Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsPMICsPMIC - battery management Charge management Multi-Chemistry VQFN 28 (5x5) Surface-mount

EAO

ICREF

EAI

FBO

VDDP

LGATE

PGND

CSOP

CSON

bq24745

28LDQFN

TOP VIEW

ACIN

VREF

VFB

27 26 25 24

8 149 10 11 12 13

VICM

SDA

SCL

VDDSMB

GND

ACOK

CSSP

CSSN

ICOUT

BOOT

UGAT

PHAS

DCIN

bq24745

www.ti.com

SLUS761D –DECEMBER 2007– REVISED OCTOBER 2011

SMBus-Controlled Multi-Chemistry Battery Charger With Input

Current Detect Comparator and Charge Enable Pin

Check for Samples: bq24745

FEATURES

• < 1-mA Input DCIN Current With Adapter

Present and Charge Disabled

• NMOS-NMOS Synchronous Buck Converter

• 28-Pin, 5-mm × 5-mm QFN Package

with 300-kHz Frequency and >95% Efficiency

• 30-ns Minimum Driver Dead-Time and 99.5%

APPLICATIONS

Maximum Effective Duty Cycle

• Notebook and Ultra-Mobile Computers

• High-Accuracy Voltage and Current Regulation

• Portable Data-Capture Terminals

– ±0.5% Charge Voltage Accuracy

• Portable Printers

– ±3% Charge Current Accuracy

• Medical Diagnostics Equipment

– ±3% Adapter Current Accuracy

• Battery Bay Chargers

– ±2% Input Current Sense Amp Accuracy

• Battery Backup Systems

• Integration

– Input Current Comparator, With Adjustable

DESCRIPTION

Threshold and Hysteresis

The bq24745 is a high-efficiency, synchronous

– Internal Soft-Start

battery charger with an integrated input-current

• Safety

comparator, offering low component count for

space-constrained, multi-chemistry battery-charging

– Dynamic Power Management (DPM)

applications. The input-current, charge-current, and

• Up to 19.2-V Battery Voltage

charge-voltage DACs allow very high regulation

• 7-V–24-V AC/DC-Adapter Operating Range

accuracies that can be easily programmed by the

system power-management microcontroller using the

• Simplified SMBus Control Interface

SMBus interface. The bq24745 charges two, three, or

– Charge Voltage DAC (1.024 V–19.2 V)

four series Li+ cells, and is available in a 28-pin,

– Charge Current DAC (128 mA–8.064 A)

5-mm × 5 mm QFN package.

– Adapter Current Limit DPM DAC (256

mA–11.008 A)

• Status and Monitoring Outputs

– AC/DC Adapter Present With Adjustable

Voltage Threshold

– Input Current Comparator With Adjustable

Threshold and Hysteresis

– Current Sense Amplifier for Current Drawn

From Input Source

• Charge Any Battery Chemistry: Li+, NiCd,

NiMH, Lead Acid, Etc.

• Charge Enable Pin

• < 10-μA Battery Current With Adapter

Removed

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.

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 (39 pages)

