DATA SHEET
bq25071 1-A, Single-Input, Single-Cell LiFePO4 Linear Battery Charger with 50 mA LDO
1 Features
- Single Cell LiFePO4 Charging Algorithm
- 30V Input Rating, With 10.5 V Overvoltage Protection (OVP)
- 50mA Integrated Low Dropout Linear Regulator (LDO)
- Programmable Charge Current Through ISET and EN Terminals
- 7% Charge Current Regulation Accuracy
- Thermal Regulation and Protection
- Soft-Start Feature to Reduce Inrush Current
- Battery NTC Monitoring
- Charging Status Indication
2 Applications
- Smart Phones
- Mobile Phones
- Portable Media Players
- Low Power Handheld Devices
3 Description
The bq25071 is a highly integrated, linear, LiFePO4 battery charger targeted at space-limited portable applications. It accepts power from either a USB port or AC adapter and charges a single-cell LiFePO4 battery with up to 1 A of charge current. The 30 V input rating with 10.5 V input overvoltage protection supports low-cost unregulated adapters.
The bq25071 has a single power output that simultaneously charges the battery and powers the system. The input current is programmable from 100 mA up to 1 A using the ISET input or configurable for USB500. There is also a 4.9 V ±10% 50 mA LDO integrated into the IC for supplying low power external circuitry.
The LiFePO4 charging algorithm removes the current taper typically seen as part of the constant voltage mode control used in Li-Ion battery charge cycles which reduces charge time significantly. Instead, the battery is fast charged to the overcharge voltage and then allowed to relax to a lower float charge voltage threshold. The charger integrates the power stage with the charge current and voltage sense to achieve a high level of accuracy in the current and voltage regulation loops. An internal control loop monitors the IC junction temperature through the charge cycle and reduces the charge current if an internal temperature threshold is exceeded.
Device Information(1)
| PART NUMBER | PACKAGE | BODY SIZE (NOM) |
|---|---|---|
| bq25071 | WSON (10) | 2.00mm x 3.00mm |
- For all available packages, see the orderable addendum at the end of the datasheet.
4 Application Schematic
5 Revision History
| DATE | REVISION | NOTES |
|---|---|---|
| July 2014 | * | Initial release. |
6 Device Comparison Table
| PART NUMBER | VBAT(OVCH) | VBAT(FLOAT) | V(OVP) | V(LDO) |
|---|---|---|---|---|
| bq25071DQCR | 3.7 V | 3.5 V | 10.5 V | 4.9 V |
| bq25071DQCT | 3.7 V | 3.5 V | 10.5 V | 4.9 V |
7 Pin Configuration and Functions
bq25071
(TOP VIEW)
Pin Functions
| PIN | I/O | DESCRIPTION | |
|---|---|---|---|
| NAME | NO. | ||
| IN | 1 | I | Input power supply. IN is connected to the external DC supply (AC adapter or USB port). Bypass IN to GND with at least a 0.1 μF ceramic capacitor. |
| ISET | 2 | O | Input current programming bias pin. Connect a resistor from ISET to GND to program the input current limit when the user programmable mode is selected by grounding the EN pin. The resistor range is between 1 kΩ and 10 kΩ to set the current between 100 mA and 1 A. |
| GND | 3, 9 | – | Ground pin. Connect to the thermal pad and the ground plane of the circuit. |
| LDO | 4 | O | LDO output. LDO is regulated to 4.9V and drives up to 50 mA. Bypass LDO to GND with a 0.1 μF ceramic capacitor. LDO is enabled when V(UVLO) < VIN < V(OVP). |
| TS | 5 | I | Battery pack NTC monitoring input. Connect a resistor divider from LDO to GND with TS connected to the center tap to set the charge temperature window. The battery pack NTC is connected in parallel with the bottom resistor of the divider. See the Detailed Design Procedure section for details on the selecting the proper component values. |
| BAT | 6 | I | BAT is the sense input for the battery voltage. Connect BAT and OUT to the battery. |
| EN | 7 | I | Enable input. Drive EN high to disable the IC. Connect EN to GND to place the bq25071 in the user programmable mode using the ISET input where the input current is programmed. Leave EN floating to place the bq25071 in USB500 mode. See the Input Current Limit Control (EN) section for details on using the EN interface. |
| CHG | 8 | O | Charge status indicator open-drain output. CHG is pulled low while the device is charging the battery. CHG goes high impedance when the battery is fully charged. |
| OUT | 10 | O | System output connection. Bypass the OUT to GND with a 1 μF ceramic capacitor. Connect OUT and BAT together. |
| Thermal Pad | Pad | – | There is an internal electrical connection between the exposed thermal pad and the GND pin of the device. The thermal pad must be connected to the same potential as the GND pin on the printed circuit board. Do not use the thermal pad as the primary ground input for the device. GND pin must be connected to ground at all times. |
8 Specifications
8.1 Absolute Maximum Ratings(1)
over operating free-air temperature range (unless otherwise noted)| MIN | MAX | UNIT | ||
|---|---|---|---|---|
| Input Voltage | IN (with respect to GND) | –0.3 | 30 | V |
| EN, TS (with respect to GND) | –0.3 | 7 | V | |
| Output Voltage | BAT, OUT, LDO, CHG, ISET (with respect to GND) | –0.3 | 7 | V |
| Input Current (Continuous) | IN | 1.2 | A | |
| Output Current (Continuous) | BAT | 1.2 | A | |
| Output Current (Continuous) | LDO | 100 | mA | |
| Output Sink Current | CHG | 5 | mA | |
| Junction temperature, TJ | –40 | 150 | °C | |
(1) 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 under recommended operating conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. All voltage values are with respect to the network ground pin unless otherwise noted.
