Rainbow Electronics DS2710 User Manual

General Description

The DS2710 is ideal for in-system charging of single-cell nickel metal hydride (NiMH) cells for low-current portable applications. Inputs to the DS2710 include USB voltage sources and 5V regulated adapters. Temperature, voltage, and charge time are monitored to provide proper fast-charging control algorithms for single-cell NiMH or nickel cadmium (NiCd) batteries. The DS2710 includes battery tests to detect defective or inappropriate cells such as alkaline primary batteries.

Applications

Small Rechargeable Devices

Voice Recorders

Cordless Mouse

Battery-Powered Toys

Features

♦ Charges Single-Cell NiMH Cells

♦ Switch-Mode Topologies Supported by Hysteretic

Control Technique

♦ Precharges Deeply Depleted Cells

♦ Fast-Charges NiMH with -ΔV Termination

Sensitivity of 2mV (typ)

♦ Monitors Voltage, Temperature, and Time for

Safety and Secondary Termination

♦ Regulates Charge Current

♦ Designed for External pMOS

♦ Rail-to-Rail MOSFET Driver

♦ Tiny 10-Pin TDFN Package (3mm x 4mm)

DS2710

Single-Cell NiMH Charger

________________________________________________________________

Maxim Integrated Products

Pin Configuration

Ordering Information

DS2710

VP1

THM

VN0 VN1

SENSE

CHARGE SOURCE

NiMH CELL

GROUND

Typical Operating Circuit

Rev 0; 4/08

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

Denotes a lead-free/RoHS-compliant package.

T&R = Tape and reel.

EP = Exposed pad.

PART PIN-PACKAGE

DS2710G+ 10 TDFN-EP*

DS2710G+T& R 10 TDFN-EP*

TOP VIEW

110

2 9 VN1CS

3 8 VN0V

4 7 TMRTHM

*EP

5 6 CTESTSTATUS

*EXPOSED PAD.

DS2710

TDFN

(3mm × 4mm)

VP1V

DS2710

Single-Cell NiMH Charger

2 _______________________________________________________________________________________2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

RECOMMENDED DC OPERATING CONDITIONS

(4.0V ≤ VDD≤ 5.5V, TA= -20°C to +70°C.)

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 absolute maximum rating conditions for extended periods may affect device reliability.

Voltage Range on All Pins Relative to VSS............-0.3V to +6.0V

Continuous Source/Sink Current CS ...................................20mA

Continuous Source Current STATUS ..................................10mA

Operating Temperature Range ...........................-40°C to +85°C

Storage Temperature Range .............................-55°C to +125°C

Soldering Temperature...........................Refer to the IPC/JEDEC

J-STD-020 Specification.

DC ELECTRICAL CHARACTERISTICS

(4.0V ≤ VDD≤ 5.5V, TA= -20°C to +70°C, unless otherwise noted.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Supply Voltage VDD (Note 1) 4.0 5.5 V

Input Voltage Range CTEST, TMR, THM, VP1, VN1 -0.3 VDD V

Supply Current, VDD I

UVLO Threshold V

UVLO Hysteresis V

Output-Voltage Low, CS V

Output-Voltage High, CS V

Output-Voltage Low, STATUS V

Output-Voltage High, STATUS V

Threshold Voltage,

-V Termination

Current-Sense Reference Voltage

Hysteres is, Current-Sense Comparator

Propagation Time, Current-Sense Comparator to Dri ver Output

CS Pin Pul lup Current ICS VDD < V

STATUS Pin Pulldown Current I

Depleted Cell Voltage Thresho ld V

Overcharge Voltage Threshold

Open Socket Voltage Threshold

Offset, V

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Operating mode (Note 2) 250 1000 μA

VDD rising (Note 1) 3.5 3.9 V

UVLO

VDD falling from above V

UHYS

VDD = 5.0V, IOL = +20mA (Note 1) 1.0 V

OL1

VDD = 5.0V, IOL = -20mA (Note 1) 4.0 V

OH1

VDD = 5.0V, IOL = +2mA (Notes 1, 3) 0.50 V

OL2

VDD = 5.0V, IOH = -2mA (Notes 1, 3) 4.0 V

OH2

MAX-O PEN

- V

MAX-CHARGE

After t

-V

(Notes 1, 5)

IREF

HYS-

COMP

PDLY

STAT

LOW

MAX-

OPEN

MAX-

CHARGE

VOS (Note 7) 98 100 102 mV

Centered ~ 0.113V 18 23 27 mV

2mV overdrive/underdrive at trip thresho ld (Notes 4, 6)

VDD < V

VP1 - VN1 0.9 1.0 1.1 V

VP1 - VN1, CS = high (Note 7) 1.55 1.65 1.75 V

VP1 - VN1, CS = low (Note 7) 1.64 1.75 1.86 V

(Note 4) 1.0 2.0 3.0 mV

THO

UVLO

30 mV

UVLO

125 mV

-6 +6 %

0.1 μs

(Note 4) 2 10 μA

DS2710

Single-Cell NiMH Charger

_______________________________________________________________________________________ 3

Note 1: Voltages relative to VSS. Note 2: Specification does not include CS and STATUS pin currents. Note 3: STATUS pin is active high. Note 4: Specification is guaranteed by design. Note 5: Specification applicable during charge cycle with T

= 0°C to +70°C.