PAGE 1
bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 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. DESCRIPTION (CONTINUED) The bq24745 features dynamic power management (DPM) and input power limiting.
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.com VIN = 20 V, VBAT = 4-cell Li-Ion, ICHARGE = 4.5 A, VICMer_limit = 6 A, for ICOUT Input Current comparator. Q1 (ACFET) Q2 (RBFET) SI4435 SI4435 ADAPTER + CHRG_IN RC1 P 2.2Ω ADAPTER - RC6 10Ω C1 2.2u P Controlled by HOST C2 C6 1uF R1 464k 1% RAC 0.010 0.1uF C15 10uF C14 10uF C3 0.1uF 27 CSSN 28 CSSP 22 DCIN ACIN bq24745 +3.
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.com Table 1. PIN FUNCTIONS – 28-PIN QFN PIN NO. 4 FUNCTION NAME 1 ICREF Input-current comparator voltage reference input. Connect a resistor divider from VREF to ICREF and from ICREF to GND to program the reference for the ICOUT comparator. The ICREF pin voltage is compared to the VICM pin voltage and the logic output is given on the ICOUT open-drain pin.
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.com Table 1. PIN FUNCTIONS – 28-PIN QFN (continued) PIN NO. FUNCTION NAME 25 BOOT PWM high-side driver positive supply. Connect a 0.1-μF bootstrap ceramic capacitor from BOOT to PHASE. Connect a small bootstrap Schottky diode from VDDP to BOOT. 26 ICOUT Input-current comparator active-high open-drain logic output. Place a 10-kΩ pullup resistor from the ICOUT pin to the pullup voltage rail.
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.com ELECTRICAL CHARACTERISTICS 7 V ≤ VDCIN ≤ 24 V, 0°C < TJ < 125°C, typical values are at TA = 25°C, with respect to AGND (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT OPERATING CONDITIONS VDCIN_OP DCIN input-voltage operating range 7 24 V DCIN V 16.884 V CHARGE VOLTAGE REGULATION VVFB_OP VFB input-voltage range 0 16.716 ChargeVoltage() = 0x41A0 –0.5% 12.
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.com ELECTRICAL CHARACTERISTICS (continued) 7 V ≤ VDCIN ≤ 24 V, 0°C < TJ < 125°C, typical values are at TA = 25°C, with respect to AGND (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT ADAPTER CURRENT SENSE AMPLIFIER VCSSP/N_OP Input common-mode range 0 24 VVICM VICM output-voltage range Voltage on CSSP/CSSN 0 2.
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.com ELECTRICAL CHARACTERISTICS (continued) 7 V ≤ VDCIN ≤ 24 V, 0°C < TJ < 125°C, typical values are at TA = 25°C, with respect to AGND (unless otherwise noted) PARAMETER IVDDSMB_Iq VDDSMB quiescent current TEST CONDITIONS MIN VVDDSMB = SCL = SDA = 5.
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.com Figure 3. SMBus Communication Timing Waveforms TYPICAL CHARACTERISTICS VREF LOAD AND LINE REGULATION vs LOAD CURRENT VDDP LOAD AND LINE REGULATION vs LOAD CURRENT 0 0.40 0.20 VDDP - Error - % VREF - Error - % 0 -0.20 DCIN = 20 V -0.40 DCIN = 10 V -1 DCIN = 10 V -2 -0.60 DCIN = 20 V -0.80 -1 0 5 10 15 20 25 30 35 40 -3 0 IL - Load Current - mA Figure 4. 10 20 40 60 IL - Load Current - mA 80 100 Figure 5.
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.com TYPICAL CHARACTERISTICS (continued) VFB (BATTERY) VOLTAGE REGULATION ACCURACY vs CHARGE CURRENT VFB (BATTERY) VOLTAGE REGULATION ACCURACY vs DAC VBAT SETPOINT 1 1.2 DCIN = 20 V Battery Voltage Regulation Accuracy - % Battery Voltage Accuracy - % 3 CELL @ 12.592 V, ICHG @ 8.064 A, DCIN = 20 V 0 -1 -2 -3 0 1 2 3 4 5 6 Battery Charge Current - A 7 8 1 0.8 0.6 0.4 0.2 0 -0.
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.com TYPICAL CHARACTERISTICS (continued) INPUT CURRENT REGULATION (DPM) ACCURACY vs DAC IDPM SETPOINT VICM INPUT CURRENT-SENSE AMPLIFIER ACCURACY INPUT CHARGE CURRENT 0 0 DCIN = 20 V, VFB = 9 V -0.2 Input Current Regulation Accuracy - % -0.5 -0.4 VICM Accuracy - % -0.6 -1 -1.5 -2 VFB = 9 V, DCIN = 20 V -0.8 -1 -1.2 -1.4 -1.6 -2.5 -1.
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.com TYPICAL CHARACTERISTICS (continued) INPUT CURRENT REGULATION (DPM) TRANSIENT SYSTEM LOAD RESPONSE CCM TO DCM CHARGE CURRENT REGULATION ACCURACY VFB (BATTERY) VOLTAGE Ch1 2 A/div 0.5 I(DCIN) Ch3 2 A/div Ch4 500 mV/div I(SYS) VICM Battery Charge Current Accuracy - % Ch2 5 A/div 0 ILOAD -0.5 -1 -1.5 -2 -2.5 t − Time = 1 ms/div 3-Cell at 12.592 V, ICHG at 4.
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.com TYPICAL CHARACTERISTICS (continued) SOFT-START, INDUCTOR CURRENT AND CHARGE CURRENT Ch4 1 A/div Ch3 1 V/div CE I(IND) Ch1 1 A/div ILOAD Ch4 5 V/div PH VDDP t − Time = 1 ms/div Figure 20. Figure 21. CHARGE ENABLED BY SMBus CHARGE DISABLED BY SMBus Ch1 2 V/div Ch4 5 V/div PH VDDP VDDP t − Time = 10 ms/div Figure 22. Figure 23.
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.com TYPICAL CHARACTERISTICS (continued) BATTERY SHORTED CHARGER RESPONSE, OVERCURRENT PROTECTION (OCP) AND CHARGE CURRENT REGULATION UGATE Ch3 2 A/div PHASE Ch2 10 V/div Ch2 10 V/div Ch1 10 V/div NEAR 100% DUTY CYCLE BOOTSTRAP RECHARGE PULSE Ch3 2 A/div Ch4 5 V/div I(IND) VFB I(IND) LGATE t − Time = 400 ms/div Figure 27.
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.com TYPICAL CHARACTERISTICS (continued) Ch2 5 V/div PROGRAMMABLE REFERENCE AND HYSTERESIS INPUT CURRENT COMPARATOR (With Pulsed Current) ICOUT Ch3 100 mV/div Ch4 1 V/div ICREF IIN VICM t − Time = 4 ms/div Figure 32.
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.com FUNCTIONAL BLOCK DIAGRAM 0.6V WAKEUP - ENA ACOK ACOK + 2.4V + - ACIN 3.
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.com DETAILED DESCRIPTION SMBus Interface The bq24745 operates as a slave, receiving control inputs from the embedded controller host through the SMBus interface. Battery-Charger Commands The bq24745 supports five battery-charger commands that use either Write-Word or Read-Word protocols, as summarized in Table 2. ManufacturerID() and DeviceID() can be used to identify the bq24745.
