SLUS553D − MAY 2003 − REVISED JULY 2005 FEATURES D Dynamic Power Management, DPM 6 19 7 18 8 17 9 16 10 15 11 14 12 13 ACSET VREF ENABLE BATSET COMP 3 4 5 6 7 ACPRES 27 9 ACP ACDET 26 10 NC ACDRV 25 11 NC BATDRV 24 12 BATP NC 23 13 IBAT VCC 22 14 NC NC − No internal connection SRN 20 ACN 15 5 8 16 21 28 SRP 4 ACSEL 17 22 GND 3 ACDRV BATDRV VCC PWM VHSP ALARM VS GND SRP SRN IBAT BATP 18 23 VS 24 2 19 1 ALARM ACDET ACPRES ACSEL BATDEP SRSET ACSET VREF ENABLE BATSET COMP ACN ACP bq24703 RHD PACKAGE (BOTTOM VIEW) SRSET bq24702, bq24703 PW PACKAGE (TOP VIEW) 2 D 20 D VHSP D The bq24702/bq24703 uses a fixed frequency, pulse width modulator (PWM) to accurately control battery charge current and voltage. Charge current limits can be programmed from a keyboard controller DAC or by external resistor dividers from the precision 5-V, ±0.6%, externally bypassed voltage reference (VREF), supplied by the bq24702/bq24703. BATDEP D D 1 D The bq24702/bq24703 uses dynamic power management (DPM) to minimize battery charge time by maximizing use of available wall-adapter power. This is achieved by dynamically adjusting the battery charge current based on the total system (adapter) current. 21 D D The bq24702/bq24703 is a highly integrated battery charge controller and selector tailored for notebook and sub-notebook PC applications. Minimizes Battery Charge Time Integrated Selector Supports Battery Conditioning and Smart Battery Learn Cycle Zero Volt Operation Selector Feedback Circuit Ensures Break-Before-Make Transition ±0.4% Charge Voltage Accuracy, Suitable for Charging Li-Ion Cells ±4% Charge Current Accuracy 300-kHz Integrated PWM Controller for High-Efficiency Buck Regulation Depleted Battery Detection and Indication to Protect Battery From Over Discharge 20-µA Sleep Mode Current for Low Battery Drain 24-Pin TSSOP Package and 5 mm × 5 mm QFN package (bq24703 only) PWM D DESCRIPTION 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. !"#$ % &'!!($ #% )'*&#$ +#$(, !+'&$% &!" $ %)(&&#$% )(! $-( $(!"% (.#% %$!'"($% %$#+#!+ /#!!#$0, !+'&$ )!&(%%1 +(% $ (&(%%#!*0 &*'+( $(%$1 #** )#!#"($(!%, Copyright 2003 − 2004, Texas Instruments Incorporated www.ti.com 1 SLUS553D − MAY 2003 − REVISED JULY 2005 DESCRIPTION (continued) The battery voltage limit can be programmed by using the internal 1.196-V, ±0.5% precision reference, making it suitable for the critical charging demands of lithium-ion cells. Also, the bq24702/bq24703 provides an option to override the precision reference and drive the error amplifier either directly from an external reference or from a resistor divider off the 5 V supplied by the integrated circuit. The selector function allows the manual selection of the system power source, battery or wall-adapter power. The bq24702/bq24703 supports battery-conditioning and battery-learn cycles through the ACSEL function. The ACSEL function allows manual selection of the battery or wall power as the main system power. It also provides autonomous switching to the remaining source (battery or ac power) should the selected system power source terminate (refer to Table 1 for the differences between the bq24702 and the bq24703). The bq24702/bq24703 also provides an alarm function to indicate a depleted battery condition. The bq24702/bq24703 PWM controller is ideally suited for operation in a buck converter for applications when the wall-adapter voltage is greater than the battery voltage. DISSIPATION RATINGS MAXIMUM POWER DISSIPATION (LOW K BOARD) vs FREE-AIR TEMPERATURE 1.60 Maximum Power Dissipation (Low K Board) − W Maximum Power Dissipation (High K Board) − W MAXIMUM POWER DISSIPATION (HIGH K BOARD) vs FREE-AIR TEMPERATURE MAX Pd (W) @ 500 LFM 1.40 MAX Pd (W) @ 250 LFM 1.20 