8.2 Handling Ratings
| MIN | MAX | UNIT | |||
|---|---|---|---|---|---|
| TSTG | Storage temperature | –65 | 150 | °C | |
| VESD | Electrostatic discharge | Human body model (HBM), per ANSI/ESDA/JEDEC JS-001, all pins (1) | 0 | 3000 | V |
| Charged device model (CDM), per JEDEC specification JESD22-C101, all pins (2) | 0 | 1000 | V | ||
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
(2) JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
8.3 Recommended Operating Conditions
| MIN | MAX | UNITS | ||
|---|---|---|---|---|
| VIN | IN voltage | 3.75(1) | 28 | V |
| IN operating voltage | 3.75(1) | 10.2 | ||
| IIN | Input current, IN | 1 | A | |
| IOUT | Output Current in charge mode, OUT | 1 | A | |
| TJ | Junction Temperature | 0 | 125 | °C |
(1) Charge current may be limited at low input voltages due to the dropout of the device.
8.4 Thermal Information
| THERMAL METRIC(1) | bq25071 | UNIT | |
|---|---|---|---|
| DQC (10 PINS) | |||
| RθJA | Junction-to-ambient thermal resistance | 61.6 | °C/W |
| RθJC(top) | Junction-to-case (top) thermal resistance | 65.5 | |
| RθJB | Junction-to-board thermal resistance | 22.8 | |
| ψJT | Junction-to-top characterization parameter | 1.5 | |
| ψJB | Junction-to-board characterization parameter | 22.7 | |
| RθJC(bot) | Junction-to-case (bottom) thermal resistance | 5.5 | |
(1) For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.
8.5 Electrical Characteristics
Over junction temperature range 0°C ≤ TJ ≤ 125°C and recommended supply voltage (unless otherwise noted)| PARAMETER | TEST CONDITIONS | MIN | TYP | MAX | UNITS | |
|---|---|---|---|---|---|---|
| INPUT | ||||||
| V(UVLO) | Under-voltage lock-out | VIN: 0 V → 4 V | 3.15 | 3.30 | 3.55 | V |
| VHYS(UVLO) | Hysteresis on V(UVLO) | VIN: 4 V → 0 V | 250 | mV | ||
| VIN(SLP) | Valid input source threshold VIN(SLP) above VBAT | Input power good if VIN > VBAT + VIN(SLP)
V(BAT) = 3.6 V, VIN: 3.5 V → 4 V |
30 | 75 | 150 | mV |
| VHYS(INSLP) | Hysteresis on VIN(SLP) | V(BAT) = 3.6 V, VIN: 4 V → 3.5 V | 18 | 32 | 54 | mV |
| tDGL(NO-IN) | Delay time, input power loss to charger turn-off | Time measured from VIN: 5 V → 2.5 V 1 μs fall-time | 32 | ms | ||
| VOVP | Input over-voltage protection threshold | VIN: 5 V → 11 V | 10.2 | 10.5 | 10.8 | V |
| VHYS(OVP) | Hysteresis on OVP | VIN: 11 V → 5 V | 100 | mV | ||
| QUIESCENT CURRENT | ||||||
| IBAT(PDWN) | Battery current into BAT, No input connected | VIN = 0 V(1), V(CHG) = Low, TJ = 85°C | 6 | μA | ||
| IIN(STDBY) | Standby current into IN pin | EN = HI, VIN = 5.5V | 0.25 | mA | ||
| EN = HI, VIN ≤ V(OVP) | 0.5 | |||||
| EN = HI, VIN > V(OVP) | 2 | |||||
| BATTERY CHARGER FAST-CHARGE | ||||||
| VBAT(REG) | Battery charge regulation voltage | TA = 0°C to 125°C, IOUT = 50 mA | 3.455 | 3.5 | 3.545 | V |
| TA = 25°C | 3.455 | 3.5 | 3.539 | |||
| VBAT(OVCH) | Battery overcharge voltage threshold | 3.62 | 3.7 | 3.78 | V | |
| IIN(RANGE) | User programmable input current limit range | R(ISET) = 1 kΩ to 1 0kΩ, EN = VSS | 100 | 1000 | mA | |
| IIN(LIM) | Input current limit, or fast-charge current | EN = FLOAT | 435 | 467 | 500 | mA |
| EN = VSS | KISET/RISET | |||||
