDD = 0V, VP1 = 1.5V,
VP2 = 3.0V
Current-Sense Reference
Voltage
0.5
2
(Notes 1, 4, 6)
0.30
MAX
10
(Notes 1, 4, 6)
TYP
VDD x
0.73
VDD x
0.33
VDD x
0.29
0.1
VTHM-MIN
MIN
UNITS
V
0.36
V
V
(Note 1, 4, 7)
Gain, Current-Sense
Error Amp
Gain, Current-Sense
Comparator
Propagation Time,
Current-Sense
Comparator
Hysteresis, CurrentSense Comparator
125
mV
-6%
+6%
%
1.5
Ω-1
GM
DS2711 (Note 8)
0.9
GM
DS2712 (Note 8)
10
tPDLY
DS2712, 2mV
over/underdrive
VHYS-COMP
DS2712
Ω-1
0.25
µs
22
24
26
mV
MIN
TYP
MAX
UNITS
ELECTRICAL CHARACTERISTICS: TIMING
(4.0V ≤ VDD ≤ 5.5V, TA = -20°C to +70°C, unless otherwise noted.)
PARAMETER
SYMBOL
Internal Timebase Period
tBASE
Internal Timebase
Accuracy
Duty Factor, Series Fast
Charge
Duty Factor, Series
Precharge/Top-Off
Duty Factor, Parallel Fast
Charge
Duty Factor, Parallel
Precharge/Top-Off
Duty Factor, Maintenance
Charge
CONDITIONS
0.96
-10
+10
CC1
0.125
CC1, CC2
0.0156
tCTST
tPCHG
0.484
CC1, CC2
Precharge Timeout
0.250
CC1, CC2
%
0.969
CC1
Cell Test Interval
s
31
34
Minutes
4
VCELL < VBAT-MIN
Seconds
Minutes
Fast-Charge Termination
Hold-Off Period
Fast-Charge Flat Voltage
Timeout
tFLAT
VCELL not increasing
16
Minutes
Charge Timer Period
tCTMR
RTMR = 100kΩ
2.5
Hours
tTHO
3 of 15