MAX Pd (W) @ 150 LFM MAX Pd (W) @ 0 LFM 1 0.80 0.60 0.40 θJA = 89.37 C/W @ 0 LFM, θJA = 77.98 C/W @ 150 LFM, θJA = 73.93 C/W @ 250 LFM, θJA = 68.23 C/W @ 500 LFM 0.20 1.40 1.20 MAX Pd (W) @ 500 LFM MAX Pd (W) @ 250 LFM 1 MAX Pd (W) @ 150 LFM MAX Pd (W) @ 0 LFM 0.80 0.60 0.40 θJA = 150.17 C/W @ 0 LFM, θJA = 110.95 C/W @ 150 LFM, θJA = 99.81 C/W @ 250 LFM, θJA = 86.03 C/W @ 500 LFM 0.20 0 0 25 50 70 TA − Free-Air Temperature − °C 85 25 50 70 85 TA − Free-Air Temperature − °C † The JEDEC low K (1s) board design used to derive this data was a 3-inch x 3-inch, two layer board with 2 ounce copper traces on top of the board. ‡ The JEDEC high K (1s) board design used to derive this data was a 3-inch x 3-inch, multilayer board with 1 ounce internal power and ground planes and 2 ounce copper traces on top and bottom of the board. 2 www.ti.com SLUS553D − MAY 2003 − REVISED JULY 2005 Table 1. Available Options CONDITION −20°C ≤ TJ ≤ 125°C SELECTOR OPERATION bq24702PW bq24703RHD Battery as Power Source Battery removal Automatically selects ac + alarm Automatically selects ac + alarm Battery reinserted Selection based on selector inputs Adapter latched until adapter is removed or ac select toggles. AC removal Automatically selects battery Automatically selects battery AC reinserted Selection based on selector inputs Selection based on selector inputs Battery as power source Sends ALARM signal Automatically selects ac Sends ALARM signal AC as power source Sends ALARM signal Sends ALARM signal Depleted battery condition Depleted battery condition AC as Power Source Depleted Battery Condition ALARM Signal Active When selector input is not equal to selector output (single pulse alarm) ABSOLUTE MAXIMUM RATINGS OVER OPERATING FREE-AIR TEMPERATURE (unless otherwise noted)Ĕ} Supply voltage range: VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −0.3 V to 30 V Battery voltage range: SRP, SRN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −0.3 V to 30 V Input voltage: ACN, ACP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −0.3 V to 30 V Virtual junction temperature range, TJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −40°C to 125°C Maximum source/sink current VHSP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 mA Maximum ramp rate for VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 V/ µs Maximum sink current ACPRES, COMP, ALARM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5 mA Maximum ramp rate for V(BAT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 V/ µs Maximum source/sink current BATDRV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 mA Maximum source/sink current ACDRV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 mA Maximum source/sink current PWM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 mA Maximum source/sink current pulsed ACDRV, (10-µs rise time, 10-µs fall time, 1-ms pulse width, single pulse) 50 mA Maximum source current VREF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 mA Maximum source current SRP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 mA Maximum difference voltage SRP − SRN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 V Storage temperature range Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −65°C to 150°C Lead temperature (soldering, 10 seconds) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300°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 under “recommended operating conditions” is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. ‡ All voltages are with respect to ground. Currents are positive into and negative out of the specified terminals. Consult the Packaging section of the data book for thermal limitations and considerations of the