Note 6: 50mV overdrive while connected to a pMOS transistor (such as ZXM62P02 from Zetex). Note 7: V

BAT-MAX1

and V

BAT-MAX1

ranges never overlap.

Note 8: VT

HM-MIN

, V

THM-MAX

, and V

THM-STOP

are fixed ratios of VDD. Their ranges never overlap.

Note 9: Maximum allowable leakage on TMR to maintain SUSPEND state.

DC ELECTRICAL CHARACTERISTICS (continued)

(4.0V ≤ VDD≤ 5.5V, TA= -20°C to +70°C, unless otherwise noted.)

ELECTRICAL CHARACTERISTICS: TIMING

(4.0V ≤ VDD≤ 5.5V, TA= -20°C to +70°C, unless otherwise noted.)

Cold Temperature Detect Threshold

Hot Temperature No-Start Threshold

Hot Temperature Safety Shutdown Threshold

SUSPEND Current Threshold I

Presence-Test Current, VP1 VDD 4.0V 1.0 10 15 μA

Reverse-Leakage Current, VP1 V

Impedance-Voltage Test Range V

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

THM-MIN

THM-MAX

THM-ST OP

SUSP END

(Notes 1, 5, 8) 0.73 V

(Notes 1, 5, 8) 0.30 0.33 0.36 V

(Notes 1, 5, 8) 0.29 V

(Note 9) 0.1 0.5 μA

= 0V, VP1 = 1.5V 2 μA

32 400 mV

CTEST

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Internal Time-Base Period t

Internal Time-Base Accuracy -10 +10 %

CS Output Duty Factor

CELL TEST Interval t

PRECHARGE Timeout t

FAST-CHARGE Termination Hold-Off Period

FAST-CHARGE Flat Voltage Timeout

Charge-Timer Period t

Charge-Timer Accuracy R

Charge-Timer Range t

CTMR -R ANGE

Toggle Rate, Charging f

Toggle Rate, FAULT State f

0.96 Seconds

BASE

DF1 FAST-CHARGE 96.9

DF2 PRECHARGE/TOP-OFF 25.0

DF3 MAINTENANCE 1.56

31 Seconds

CTST

PCHG

4 Minutes

THO

FLAT

CTMR

< V

CELL

not increasing 16 Minutes

CELL

= 40k 1.0 Hours

TMR

= 40k -6 +6 %

TMR

34 Minutes

LOW

0.5 5.0 Hours

1 Hz

CHARGE

4 Hz

FAULT

DS2710

Single-Cell NiMH Charger

4 _______________________________________________________________________________________

Pin Description

Figure 1. Block Diagram

PIN NAME FUNCTION

1 VSS Device Ground. Connect s directly to the negative terminal of the charge source.

2 CS Charge Source. Feedback control for switching circuitry.

3 V

4 THM Thermistor Input. Connects to a thermistor located near the cell and a resistor-div ider from the VDD pin.

5 STATUS Status Output. Drives an external LED or microprocessor input to indicate charge status.

6 CTEST Impedance Test. Connects to VSS through an external resistor to set the impedance-test threshold.

7 TMR Fast-Charge Timer. Connects to VSS through an external res istor to set the fast-charge timeout period.

8 VN0 Current-Sense Negative Input. Connects to the charge source s ide of the external sense resistor.

9 VN1 Current-Sense Positive Input. Connects to the cell side of the external sense resistor.

10 VP1 Cel l Voltage Sense. The voltage of the cel l is monitored through thi s input pin.

— EP Exposed Pad. Connects to VSS.

Power-Supply Input. Connects to the posit ive terminal of the charge source through a decoupling

network.

STATUS

CTEST

TMR

0.1μA

BIAS

UVLO

OSCILLATOR

STATE MACHINE

PRESENSE TEST

PRECHARGE

FAST-CHARGE AND

CELL TESTS

TOP-OFF CHARGE

MAINTENANCE CHARGE

SUSPEND

WATCHDOG

ABORT

0.125V

VOLTAGE

AND

TEMPERATURE

MEASUREMENT

DUTYFACTOR CONTROL

DS2710

PTST

VP1

VN1

THM

VN0

3.5V

STATUS

CELL TEST

CHARGE

TIMER

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