Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsPMICsPMIC - battery management Charge management Li-Ion, Multi-Chemistry VQFN 20 (3.5x3.5) Surf

6 7 8 9 10

20 19 18 17 16

ACN

ACP

CMSRC

ACDRV

ACOK

ACDET

IOUT

SDA

SCL

ILIM

BATDRV

SRN

SRP

GND

LODRV

REGN

BTST

HIDRV

PHASE

VCC

bq24735

www.ti.com

SLUSAK9A –SEPTEMBER 2011–REVISED JANUARY 2013

1-4 Cell Li+ Battery SMBus Charge Controller for Supporting Turbo Boost Mode with

N-Channel Power MOSFET Selector

Check for Samples: bq24735

FEATURES

DESCRIPTION

The bq24735 is a high-efficiency, synchronous

• Adapter and Battery Provides Power to

battery charger, offering low component count for

System Together to Support Intel

CPU Turbo

space-constraint, multi-chemistry battery charging

Boost Mode

applications.

• SMBus Host-Controlled NMOS-NMOS

The bq24735 supports Turbo Boost by allowing

Synchronous Buck Converter with

battery discharge energy to system when system

Programmable 615kHz, 750kHz, and 885kHz

power demand is temporarily higher than adapter

Switching Frequencies

maximum power level so that adapter will not crash.

• Automatic N-channel MOSFET Selection of

The bq24735 utilizes two charge pumps to separately

System Power Source from Adapter or Battery

drive n-channel MOSFETs (ACFET, RBFET and

Driven by Internal Charge Pumps

BATFET) for automatic system power source

• Enhanced Safety Features for Over Voltage

selection.

Protection, Over Current Protection, Battery,

SMBus controlled input current, charge current, and

Inductor and MOSFET Short Circuit Protection

charge voltage DACs allow for very high regulation

• Programmable Input Current, Charge Voltage,

accuracies that can be easily programmed by the

Charge Current Limits

system power management micro-controller.

– ±0.5% Charge Voltage Accuracy up to 19.2V

The bq24735 uses internal input current register or

– ±3% Charge Current Accuracy up to 8.128A

external ILIM pin to throttle down PWM modulation to

reduce the charge current.

– ±3% Input Current Accuracy up to 8.064A

– ±2% 20x Adapter Current or Charge Current

The bq24735 charges one, two, three or four series

Amplifier Output Accuracy Li+ cells, and is available in a 20-pin, 3.5x3.5 mm

QFN package.

• Programmable Battery Depletion Threshold,

and Battery LEARN Function

PIN CONFIGURATION

• Programmable Adapter Detection and

Indicator

• Integrated Soft Start

• Integrated Loop Compensation

• Real Time System Control on ILIM pin to Limit

Charge Current

• AC Adapter Operating Range 4.5V-24V

• 5µA Off-State Battery Discharge Current

• 0.65mA (0.8mA max) Adapter Standby

Quiescent Current

• 20-pin 3.5 x 3.5 mm

QFN Package

APPLICATIONS

• Portable Notebook Computers, UMPC, Ultra-

Thin Notebook, and Netbook

• Handheld Terminal

• Industrial and Medical Equipment

• Portable Equipment

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

2Intel is a registered trademark of Intel.

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.

Summary of content (42 pages)

