AVAILAB
LE
NiMH Battery Pack Charge Controller
www.maxim-ic.com
DS2715
DESCRIPTION
The DS2715 is well suited for cost-sensitive charger
applications where the battery pack is either internal
or external to the application. It has been optimized for
safe and reliable charging of 1 to 10 NiMH cells in
series. The internal gain block can be selected as
either a comparator or transconductance amplifier for
charge current regulation. This makes the DS2715
configurable as a switched DC charger, a linear
current regulator, or a switchmode current source.
The DS2715 pre-conditions severely depleted cells
before entering full charge mode. It terminates full
charge using the dT/dt technique, which requires an
external sensing thermistor. Over-temperature, under-
temperature, and over-voltage detection prevents
charging under unsafe conditions. A user selectable
charge timer allows charge rates from 0.167C to 2C.
FAST-CHARGE, TOPOFF and DONE modes are
included for highly reliable, safe charging of NiMH
cells. Discharge mode allows the DS2715 to enter a
low power sleep state while the cell pack is being
discharged.
PIN CONFIGURATION
C
BIAS
V
CH
V
SS
LED1
DNC
V
SS
CTG
CTG
V
BATT
THM
R
T
V
DD
SNS-
SNS+
DIV
MODE
See Table 1 for Ordering Information.
16 SO
Table 1. ORDERING INFORMATION
PART
DS2715Z+
DS2715Z+T&R
DS2715BZ+
DS2715BZ+T&R
MARKING
D2715
D2715
D2715B
D2715B
PIN-PACKAGE
16 SO
16 SO
16 SO
16 SO
FEATURES
Charges 1 to 10 NiMH Cells
FAST-CHARGE at up to a 2C Rate
PRECHARGE and TOPOFF Charge Modes Help
Cell Conditioning
Functional Diagrams
Load Detection Allows the DS2715 to Enter Low
Power Sleep Mode (Less than 10µA) while the
Cell Pack is Discharged
dT/dt Charge Termination Eliminates Cell Charge
Stress
Monitors Voltage, Temperature, and Time for
Safety and Secondary Termination
Regulates Current through Either Linear Control
or Switch-Mode Control
LED Output Displays Charge State
Small 16-Pin SO Package
+ Denotes a lead(Pb)-free/RoHS-compliant package.
T&R = Tape and reel.
OPERATIONAL DIAGRAM
APPLICATIONS
Portable DVD Players
Portable Television Sets
Handheld Gaming
Test Equipment
Pin Configurations appear at end of data sheet.
Handheld POS Terminals
Functional Diagrams continued at end of data sheet.
UCSP is a trademark of Maxim Integrated Products, Inc.
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
19-4592; 4/09
DS2715: NiMH Battery Pack Charge Controller
ABSOLUTE MAXIMUM RATINGS*
Voltage on V
DD
and V
CH
Pins with Respect to V
SS
Voltage on LED1 Pin
Voltage on SNS-
Voltage on C
BIAS
Voltage on all Other Pins
Continuous Sink Current V
CH
and LED1
Operating Temperature Range
Storage Temperature Range
Soldering Temperature
Human Body Model (HBM) ESD Limit of V
CH
Pin
HBM ESD Limit of all Other Pins
-0.3V to +18V
-0.3V to +18V
-0.3V to +0.3V
-0.3V to 6V
-0.3V to V
Cbias
28mA
-20°C to +85°C
-55°C to +125°C
See IPC/JEDEC J-STD-020
500V
2KV
*This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operation
sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability.
RECOMMENDED DC OPERATING CONDITIONS
PARAMETER
Supply Voltage
LED1 Voltage
Mode Voltage
V
CH
Voltage
C
BIAS
Capacitor Range
R
T
Resistor Range
SYMBOL
V
DD
V
LED
V
MODE
V
VCH
C
Cbias
R
Rt
CONDITIONS
(Note 1)
(Note 1)
(Note 1)
(Note 1)
(4.5V
V
DD
16.5V; T
A
= 0C to +70C.)
MIN
TYP
MAX
UNITS
4.5
16.5
V
0.0
0.0
0.0
.02
20
16.5
V
Cbias
16.5
.15
240
V
V
V
μF
KΩ
DC ELECTRICAL CHARACTERISTICS
PARAMETER
Operating Current
(Note 2)
Idle Current
Discharge Current
UVLO Threshold
UVLO Hysteresis
V
CH
Sink Current
LED1 Sink Current
Leakage Current, V
CH
,
LED1
THM Pin Leakage
Current
V
BATT
Pin Leakage
Current
C
BIAS
Voltage
DIV Pin Load Current
Current Sense Amplifier
Gain
SYMBOL
I
DDA
I
DDS
I
DDD
V
UVLO
V
UVLO-HYS
I
OL-Vch
I
OL-LED
I
LKG
I
LKG-THM
I
LKG-Vbatt
V
Cbias
I
Div
G
ERR
(4.5V
V
DD
16.5V, T
A
= 0C to +70C, unless otherwise noted.)
