MAXIM DS2715 Technical data
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NiMH Battery Pack Charge Controlle
DS2715
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www.maxim-ic.com
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, undertemperature, and over-voltage detection prevents
charging under unsafe conditions. A user selectable
charge timer allows charge rates from 0.167°C to 2°C.
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.
FEATURES
Charges 1 to 10 NiMH Cells
FAST-CHARGE at up to a 2C Rate
PRECHARGE and TOPOFF Charge Modes Help
Cell Conditioning
Load Detection Allows the DS2715 to Enter Low
Power Sleep Mode (Less than 10µA) while the
Cell Pack is Discharged
PIN CONFIGURATION
C
LED1
DNC
CTG
CTG
See Table 1 for Ordering Information.
Table 1.
PART MARKING PIN-PACKAGE
DS2715Z+
DS2715Z+T&R DS2715+ 16 SO
+ Denotes a lead-free package.
T&R = tape and reel
OPERATIONAL DIAGRAM
BIAS
V
V
V
CH
SS
SS
V
BATT
THM
R
T
V
DD
SNS-
SNS+
DIV
MODE
16 SO
ORDERING INFORMATION
DS2715+
16 SO
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
APPLICATIONS
Portable DVD Players
Portable Television Sets
Handheld Gaming
Test Equipment
Handheld POS Terminals
Note: Some revisions of this device may incorporate deviations from published specifications known as errata. Multiple revisions of any device
may be simultaneously available through various sales channels. For information about device errata, click here: www.maxim-ic.com/errata.
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DS2715: NiMH Battery Pack Charge Controller
ABSOLUTE MAXIMUM RATINGS*
Voltage on VDD and VCH Pins with Respect to VSS -0.3V to +18V
Voltage on LED1 Pin -0.3V to +18V
Voltage on SNS- -0.3V to +0.3V
Voltage on C
Voltage on all Other Pins -0.3V to V
-0.3V to 6V
BIAS
Cbias
Continuous Sink Current VCH and LED1 28mA
Operating Temperature Range -20°C to +85°C
Storage Temperature Range -55°C to +125°C
Soldering Temperature See IPC/JEDEC J-STD-020
Human Body Model (HBM) ESD Limit of V
HBM ESD Limit of all Other Pins 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.
Pin 500V
CH
RECOMMENDED DC OPERATING CONDITIONS
(4.5V ≤ VDD ≤ 16.5V; T
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Supply Voltage V
LED1 Voltage V
Mode Voltage V
VCH Voltage V
DD
LED
MODE
VCH
(Note 1) 4.5 16.5 V
(Note 1) 0.0 16.5 V
(Note 1) 0.0 V
(Note 1) 0.0 16.5 V
= 0°C to +70°C.)
A
Cbias
V
C
Capacitor Range C
BIAS
RT Resistor Range R
Cbias
Rt
.02 .15 μF
20 240 KΩ
DC ELECTRICAL CHARACTERISTICS
(4.5V ≤ VDD ≤ 16.5V, T
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Operating Current
(Note 2)
Idle Current I
Discharge Current I
UVLO Threshold V
UVLO Hysteresis V
VCH Sink Current I
LED1 Sink Current I
Leakage Current, VCH,
LED1
THM Pin Leakage
Current
V
Pin Leakage
BATT
Current
I
I
I
DDA
DDS
DDD
UVLO
UVLO-HYS
OL-Vch
OL-LED
I
LKG
LKG-THM
LKG-Vbatt
Linear Mode, V
Comparator Mode,
= 16.5V
V
DD
VDD < V
UVLO
Discharge latch set (Note 2) 200 μA
VDD Rising (Note 3) 3.8 3.9 4.0 V
VDD Falling 35 mV
VOL = 1.5V 20 mA
VOL = 1.0V 20 mA
Pin Inactive or Device Idle -1 +1 μA
-1 +1 μA
-50 +50 nA
= 16.5V 1.3 1.6 mA
DD
= 0°C to +70°C, unless otherwise noted.)
A
150 250 μA
10 μA
C
Voltage V
BIAS
DIV Pin Load Current I
Current Sense Amplifier
Gain
G
Cbias
Div
ERR
0 < I
< 0.4mA 3.9 4.0 4.3 V
Cbias
500 uA
100μA < I
< 20mA 5 6.25 7.5 Ω
Vch
-1
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DS2715: NiMH Battery Pack Charge Controller
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Current Sense
Comparator Gain
G
COMP
(Note 7) 10 Ω
-1
AC ELECTRICAL CHARACTERISTICS
(4.5V ≤ VDD ≤ 16.5V, T
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
= 0°C to +70°C, unless otherwise noted.)