PAGE 1
bq24735 www.ti.com SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 1-4 Cell Li+ Battery SMBus Charge Controller for Supporting Turbo Boost Mode with N-Channel Power MOSFET Selector Check for Samples: bq24735 FEATURES DESCRIPTION • The bq24735 is a high-efficiency, synchronous battery charger, offering low component count for space-constraint, multi-chemistry battery charging applications.
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bq24735 SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 www.ti.com These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. DEVICE INFORMATION Reverse Input Protection Adapter + Adapter - Q6 BSS138W R12 1M R13 3.01M Q1 (ACFET) FDS6680A * Ri 2? Ci 2.2µF C17 2200pF D2 BAT54C Q2 (RBFET) FDS6680A RAC 10m? C16 0.1µF C1 0.
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bq24735 www.ti.com SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 D3 PDS1040 Adapter + Adapter - * Q1 (ACFET) FDS6680A C17 2200 pF Ri 2? Ci 2.2µF RAC 10 mW SYSTEM C16 0.1µF C1 0.1µF * R10 4.02 kW C3 0.1µF * C5 1µF ACN C2 0.1µF Total Csys 220µF R9 10 Ω VCC R6 4.02 kW BATDRV ACP R11 4.02 kW CMSRC Q5 (BATFET) FDS6680A C15 0.01µF C6 1µF REGN ACDRV R1 430 kW BTST D1 BAT54 C8 10uF ACDET R2 66.5 kW HIDRV R8 100 kW ILIM R7 549 kW +3.
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bq24735 SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 Q1 (ACFET) FDS6680A Adapter + C17 2200pF www.ti.com Q2 (RBFET) FDS6680A RAC 10 mW C16 0.047µF C1 0.1 µF Adapter - SYSTEM C3 0.1µF * Din BAT54A C2 0.1µF R10 4.02 kW Total Csys 220 µF R9 4.7 W C5 1µF ACN VCC ACP BATDRV * Q5 (BATFET) Si4435DDY R6 4.02 kW R11 4.02 kW R12 100 kW C6 1µF CMSRC D2 SL42 REGN D1 BAT54 ACDRV R1 430 kW BTST C8 10uF ACDET R2 487 kW HIDRV R8 100 kW ILIM R7 549 kW +3.
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bq24735 www.ti.com SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 THERMAL INFORMATION bq24735 THERMAL METRIC (1) (2) θJA Junction-to-ambient thermal resistance θJCtop Junction-to-case (top) thermal resistance (3) 56.9 (4) Junction-to-board thermal resistance ψJT Junction-to-top characterization parameter (5) ψJB Junction-to-board characterization parameter (1) (2) (3) (4) (5) (6) (7) UNITS 46.8 θJB θJCbot RGR (20 PIN) 46.6 Junction-to-case (bottom) thermal resistance °C/W 0.
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bq24735 SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 www.ti.com ELECTRICAL CHARACTERISTICS 4.5 V ≤ VVCC ≤ 24 V, 0°C ≤ TJ ≤ 125°C, typical values are at TA = 25°C, with respect to GND (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT OPERATING CONDITIONS VVCC_OP VCC Input voltage operating range 4.5 24 V 19.2 V 16.884 V CHARGE VOLTAGE REGULATION VBAT_REG_RNG Battery voltage range 1.
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bq24735 www.ti.com SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 ELECTRICAL CHARACTERISTICS (continued) 4.5 V ≤ VVCC ≤ 24 V, 0°C ≤ TJ ≤ 125°C, typical values are at TA = 25°C, with respect to GND (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX 6.5 UNIT REGN REGULATOR VREGN_REG IREGN_LIM REGN regulator voltage REGN current limit 5.
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bq24735 SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 www.ti.com ELECTRICAL CHARACTERISTICS (continued) 4.
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bq24735 www.ti.com SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 ELECTRICAL CHARACTERISTICS (continued) 4.
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bq24735 SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 www.ti.com ELECTRICAL CHARACTERISTICS (continued) 4.
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bq24735 www.ti.com SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 TYPICAL CHARACTERISTICS Table 1. Table of Graphs FIGURE NO.
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bq24735 SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 www.ti.com CH1: PHASE, 10V/div, CH2: LODRV, 5V/div, CH3: HIDRV, 10V/div, CH4: inductor current, 2A/div, 400ns/div Figure 9. Continuous Conduction Mode Switching Waveforms CH1: PHASE, 10V/div, CH2: LODRV, 5V/div, CH4: inductor current, 2A/div, 4us/div Figure 11. 100% Duty and Refresh Pulse CH1: PHASE, 10V/div, CH2: LODRV, 5V/div, CH3: HIDRV, 10V/div, CH4: inductor current, 1A/div, 400ns/div Figure 10.
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bq24735 www.ti.com SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 CH3: adapter current, 2A/div, CH4: battery current, 2A/div, 10ms/div Figure 15. Buck to Boost Mode CH3: adapter current, 2A/div, CH4: battery current, 2A/div, 10ms/div Figure 16. Boost to Buck Mode Pin Functions – 20-Pin QFN PIN NO. DESCRIPTION NAME 1 ACN Input current sense resistor negative input. Place an optional 0.1µF ceramic capacitor from ACN to GND for commonmode filtering. Place a 0.