| KISET | Fast charge current factor | R(ISET) = 1 kΩ to 10 kΩ, EN = VSS | 900 | 1000 | 1100 | AΩ |
| VDO(IN-OUT) | VIN – VOUT | VIN = 3.55 V, IOUT = 0.75 A | 500 | 900 | mV | |
| ISET SHORT CIRCUIT PROTECTION | ||||||
| RISET(MAX) | Highest resistor value considered a short fault | R(ISET): 900 Ω → 300 Ω, IOUT latches off, Cycle power to reset, Fault range > 1.10 A | 430 | 700 | Ω | |
| IOUT(CL) | Maximum OUT current limit regulation (Clamp) | 1.07 | 2 | A | ||
| PRE-CHARGE AND CHARGE DONE | ||||||
| V(LOWV) | Pre-charge to fast-charge transition threshold | 0.5 | 0.7 | 0.9 | V | |
| I(PRECHARGE) | Precharge current to BAT during precharge mode | V(BAT) = 0 V to 0.7 V | 41.5 | 45 | 48.5 | mA |
| RECHARGE OR REFRESH | ||||||
| V(RCH) | Recharge detection threshold | V(BAT) falling | 3.1 | 3.3 | 3.5 | V |
| LDO | ||||||
| V(LDO) | LDO Output Voltage | VIN = 5 V to 10.5 V, I(LDO) = 0 mA to 50 mA |
4.7 | 4.9 | 5.1 | V |
| I(LDO) | Maximum LDO Output Current | 60 | mA | |||
| V(DO) | Dropout Voltage | VIN = 4.5V, I(LDO) = 50 mA | 200 | 350 | mV | |
| LOGIC LEVELS ON EN | ||||||
| VIL | Logic low input voltage | 0.4 | V | |||
| VIH | Logic high input voltage | 1.4 | V | |||
| V(FLT) | Logic FLOAT input voltage | 600 | 850 | 1100 | mV | |
| I(FLTlkg) | Maximum leakage sink or source current to keep in FLOAT | 1 | µA | |||
| IEN(DRIVE) | Minimal drive current from an external device for Low or High | 8 | µA | |||
| BATTERY-PACK NTC MONITOR (TS) | ||||||
| V(COLD) | TS Cold Threshold | V(TS) Rising | 24.5 | 25 | 25.5 | %VLDO |
| V(CUTOFF) | TS Cold Cutoff Threshold | V(TS) Falling | 1 | %VLDO | ||
| V(HOT) | TS Hot Threshold | V(TS) Falling | 12 | 12.5 | 13 | %VLDO |
| VHOT(HYS) | TS Hot Cutoff Threshold | V(TS) Rising | 1 | %VLDO | ||
| CHG OUTPUT | ||||||
| VOL | Output LOW voltage | I(SINK) = 1 mA | 0.45 | V | ||
| IIH | Leakage current | CHG = 5 V | 1 | μA | ||
| THERMAL REGULATION | ||||||
| TJ(REG) | Temperature Regulation Limit | TJ rising | 125 | °C | ||
| TJ(OFF) | Thermal shutdown temperature | TJ rising | 155 | °C | ||
| TJ(OFF-HYS) | Thermal shutdown hysteresis | TJ falling | 20 | °C | ||
(1) Force V(CHG)
8.6 Timing Requirements
| MIN | TYP | MAX | UNIT | |||
|---|---|---|---|---|---|---|
| INPUT | ||||||
| tBLK(OVP) | Input overvoltage blanking time | 100 | μs | |||
| tREC(OVP) | Input overvoltage recovery time | Time measured from VIN: 11 V → 5 V 1 μs fall-time to LDO = HI, V(BAT) = 3.5 V |
100 | μs | ||
| ISET SHORT CIRCUIT PROTECTION | ||||||
| tDGL(SHORT) | Deglitch time transition from I(SET) short to IOUT disable | Clear fault by cycling V(BUS) or EN | 1.5 | ms | ||
| PRE-CHARGE AND CHARGE DONE | ||||||
| tDGL1(LOWV) | Deglitch time on pre-charge to fast-charge transition | 25 | ms | |||
| tDGL2(LOWV) | Deglitch time on fast-charge to pre-charge transition | 25 | ms | |||
| RECHARGE OR REFRESH | ||||||
| tDGL(RCH) | Deglitch time, recharge threshold detected | V(BAT) falling to New Charge Cycle | 25 | ms | ||
| BATTERY-PACK NTC MONITOR (TS) | ||||||
| tdgl(TS) | Deglitch for TS Fault | Fault detected on TS to stop charge | 25 | ms | ||
8.7 Typical Characteristics
VIN = 5 V, VBAT = 3.2 V, I(CHG) = 280 mA, Typical Application Circuit
| VIN = 4.5 V | IOUT = 1 A | |
| VIN = 5 V | ||
