DS2714
Quad Loose Cell NiMH Charger
www.maxim-ic.com
GENERAL DESCRIPTION
The DS2714 is ideal for standalone charging of 1 to 4
AA or AAA NiMH “loose” cells. NiCd cells can also be
charged. 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 DS2714 supports a parallel charging topology,
with independent monitoring and control of each cell.
FEATURES
Charges 1 to 4 NiMH Cells
Detects and Avoids Charging Alkaline Cells
Pre-Charges Deeply Depleted Cells
Fast Charges NiMH with -ΔV Termination
Sensitivity of 2mV (typ)
Monitors Voltage, Temperature and Time for
Safety and Secondary Termination
Works with Regulated Charge Current Source
Drives PNP Type Pass Element
Compatible with Integrated Primary-Side PWM
Controllers
20-pin TSSOP Package
APPLICATIONS
Desktop/Standalone Chargers (AAA/AA)
Digital Still Cameras
Music Players
Games
Toys
ORDERING INFORMATION
PART
DS2714E+
DS2714E+T&R
MARKING
DS2714
DS2714
PIN-PACKAGE
20 TSSOP
20 TSSOP Tape-and-Reel
+Denotes lead-free package.
CHARGE TOPOLOGY
4-Cell NiMH Charger
Controlled
Current
Source
PIN CONFIGURATION
DS2714
GND
TSSOP
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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REV: 080206
DS2714:
Quad Loose Cell NiMH Charger
ABSOLUTE MAXIMUM RATINGS
Voltage Range on Any Pin Relative to V
SS
Voltage on DMSEL
Continuous Sink Current CC1-4, LED1-4
Operating Temperature Range
Storage Temperature Range
Soldering Temperature
-0.3V to +6V
V
DD
+ 0.3V
20mA
-40°C to +85°C
-55°C to +125°C
See IPC/JEDECJ-STD-020A
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only,
and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is
not implied. Exposure to the absolute maximum rating conditions for extended periods may affect device reliability.
RECOMMENDED DC OPERATING CONDITIONS
(4.0V
≤
V
DD
≤
5.5V; T
A
= -20°C to +70°C)
PARAMETER
Supply Voltage
Input Voltage Range
SYMBOL
V
DD
CONDITIONS
(Note 1)
LEDx, DMSEL
MIN
4.0
-0.3
TYP
MAX
5.5
5.5
UNITS
V
V
DC ELECTRICAL CHARACTERISTICS
PARAMETER
Supply Current, V
DD
Output Voltage Low, CC1-4.
LED1-4
Leakage Current,
CC1-4 LED1-4
Threshold Voltage,
-ΔV Termination
Mode Test Current, DMSEL
Input Logic High, DMSEL,
Input Logic Low, DMSEL,
Input Leakage Current,
DMSEL
Threshold Voltage, Cell Test
Accuracy
Threshold Voltage, Cell Test
Range
Threshold Voltage, Cell
Voltage Low
Threshold Voltage, Cell
Voltage Max1
Threshold Voltage, Cell
Voltage Max2
Threshold Voltage, Thermistor
- Min
Threshold Voltage, Thermistor
- Max
Threshold Voltage, Thermistor
- Stop
Threshold Current, TMR Pin
Suspend
SYMBOL
I
DD
V
OL1
I
LKG
V
-ΔV
I
MTST
V
IH
V
IL
I
IL1
V
CTST-ACC
V
CTST-RANGE
V
BAT-LOW
V
BAT-MAX1
V
BAT-MAX2
V
THM-MIN
V
THM-MAX
V
THM-STOP
I
TMR-SUS
(4.0V
≤
V
DD
≤
5.5V; T
A
= -20°C to +70°C. Unless otherwise noted.)