package. www.ti.com 3 SLUS553D − MAY 2003 − REVISED JULY 2005 RECOMMENDED OPERATING CONDITIONS (TA = TOPR) all voltages relative to Vss MIN MAX Analog and PWM operation 7.0 28 Selector operation 4.5 28 Negative ac current sense, (ACN) 7.0 28 V Positive ac current sense, (ACP) 7.0 28 V Negative battery current sense, (SRN) 5 28 V Positive battery current sense, (SRP) 5 28 V AC or adapter power detection (ACDET) 0 5 V AC power indicator (ACPRES) 0 5 V AC adapter power select (ACSEL) 0 5 V Depleted battery level (BATDEP) 0 5 V Battery charge current programming voltage (SRSET) 0 2.5 V Charge enable (ENABLE) 0 5 V External override to an internal 0.5% precision reference (BATSET) 0 2.5 V Inverting input to the PWM comparator (COMP) 0 5 V Battery charge regulation voltage measurement input to the battery—voltage gm amplifier (BATP) 0 5 V Battery current differential amplifier output (IBAT) 0 5 V System load voltage input pin (VS) 0 2.5 V Depleted battery alarm output (ALARM) 0 5 V VHSP VCC V Supply voltage, (VCC) Gate drive output (PWM) Battery power source select output (BATDRV) AC or adapter power source selection output (ACDRV) ACSET Operating free-air temperature, TA 4 www.ti.com UNIT V 0 28 V VHSP VCC V 0 2.5 V −40 85 °C SLUS553D − MAY 2003 − REVISED JULY 2005 ELECTRICAL CHARACTERISTICS (−40°C ≤ TJ ≤ 125°C, 7.0 VDC ≤ VCC ≤ 28 VDC, all voltages relative to Vss) (unless otherwise specified) Quiescent Current PARAMETER IDD(OP) IDD(SLEEP) TEST CONDITIONS Total chip operating current ACPRES = High, EN = 0 Total battery sleep current, ac not present ACPRES = Low MIN TYP MAX UNIT 1 1.6 6 mA 22 28 µA logic interface dc characteristics PARAMETER VOL VIL Low-level output voltage (ACPRES, ALARM) VIH I(SINK1) High-level input voltage (ACSEL, ENABLE) I(SINK2) Sink current (ALARM) TEST CONDITIONS MIN TYP IOL = 1 mA Low-level input voltage (ACSEL, ENABLE) Sink current (ACPRES) MAX 0.4 V 0.6 V 1.8 VOL = 0.4 VOL = 0.4 UNIT V 1.5 2 2.5 mA 1.5 2 2.5 mA PWM Oscillator PARAMETER fOSC(PWM) Oscillator frequency MIN TYP MAX 0°C ≤ TJ ≤ 85°C TEST CONDITIONS 260 300 340 −40°C ≤ TJ ≤ 125°C 240 300 350 Maximum duty cycle 3.8 V Minimum duty cycle 0% Input voltage for minimum dc (COMP) Oscillator ramp voltage (peak-to-peak) VIK(COMP) Internal input clamp voltage (tracks COMP voltage for maximum dc) IS(COMP) Internal source current (COMP) kHz 100% Input voltage for maximum dc (COMP) V(RAMP) UNIT 0.8 1.85 Error amplifier = OFF, V(COMP) = 1 V 2.15 2.30 3.8 4.5 70 110 140 µA MIN TYP MAX UNIT V Leakage Current PARAMETER TEST CONDITIONS V(ACDET) = 5 V V(SRSET) = 2.5 V 0.2 µA 0.2 µA V(ACSET) = 2.5 V V(BATDEP) = 5 V 0.2 µA 0.2 µA V(VS) = 5 V V(ALARM) = 5 V 0.2 µA 0.2 µA V(ACSEL) = 5 V V(ENABLE) = 5 V 0.2 µA 0.2 µA V(ACPRES) = 5 V V(BATP) = 5 V 0.2 µA Leakage current, BATP 0.2 µA Leakage current, BATSET V(BATSET) = 2.5 V 0.2 µA IL(ACDET) IL(SRSET) Leakage current, ACDET IL(ACSET) IL(BATDEP) Leakage current, ACSET IL(VS) IL(ALARM) Leakage current, VS IL(ACSEL) IL(ENABLE) Leakage current, ACSEL IL(ACPRES) IL(BATP) Leakage current, ACPRES IL(BATSET) Leakage current, SRSET Leakage current, BATDEP Leakage current, ALARM Leakage current, ENABLE www.ti.com 5 SLUS553D − MAY 2003 − REVISED JULY 2005 ELECTRICAL CHARACTERISTICS (CONTINUED) (−40°C ≤ TJ ≤ 125°C, 7.0 VDC ≤ VCC ≤ 28 VDC, all voltages relative to Vss) (unless otherwise specified) Battery Current-Sense Amplifier PARAMETER gm CMRR TEST CONDITIONS Transconductance gain MIN TYP MAX UNIT 75 120 175 mA/V Common-mode rejection ratio See Note 1 VICR Common-mode input (SRP, SRN) voltage range VCC = SRN, SRP + 2 V I(SINK) Sink current (COMP) COMP = 1 V, (SRP − SRN) = 10 mV 0.5 Input bias current (SRP), See Note 2 V(SRP) = 16 V, (SRP − SRN) = 100 mV SRSET = 