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bq24735 SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 www.ti.com Pin Functions – 20-Pin QFN (continued) PIN NO. 12 SRN Charge current sense resistor negative input. SRN pin is for battery voltage sensing as well. Connect SRN pin to a 7.5 Ω resistor first then from resistor another terminal connect a 0.1µF ceramic capacitor to GND for common-mode filtering and connect to current sensing resistor. Connect a 0.1µF ceramic capacitor between current sensing resistor to provide differential mode filtering.
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bq24735 www.ti.com SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 FUNCTIONAL BLOCK DIAGRAM 135 1.07 Figure 17.
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bq24735 SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 www.ti.com DETAILED DESCRIPTION SMBus Interface The bq24735 operates as a slave, receiving control inputs from the embedded controller host through the SMBus interface. The bq24735 uses a simplified subset of the commands documented in System Management Bus Specification V1.1, which can be downloaded from www.smbus.org. The bq24735 uses the SMBus Read-Word and Write-Word protocols (see Figure 18) to communicate with the smart battery.
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bq24735 www.ti.com SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 Figure 19.
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bq24735 SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 www.ti.com Setting Charger Options By writing ChargeOption() command (0x12H or 0b00010010), bq24735 allows users to change several charger options after POR (Power On Reset) as shown in Table 3. Table 3. Charge Options Register (0x12H) BIT BIT NAME DESCRIPTION [15] ACOK Deglitch Time Adjust Adjust ACOK deglitch time. After POR, the first time the adapter plug in occurs, deglitch time is always 150ms no matter if this bit is 0 or 1.
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bq24735 www.ti.com SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 Table 3. Charge Options Register (0x12H) (continued) BIT BIT NAME DESCRIPTION [0] Charge Inhibit 0: Enable Charge 1: Inhibit Charge Setting the Charge Current To set the charge current, write a 16bit ChargeCurrent() command (0x14H or 0b00010100) using the data format listed in Table 4. With 10mΩ sense resistor, the bq24735 provides a charge current range of 128mA to 8.128A, with 64mA step resolution.
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bq24735 SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 www.ti.com Setting the Charge Voltage To set the output charge regulation voltage, write a 16bit ChargeVoltage() command (0x15H or 0b00010101) using the data format listed in Table 5. The bq24735 provides charge voltage range from 1.024V to 19.200V, with 16mV step resolution. Sending ChargeVoltage() below 1.024V or above 19.2V clears the register and terminates charging. Upon POR, charge voltage limit is 0V.
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bq24735 www.ti.com SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 To set the input current limit, write a 16-bit InputCurrent() command (0x3FH or 0b00111111) using the data format listed in Table 6. When using a 10mΩ sense resistor, the bq24735 provides an input-current limit range of 128mA to 8.064A, with 128mA resolution. The suggested input current limit is set to no less than 512mA. Sending InputCurrent() below 128mA or above 8.064A clears the register and terminates charging.
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bq24735 SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 www.ti.com Adapter Detect and ACOK Output The bq24735 uses an ACOK comparator to determine the source of power on VCC pin, either from the battery or adapter. An external resistor voltage divider attenuates the adapter voltage before it goes to ACDET. The adapter detect threshold should typically be programmed to a value greater than the maximum battery voltage, but lower than the maximum allowed adapter voltage.
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bq24735 www.ti.com SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 The gate drive voltage on ACFET and RBFET is VCMSRC + 6V. If the ACFET/RBFET have been turned on for 20ms, and the voltage across gate and source is still less than 5.9V, ACFET and RBFET will be turned off. After 1.3s delay, it resumes turning on ACFET and RBFET. If such a failure is detected seven times within 90 seconds, ACFET/RBFET will be latched off and an adapter removal and system shut down is required to force ACDET < 0.
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bq24735 SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 www.ti.
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bq24735 www.ti.com SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 Converter Operation The synchronous buck PWM converter uses a fixed frequency voltage mode control scheme and internal type III compensation network. The LC output filter gives a characteristic resonant frequency 1 ¦o = 2p Lo Co (3) The resonant frequency fo is used to determine the compensation to ensure there is sufficient phase margin and gain margin for the target bandwidth.
