Datasheet

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GENERAL DESCRIPTION

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.

APPLICATIONS

Desktop/Stand-Alone Chargers (AAA/AA)

Digital Still Cameras

Music Players

Games

Toys

FEATURES

 Charge 1 or 2 NiMH Cells

 Detect and Avoid Charging Alkaline Cells

 Precharge Deeply Depleted Cells

 Fast Charge NiMH with -∆V Termination

Sensitivity of 2mV (typ)

 Monitor Voltage, Temperature, and Time for

Safety and Secondary Termination

 Regulate Charge Current:

Linear Control (DS2711)

Switch-Mode Control (DS2712)

 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

PIN CONFIGURATION

VP2

VP1

CC1

CC2

LED1

VSS

LED2

CSOUT

VN1

VN0

THM2

THM1

VDD

TMR

CTST

DMSEL

PIN DESCRIPTION

PIN NAME FUNCTION

CC1

Cell 1 Charge-Control Output

CC2

Cell 2 Charge-Control Output

LED1

Cell 1 Status

4 V

Ground Reference and Chip-

Supply Return

LED2

Cell 2 Status, Mode-Select Input

CSOUT

Current-Sense Output

VN1

Current-Sense + Input

VN0

Current-Sense - Input

DMSEL

Display-Mode Select

CTST

Cell Test Threshold Set

TMR

Charge Timer Set

Chip-Supply Input (4.0V to 5.5V)

THM1

Cell 1 Thermistor Input

THM2

Cell 2 Thermistor Input

15 VP1

Cell 1 Positive-Terminal Sense

Input

16 VP2

Cell 2 Positive-Terminal Sense

Input

DS2711/DS2712

Loose-Cell NiMH Chargers

SO (150 mils)

TSSOP (4.4mm)

19-5826; Rev 4/11

Summary of content (15 pages)