A
UVLO Debounce Time t
UVLO
10 μs
Current Sense
Comparator Propagation
t
COMP
(Note 7) 250 ns
Delay
Discharge Detect
Propagation Delay
Return To Normal
Function (Op-Amp or
Comparator Mode)
RT Timing Accuracy t
Internal Clock Accuracy t
t
DD
t
RNF
Rt
BASE
From detection of current
reversal
Time from reset of discharge
latch
1 μs
1 μs
(Note 4) -10 +10 %
-10 +10 %
ELECTRICAL CHARACTERISTICS: CHARGING
(4.5V ≤ VDD ≤ 16.5V, T
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
FAST-CHARGE
Comparator Threshold
FAST-CHARGE
Comparator Hysteresis
V
V
HYS-FC
FC
FAST-CHARGE -127 -121 -115 mV
FAST-CHARGE 31 28 25 mV
TOPOFF and
PRECHARGE
V
TO
TOPOFF and PRECHARGE -38 -33 -28 mV
Comparator Threshold
TOPOFF and
PRECHARGE
V
HYS-TO
TOPOFF and PRECHARGE 10 8 6 mV
Comparator Hysteresis
Discharge Latch Reset
Threshold
Discharge Latch Set
Threshold
Low Battery Detect
Threshold
V
DCHG-RST
V
DCHG-SET
V
-15 -10 -5 mV
Reverse current through
sense resistor
LB
From presence detect into
PRECHARGE
= 0°C to +70°C, unless otherwise noted.)
A
5 10 15 mV
0.95 1.0 1.05 V
Cell Detect Threshold V
No Cell Detect Threshold V
Presence Detect
Threshold Hysteresis
V
Minimum Charge Temp V
Maximum Charge Temp V
Over Temp V
THM-MAX
THM-STOP
dT/dt Detect T
DET
OPEN
HYS-PD
THM-MIN
TERM
1.50 1.55 1.60 V
1.60 1.65 1.70 V
90 100 110 mV
(Note 5, 6)
(Note 5, 6)
(Note 5, 6)
0.425 0.5 0.575 ºC/min
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2.88 2.92 2.96 V
0 ºC
1.28 1.32 1.36 V
45 ºC
1.12 1.16 1.20 V
50 ºC
DS2715: NiMH Battery Pack Charge Controller
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
dT/dt Blanking Time t
BLANK
3.85 4.3 4.75 Min
PRECHARGE Timeout t
FAST-CHARGE Timer
Range
TOPOFF to FASTCHARGE Duration Ratio
Note 1: Voltages relative to V Note 2: Does not include current through V Note 3: Below this voltage no I/O pins are active. Note 4: Does not include tolerance of R Note 5: V Note 6: Specified temperature thresholds are only valid if recommended thermistor types are used. Note 7: Specification is guaranteed by design.
and resistor tolerances must be added to determine actual threshold.
BIAS
PC-TO
t
FC
1:2
.
SS
30 Min
0.5 6 Hours
, RT, and DIV pins.
CH
resistor.
T
DETAILED PIN DESCRIPTION
PIN NAME DESCRIPTION
1 C
2 V
3 V
BIAS
CH
SS
4 LED1 Charging Indicator Output
5 DNC Do Not Connect
6 V
SS
7 CTG Connect to Local Ground (VSS)
8 CTG Connect to Local Ground (VSS)
9 MODE
10 DIV
11 SNS+ Positive Current Sense. Connect to the charge source side of the sense resistor
12 SNS- Negative Current Sense. Connect to the cell stack side of the sense resistor
13 V
14 R
DD
T
15 THM
16 V
BATT
Bypass for Internal Voltage Regulator
Cell Stack Charge Control Output
Chip Supply Return and Local Ground Reference
Chip Supply Return and Local Ground Reference
Mode Select. Connect to V
for linear mode of operation or C
SS
for comparator
BIAS
mode of operation.
Thermistor Divider. Stable output to form a resistor divider for measuring
temperature on THM
Chip Supply Input: +4.5V to +16.5V range
Failsafe Timeout. Timeout is selected by an external resistor from RT to V
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
SS
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Figure 1. BLOCK DIAGRAM
DS2715: NiMH Battery Pack Charge Controller
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