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bq24735 SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 www.ti.com Both CCM and DCM are synchronous operation with LSFET turn-on every clock cycle. If the average charge current goes below 125mA on 10mΩ current sensing resistor or the battery voltage falls below 2.5V, the LSFET keeps turn-off. The battery charger operates in non-synchronous mode and the current flows through the LSFET body diode.
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bq24735 www.ti.com SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 If frequency is reduced, for a fixed inductor the current ripple is increased. Inductor value must be carefully selected so that it will not trig cycle-by-cycle peak over current protection even for the worst condition such as higher input voltage, 50% duty cycle, lower inductance and lower switching frequency. Inductor Short, MOSFET Short Protection The bq24735 has a unique short circuit protection feature.
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bq24735 SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 www.ti.com Table 8. Component List for Typical System Circuit of Figure 1 (continued) PART DESIGNATOR QTY DESCRIPTION R14 1 Resistor, Chip, 10Ω, 1/10W, 5%, 0603 R15 1 Resistor, Chip, 7.5Ω, 1/10W, 5%, 0603 RAC, RSR 2 Resistor, Chip, 0.
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bq24735 www.ti.com SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 APPLICATION INFORMATION Negative Output Voltage Protection Reversely insert the battery pack into the charger output during production or hard shorts on battery to ground will generate negative output voltage on SRP and SRN pin.
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bq24735 SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 www.ti.com The bq24735 has charge under current protection (UCP) by monitoring charging current sensing resistor cycleby-cycle. The typical cycle-by-cycle UCP threshold is 5mV falling edge corresponding to 0.5A falling edge for a 10mΩ charging current sensing resistor. When the average charging current is less than 125mA for a 10mΩ charging current sensing resistor, the low side MOSFET is off until BTST capacitor voltage needs to refresh the charge.
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bq24735 www.ti.com Ptop = D ´ ICHG2 ´ RDS(on) + SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 1 ´ VIN ´ ICHG ´ (t on + t off ) ´ f s 2 (9) The first item represents the conduction loss. Usually MOSFET RDS(ON) increases by 50% with 100°C junction temperature rise. The second term represents the switching loss.
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bq24735 SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 www.ti.com D1 Adapter connector R2(1206) 10-20 Ω R1(2010) 2Ω VCC pin C1 2.2μF C2 0.47-1μF Figure 21. Input Filter bq24735 Design Guideline The bq24735 has a unique short circuit protection feature. Its cycle-by-cycle current monitoring feature is achieved through monitoring the voltage drop across RDS(on) of the MOSFETs after a certain amount of blanking time.
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bq24735 www.ti.com SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 To prevent unintentional charger shut down in normal operation, MOSFET RDS(on) selection and PCB layout is very important. Figure 23 shows a improvement PCB layout example and its equivalent circuit. In this layout, the system current path and charger input current path is not separated, as a result, the system current causes voltage drop in the PCB copper and is sensed by the IC.
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bq24735 SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 www.ti.com PCB Layout The switching node rise and fall times should be minimized for minimum switching loss. Proper layout of the components to minimize high frequency current path loop (see Figure 25) is important to prevent electrical and magnetic field radiation and high frequency resonant problems. Here is a PCB layout priority list for proper layout. Layout PCB according to this specific order is essential. 1.
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bq24735 www.ti.com SLUSAK9A – SEPTEMBER 2011 – REVISED JANUARY 2013 Charge Current Direction R SNS To Inductor To Capacitor and battery Current Sensing Direction To SRP and SRN pin Figure 26. Sensing resistor PCB layout. SPACER REVISION HISTORY Changes from Original (September 2011) to Revision A Page • Added ESD ratings to the ABSOLUTE MAXIMUM RATINGS .............................................................................................
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE MATERIALS INFORMATION www.ti.com 25-Feb-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant BQ24735RGRR VQFN RGR 20 3000 330.0 12.4 3.75 3.75 1.15 8.0 12.0 Q1 BQ24735RGRT VQFN RGR 20 250 180.0 12.4 3.75 3.75 1.15 8.0 12.
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PACKAGE MATERIALS INFORMATION www.ti.com 25-Feb-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) BQ24735RGRR VQFN RGR 20 3000 552.0 367.0 36.0 BQ24735RGRT VQFN RGR 20 250 552.0 185.0 36.
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