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 A tLOW tHIGH B C www.ti.com D E F G H I J K SMBCLK SMBDATA A = START CONDITION B = MSB OF ADDRESS CLOCKED INTO SLAVE C = LSB OF ADDRESS C LOCKED INTO SLAVE D = R/W BIT CLOCKED INTO SLAVE E = SLAVE PULLS SMBDATA LINE LOW F = ACKNOWLEDGE BIT CLOCKED INTO MASTER G = MSB OF DATA CLOCKED INTO MASTER H = LSB OF DATA CLOCKED INTO MASTER I = ACKNOWLEDGE CLOCK PULSE J = STOP CONDITION K = NEW START CONDITION Figure 35.
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.com Table 3.
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.com Table 4. Charge Current Register (0x14), Using 10-mΩ Sense Resistor (continued) BIT BIT NAME DESCRIPTION 12 Charge current, DACI 5 0 = Adds 0 mA of charger current 1 = Adds 4,096 mA of charger current 13 – Not used 14 – Not used 15 – Not used INPUT ADAPTER CURRENT REGULATION The total input current from an ac adapter or other dc source is a function of the system supply current and the battery charging current.
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.com Table 5. Input Current Register (0x3F), Using 10-mΩ Sense Resistor. (continued) BIT BIT NAME DESCRIPTION 12 Charge current, DACS 5 0 = Adds 0 mA of charger current 1 = Adds 8,192 mA of charger current; 11,008 mA max 13 – Not used 14 – Not used 15 – Not used ADAPTER DETECT AND POWER UP An external resistor voltage divider attenuates the adapter voltage before it goes to ACIN.
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.com CONVERTER OPERATION The synchronous buck PWM converter uses a fixe- frequency (300 kHz) voltage mode with feed-forward control scheme. A type-III compensation network allows using ceramic capacitors at the output of the converter. The compensation input stage is connected between the feedback output (FBO) and the error amplifier input (EAI).
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.com REFRESH BTST CAPACITOR If the BOOT pin to PHASE pin voltage falls below 4 V for more than three cycles, then the high-side n-channel power MOSFET is turned off and the low-side n-channel power MOSFET is turned on for 40 ns to pull the PHASE node down and recharge the BOOT capacitor.
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.com HIGH-ACCURACY VICM USING CURRENT-SENSE AMPLIFIER (CSA) An industry standard, high-accuracy current-sense amplifier (CSA) is used to monitor the input current by the host or some discrete logic through the analog voltage output of the VICM pin. The CSA amplifies the input sensed voltage of CSSP-CSSN by 20× through the VICM pin. The VICM output is a voltage source 20 times the input differential voltage. Once DCIN is above 4.
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.com ACIN ACOK Comparator ACOK + 2.4V CSSP 1k CSSN ACOK VICM Current Sense Amplifier + - VICM Error Amplifier Disable 20k + VICM VICM Disable Program Hysteresis of comparator by putting a resistor in feedback from ICOUT pin to ICREF pin. Input Current Comparator ICREF + - ICOUT Figure 36.
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.com REMOTE SENSE The bq24745 has a dedicated remote sense pin, VFB, which allows the rejection of board resistance and selector resistance. To use remote sensing fully, connect VFB directly to the battery interface through an unshared battery-sense Kelvin trace, and place a 0.1-μF ceramic capacitor near the VFB pin to GND (see Figure 1). Remote Kelvin sensing provides higher regulation accuracy by eliminating parasitic voltage drops.
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.com GLOSSARY VICM Output Voltage of Input Current Monitor ICREF DPM Input Current Reference - sets the threshold for the input current limit Dynamic Power Management CSOP, CSON Current Sense Output of battery positive and negative These pins are used with an external low-value series resistor to monitor the current to and from the battery pack.
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.com REVISION HISTORY NOTE: Page numbers of previous versions may differ from the current version. Changes from Original (December 2007) to Revision A Page • Changed The data sheet title From: SMBus-Controlled Multi-Chemistry Battery Charger With Input Current Detect Comparator To: SMBus-Controlled Multi-Chemistry Battery Charger With Input Current Detect Comparator and Charge Enable Pin ......................................................
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bq24745 SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011 www.ti.com • Changed "R11" to "R21" in Component List ....................................................................................................................... 28 • Added R22 to Component List ............................................................................................................................................
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE MATERIALS INFORMATION www.ti.com 26-Jan-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 BQ24745RHDR VQFN RHD 28 3000 330.0 12.4 5.3 5.3 1.5 8.0 12.0 Q2 BQ24745RHDT VQFN RHD 28 250 180.0 12.4 5.3 5.3 1.5 8.0 12.
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PACKAGE MATERIALS INFORMATION www.ti.com 26-Jan-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) BQ24745RHDR VQFN RHD 28 3000 367.0 367.0 35.0 BQ24745RHDT VQFN RHD 28 250 210.0 185.0 35.
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IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.