CONDITIONS
Operating mode
VDD = 5.0V,
I
OL
= 20mA (Note 1)
VDD = 5.0V,
Output inactive
After t
THO
Pulse high/low once
<5ms after power-up
(Note 1)
(Note 1)
After power-up mode
select,
DMSEL = V
DD
or V
SS
R
TMR
= 80KΩ
MIN
TYP
500
MAX
750
1.0
-1
1.0
-
V
DD
-
0.2V
0.2
-1
-15
32
CC1 = CC2 = hi-Z
(Note 1, 2)
CC1 = CC2 = hi-Z
(Note 1, 2)
CC1, CC2 active
(Note 1, 2)
(Note 1, 2, 6)
(Note 1, 2, 6)
(Note 1, 2, 6)
0.30
0.9
1.55
1.64
1.0
1.65
1.75
V
DD
x
0.73
V
DD
x
0.33
V
DD
x
0.29
0.1
+1
15
400
1.1
1.75
1.86
2.0
5
+1
3.0
15
UNITS
μA
V
μA
mV
μA
V
V
μA
%
mV
V
V
V
V
0.36
V
V
0.5
μA
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DS2714:
Quad Loose Cell NiMH Charger
PARAMETER
Presence Test Current, VP1-4
Reverse Leakage Current,
VP1, VP2, VP3, VP4
SYMBOL
I
PTST
I
LKGR
CONDITIONS
V
DD
= 0V, VPx = 1.5V
MIN
TYP
10
MAX
15
2
UNITS
μA
μA
ELECTRICAL CHARACTERISTICS: TIMING
Internal Timebase Period
Internal Timebase
Accuracy
Duty Factor, Fast Charge
Duty Factor, Pre-
Charge/Top-Off
Duty Factor, Maintenance
Charge
Cell Test Interval
Pre-Charge Time-out
Fast Charge Termination
Hold-Off Period
Fast Charge Flat Voltage
Time-out
Charge Timer Accuracy
Charge Timer Range
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
Note 7:
(4.0V
≤
V
DD
≤
5.5V; T
A
= -20°C to +70°C. Unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
t
BASE
(Note 5)
MIN
TYP
0.48
MAX
UNITS
s
-10
DF1
DF2
DF3
t
CTST
t
PCHG
t
THO
t
FLAT
V
CELL
not increasing
CCx
CCx
CCx Note 4
(Note 3)
V
CELL
< V
BAT-MIN
30.6
3.6
14.4
-5
t
CTMR-RANGE
0.5
0.234
0.0625
0.0078
31
34
4
16
+10
%
s
37.4
4.4
17.6
+5
10
minutes
minutes
minutes
%
h
Voltages relative to V
SS
.
Specification applicable during charge cycle with T
A
= 0°C to +70°C.
One time slot out of every 16 available slots gets a Cell Test.
One time slot out of every 32 available time slots gets a charge pulse.
0.48 seconds is one charge time slot. A complete cycle of 4 time slots (one charge time slot per cell) is 1.92 sec.
V
THM-MIN,
V
THM-MAX,
and V
THM-STOP
are fixed ratios of V
DD.
Their ranges never overlap.
I
MTST
current is applied as a source current and as a sink current within 5ms after power-up.
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DS2714:
Quad Loose Cell NiMH Charger
PIN DESCRIPTION
PIN
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
NAME
CC1
CC2
CC3
CC4
LED1
LED2
V
SS
LED3
LED4
DMSEL
CTST
TMR
V
DD
V
SS
VP1
VP2
VP3
VP4
THM1
THM2
FUNCTION
Charge Control 1.
Turn on and off the charge PNP for Cell 1.
Charge Control 2.
Turn on and off the charge PNP for Cell 2.
Charge Control 3.
Turn on and off the charge PNP for Cell 3.
Charge Control 4.
Turn on and off the charge PNP for Cell 4.
LED 1. Open drain output for LED.
Display Cell 1 status.
LED 2. Open drain output for LED.
Display Cell 2 status.
Device Ground.
Return current path for LEDx pins. Both VSS pins must be connected to ground.
LED 3. Open drain output for LED.
Display Cell 3 status.
LED 4. Open drain output for LED.
Display Cell 4 status.
Display Mode Select.
Select the LED blink rate.
Cell Test Resistor.
Cell test threshold set.
Timer Resistor.
Charge timer set.
Power-Supply Input.
Chip supply input (4.0V to 5.5V).
Device Ground.
Internally connected to Pin 7. Both VSS pins must be connected to ground.
Voltage Sense 1.
Positive terminal sense input for Cell 1.
Voltage Sense 2.
Positive terminal sense input for Cell 2.
Voltage Sense 3.
Positive terminal sense input for Cell 3.
Voltage Sense 4.
Positive terminal sense input for Cell 4.
Thermister 1.
Thermister input for Cell 1 and 2.
Thermister 2.
Thermister input for Cell 3 and 4.
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DS2714:
Quad Loose Cell NiMH Charger
Figure 1. Block Diagram
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