PAGE 1
9-5826; 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.
PAGE 2
DS2711/DS2712: Loose-Cell NiMH Chargers ABSOLUTE MAXIMUM RATINGS Voltage Range on All Pins Relative to VSS……………………………………………………………………-0.3V to +6V Voltage Range on DMSEL……………………………………………….……………………………………….VDD + 0.3V Continuous Sink Current CC1, CC2, LED1, LED2, and CSOUT………………………………............................20mA Operating Temperature Range………………………………………………………………………………-40°C to +85°C Storage Temperature Range……………………………………………………………………………….-55°C to +125°C Lead Temperature (soldering, 10s) ....................
PAGE 3
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-MIN (Notes 1, 4, 6) VTHM-MAX (Notes 1, 4, 6) VTHM-STOP (Notes 1, 4, 6) 0.30 ITMR-SUS IPTST Parallel: VDD ≥ 4.0V, Series: VDD ≥ 4.5V Reverse Leakage Current, VP1, VP2 ILKGR VDD = 0V, VP1 = 1.5V, VP2 = 3.
PAGE 4
DS2711/DS2712: Loose-Cell NiMH Chargers PARAMETER SYMBOL Charge Timer Accuracy Charge Timer Range CONDITIONS MIN RTMR = 100kΩ tCTMR-RANGE TYP MAX UNITS -5 +5 % 0.5 10 Hours ELECTRICAL CHARACTERISTICS: TIMING (continued) (4.0V ≤ VDD ≤ 5.5V, TA = -20°C to +70°C, unless otherwise noted.) Note 1: Note 2: Note 3: Note 4: Note 5: Note 6: Note 7: Note 8: Voltages relative to VSS. IMTST current is applied as a source current and as a sink current within 5ms after power-up.
PAGE 5
DS2711/DS2712: Loose-Cell NiMH Chargers Figure 2. State Diagram VDD < VPOR -VHYS (asynchronously from anywhere) POR VDD > VPOR (3.7V) Standby power CCx = Hi-Z LEDx = Hi-Z t < PCTimeout CCx = Hi-Z LEDx = No Battery PreCHG OR VBAT < 1.65V VBAT > 1.75V CCx = Active 12.5% Par., 25% Ser. LEDx = Charging VBAT < 1V t > PCTimeout OR T < 0 OR T > 50 OR VBAT > 1.
PAGE 6
DS2711/DS2712: Loose-Cell NiMH Chargers DETAILED DESCRIPTION Charge Algorithm Overview A charge cycle begins in one of three ways: with the application of power to the DS2711 with cell(s) already inserted, with the detection of cell insertion after power-up, or when exiting suspend mode with cell(s) inserted. The charge cycle begins with precharge qualification to prevent fast charging of deeply depleted cells or charging under extreme temperature conditions.
PAGE 7
DS2711/DS2712: Loose-Cell NiMH Chargers Parallel Charge Configuration The parallel configuration supports two slot stand-alone chargers. Charge pulses are fed alternately to each cell under the control of the CC1 and CC2 pins so the charge regimes occur in parallel. The duty cycle on CC1 and CC2 are independent of one another. Transitions from precharge to fast charge, fast charge to top-off, and top-off to maintenance occur independently for each cell.
PAGE 8
DS2711/DS2712: Loose-Cell NiMH Chargers DS2712 Parallel Charge Configuration with Switch-Mode Charge Current Regulation The example in Figure 5 uses the DS2712 to regulate charge current as a switching (buck) regulator. ICHG is set to 2A using RSNS = 0.056Ω. The effective charge current for each cell is ICHG x 0.484 = 968mA. The CSOUT comparator output switches OFF when the voltage across the sense resistor goes above 0.125V and back ON when the voltage drops below 0.100V.
PAGE 9
DS2711/DS2712: Loose-Cell NiMH Chargers Undervoltage Lockout (UVLO) The UVLO circuit serves as a power-up and brownout detector by monitoring VDD to prevent charging until VDD rises above VUVLO, or when VDD drops below VUVLO - VHYS. If UVLO is active, charging is prevented, the state machine is forced to the RESET state, and all charge timers are reset. A 10µs deglitch circuit provides noise immunity.
PAGE 10
DS2711/DS2712: Loose-Cell NiMH Chargers Charge Timer The charge timer monitors the duration of charge in fast and top-off charge phases, and is reset at the beginning of each phase. The timeout period is set with an external resistor connected from the TMR pin to VSS. Resistors can be selected to support fast-charge timeout periods of 0.5 to 10 hours and top-off charge timeout periods of 0.25 to 5 hours.
PAGE 11
DS2711/DS2712: Loose-Cell NiMH Chargers Cell Voltage Monitoring In the 2-cell series mode, the voltage difference between VP2 and VP1 is used to determine the Vcell2 voltage in the two-cell series stack. The voltage difference between VP1 and VN1 is used to determine the Vcell1 voltage. In the 1-cell series mode, the difference between VP1 and VN1 is used as the cell voltage. VP2 can be left disconnected in the 1-cell series mode.
PAGE 12
DS2711/DS2712: Loose-Cell NiMH Chargers Table 2. Charge Mode Selection LED2 PIN STRAPPING MODE Low 1-Cell Series Open 2-Cell Series High Parallel CC1 and CC2 Outputs The CC1 and CC2 operate as open-drain outputs that drive active low to connect the charge source to the battery cell. During charge, the behavior of the CC1 and CC2 outputs depends on the charge-mode configuration. In parallel mode, CC1 and CC2 are driven low in alternating time slots.
PAGE 13
DS2711/DS2712: Loose-Cell NiMH Chargers Table 3. Parallel Configuration, Each Cell MODE Cell Capacity Fast Precharge/Top-Off Maintenance CURRENT LIMIT 500mA 900mAH 1700mAH 2200mAH C/3.72 C/7.02 C/9.08 C/14.4 C/27.2 C/35.2 C/115 C/218 C/282 CURRENT LIMIT 1000mA 900mAH 1700mAH 2200mAH C/1.86 C/3.51 C/4.54 C/7.20 C/13.6 C/17.6 C/57.6 C/109 C/141 Series and Single Cell Charging Example In the series and single-cell modes, the effective fast charge current is equal to 0.
PAGE 14
DS2711/DS2712: Loose-Cell NiMH Chargers ORDERING INFORMATION PART DS2711Z DS2711Z+ DS2711Z/T&R DS2711Z+T&R DS2711E+ DS2711E+T&R DS2712Z DS2712Z+ DS2712Z/T&R DS2712Z+T&R DS2712E+ DS2712E+T&R TEMP RANGE -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C PIN-PACKAGE 16 SO 16 SO 16 SO 16 SO 16 TSSOP 16 TSSOP 16 SO 16 SO 16 SO 16 SO 16 TSSOP 16 TSSOP TOP MARK DS2711 DS2711 DS2711 D
PAGE 15
DS2711/DS2712: Loose-Cell NiMH Chargers REVISION HISTORY REVISION DATE 120808 4/11 DESCRIPTION Changed Figure 2 to include “T <0” as a condition to move from Pre-Charge to Fault state Updated the lead and soldering temperature information in the Absolute Maximum Ratings section; updated Figure 1; updated the Internal Oscillator and Clock Generation section; added the Package Information table PAGES CHANGED 6 3, 5, 10, 14 15 of 15 Maxim cannot assume responsibility for use of any circuitry other than cir