CONDITIONS
MIN
TYP
MAX
UNITS
1.3
150
1.6
250
10
200
3.8
20
20
-1
-1
-50
+1
+1
+50
4.0
4.3
500
3.9
35
4.0
mA
μA
μA
μA
V
mV
mA
mA
μA
μA
nA
V
uA
Ω
-1
Linear Mode, V
DD
= 16.5V
Comparator Mode,
V
DD
= 16.5V
V
DD
< V
UVLO
Discharge latch set (Note 2)
V
DD
Rising (Note 3)
V
DD
Falling
V
OL
= 1.5V
V
OL
= 1.0V
Pin Inactive or Device Idle
0 < I
Cbias
< 0.4mA
3.9
100μA < I
Vch
< 20mA
5
6.25
7.5
DS2715: NiMH Battery Pack Charge Controller
PARAMETER
Current Sense
Comparator Gain
SYMBOL
G
COMP
CONDITIONS
(Note 7)
MIN
10
TYP
MAX
UNITS
Ω
-1
AC ELECTRICAL CHARACTERISTICS
PARAMETER
UVLO Debounce Time
Current Sense
Comparator Propagation
Delay
Discharge Detect
Propagation Delay
Return To Normal
Function (Op-Amp or
Comparator Mode)
R
T
Timing Accuracy
Internal Clock Accuracy
SYMBOL
t
UVLO
t
COMP
t
DD
t
RNF
t
Rt
t
BASE
(Note 7)
(4.5V
V
DD
16.5V, T
A
= 0C to +70C, unless otherwise noted.)
CONDITIONS
MIN
TYP
MAX
UNITS
10
250
1
1
-10
-10
+10
+10
μs
ns
μs
μs
%
%
From detection of current
reversal
Time from reset of discharge
latch
(Note 4)
ELECTRICAL CHARACTERISTICS: CHARGING
PARAMETER
FAST-CHARGE
Comparator Threshold
FAST-CHARGE
Comparator Hysteresis
TOPOFF and
PRECHARGE
Comparator Threshold
TOPOFF and
PRECHARGE
Comparator Hysteresis
Discharge Latch Reset
Threshold
Discharge Latch Set
Threshold
Low Battery Detect
Threshold
Cell Detect Threshold
No Cell Detect Threshold
Presence Detect
Threshold Hysteresis
Minimum Charge Temp
Maximum Charge Temp
Over Temp
dT/dt Detect
SYMBOL
V
FC
V
HYS-FC
V
TO
V
HYS-TO
V
DCHG-RST
V
DCHG-SET
V
LB
V
DET
V
OPEN
V
HYS-PD
V
THM-MIN
V
THM-MAX
V
THM-STOP
T
TERM
(Note 5, 6)
(Note 5, 6)
(Note 5, 6)
Reverse current through
sense resistor
From presence detect into
PRECHARGE
FAST-CHARGE
FAST-CHARGE
(4.5V
V
DD
16.5V, T
A
= 0C to +70C, unless otherwise noted.)
CONDITIONS
MIN
TYP
MAX
UNITS
-127
31
-38
10
-15
5
0.95
1.50
1.60
90
2.88
1.28
1.12
0.425
-121
28
-33
8
-10
10
1.0
1.55
1.65
100
2.92
0
1.32
45
1.16
50
0.5
-115
25
-28
6
-5
15
1.05
1.60
1.70
110
2.96
1.36
1.20
0.575
mV
mV
mV
mV
mV
mV
V
V
V
mV
V
ºC
V
ºC
V
ºC
ºC/min
TOPOFF and PRECHARGE
TOPOFF and PRECHARGE
DS2715: NiMH Battery Pack Charge Controller
PARAMETER
dT/dt Blanking Time
PRECHARGE Timeout
FAST-CHARGE Timer
Range
TOPOFF to FAST-
CHARGE Duration Ratio
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
Note 7:
SYMBOL
t
BLANK
t
PC-TO
t
FC
CONDITIONS
MIN
3.85
TYP
4.3
30
MAX
4.75
UNITS
Min
Min
0.5
DS2715
DS2715B
1:2
1:4
6
Hours
Voltages relative to V
SS
.
Does not include current through V
CH
, R
T
, and DIV pins.
Below this voltage no I/O pins are active.
Does not include tolerance of R
T
resistor.
V
BIAS
and resistor tolerances must be added to determine actual threshold.
Specified temperature thresholds are only valid if recommended thermistor types are used.
Specification is guaranteed by design.
DETAILED PIN DESCRIPTION
PIN
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
NAME
C
BIAS
V
CH
V
SS
LED1
DNC
V
SS
CTG
CTG
MODE
DIV
SNS+
SNS-
V
DD
R
T
THM
V
BATT
DESCRIPTION
Bypass for Internal Voltage Regulator
Cell Stack Charge Control Output
Chip Supply Return and Local Ground Reference
Charging Indicator Output
Do Not Connect
Chip Supply Return and Local Ground Reference
Connect to Local Ground (V
SS
)
Connect to Local Ground (V
SS
)
Mode Select. Connect to V
SS
for linear mode of operation or C
BIAS
for comparator
mode of operation.
Thermistor Divider. Stable output to form a resistor divider for measuring
temperature on THM
Positive Current Sense. Connect to the charge source side of the sense resistor
Negative Current Sense. Connect to the cell stack side of the sense resistor
Chip Supply Input: +4.5V to +16.5V range
Failsafe Timeout. Timeout is selected by an external resistor from R
T
to V
SS
Thermistor Input. Connect to a thermistor located in the cell pack and a divider
resistor from the Div pin
Battery Voltage Sense Input. Connect to a divider from the positive terminal of the
cell stack to measure the voltage of a single cell
DS2715: NiMH Battery Pack Charge Controller
Figure 1. BLOCK DIAGRAM
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