2.5 V, VCC = 28 Input bias current accuracy (ISRP − ISRN) (SRP − SRN) = 100 mV, SRSET= 2.5 V, VCC = 28 V, 0 ≤ TJ ≤ 125°C IIB V(SET) Battery current programming voltage (SRSET) AV Battery current set gain 90 5 30 V 1.5 2.5 mA 70 85 110 −3 0 3 µA A 0 0.65 V ≤ SRSET ≤ 2.5 V, 8 V ≤ SRN ≤ 16 V, See Note 3 dB 24 25 2.5 V 26 V/V Total battery current-sense mid-scale accuracy SRSET = 1.25 V, TJ = 25°C, See Note 4 −5% 5% SRSET = 1.25 V, See Note 4 −6% 6% Total battery current-sense full-scale accuracy SRSET = 2.5 V, TJ = 25°C, See Note 4 −3% 3% SRSET = 2.5 V, See Note 4 −4% 4% NOTES: 1. Specified by design. Not production tested. 2 I(SRP) = I(SRN) = (V(SRSET) / 50 kΩ) + ((V(SRP) − V(SRN) / 3 kΩ) example: If (V(SRSET) = 2.5 V) , (V(SRP) − V(SRN) = 100 mV) Then I(SRP) = I(SRN) = 83 µA 1 3. I + SRSET BAT A R V SENSE 4. Total battery-current set is based on the measured value of (SRP−SRN) = ∆m, and the calculated value of (SRP−SRN) = ∆C, using (Dm * Dc) the measured gain, AV. Dc + SRSET , Total accuracy in % + 100, I (SRP) * I (SRN) + 0 Dc A V 6 www.ti.com SLUS553D − MAY 2003 − REVISED JULY 2005 ELECTRICAL CHARACTERISTICS (CONTINUED) (−40°C ≤ TJ ≤ 125°C, 7.0 VDC ≤ VCC ≤ 28 VDC, all voltages relative to Vss) (unless otherwise specified) Adapter Current-Sense Amplifier PARAMETER TEST CONDITIONS gm CMRR Transconductance gain VICR I(SINK) Common-mode input voltage range (ACP) IIB Common-mode rejection ratio MIN TYP MAX UNIT 75 130 175 mA/V See Note 1 90 dB Sink current (COMP) COMP = 1 V, (ACP − ACN) = 10 mV 7.0 0.5 1.5 VCC 2.5 Input bias current (ACP, ACN) ACP = ACN = 28 V, VCC = 28 V, ACSET = 2.5 V 40 50 65 Input bias current accuracy ratio (I(ACP), I(ACN)) ACP = ACN = 28 V, VCC = 28 V, ACSET = 2.5 V, 0 ≤ TJ ≤ 125°C −3 0 3 A µA V(SET) AC current programming voltage (ACSET) AV AC current set gain 0.65 V ≤ ACSET ≤ 2.5 V, 12 V ≤ ACP ≤ 20 V, See Note 5 ACSET = 1.25 V, TJ = 25°C, See Note 6 ACSET = 1.25 V, See Note 6 −5% Total ac current-sense mid-scale accuracy −6% 6% ACSET = 2.5 V, TJ = 25°C, See Note 6 −3.5% 3.5% −4% 4% Total ac current-sense full-scale accuracy 0 ACSET = 2.5 V, See Note 6 V mA 24.5 25.3 2.5 V 26.5 V/V 5% Battery Voltage Error Amplifier PARAMETER TEST CONDITIONS gm CMRR Transconductance gain VICR VIT BATSET common-mode input voltage range I(SINK) Sink current COMP V(FB) NOTE: Common-mode rejection ratio MIN TYP MAX UNIT 75 135 175 mA/V See Note 1 Internal reference override input threshold voltage dB 2.5 V 0.20 0.25 0.35 V 0.5 1.5 2.5 mA TJ = 25°C TJ = 0°C to 85°C 1.190 1.196 1.202 1.183 1.196 1.203 TJ = −40°C to 125°C 1.178 1.196 1.204 COMP = 1 V, (BATP − BATSET) = 10 mV, BATSET = 1.25 V Error-amplifier precision reference voltage 90 1 V 1 + ACSET R A V SENSE 6. Total ac-current set accuracy is based on the measured value of (ACP−ACN) = ∆c, using the measured gain, AV. (Dm * Dc) Dc + ACSET , Total accuracy in % + 100, I (ACP) * I (ACN) + 0 Dc A V 5. Calculation of the ac current: I AC www.ti.com 7 SLUS553D − MAY 2003 − REVISED JULY 2005 ELECTRICAL CHARACTERISTICS (CONTINUED) (−40°C ≤ TJ ≤ 125°C, 7.0 VDC ≤ VCC ≤ 28 VDC, all voltages relative to Vss) (unless otherwise specified) Battery Current Output Amplifier PARAMETER TEST CONDITIONS MIN TYP MAX UNIT G(TR) Transfer gain (SRP − SRN) = 5 mV, See Note 7 20 V/V VI(BAT) Battery current readback output voltage (IBAT) (SRP − SRN) = 5 mV, SRP = 12 V, VCC = 18 V, TJ = 25°C 100 mV Line rejection voltage TJ = 25°C 10 mV/V CM Common-mode input range (SRP) 5 28 V VO(IBAT) Battery current output voltage range (IBAT) 0 2.5 V IS(O) Output source current (IBAT) 9.4 mA (SRP − SRN) = 100 mV 5 (SRP − SRN) = 50 mV, TJ = 25°C, See Note 7 Total battery current readback full-scale accuracy 7.1 −3% 2.4% (SRP − SRN) = 50 mV, 0°C ≤ TJ ≤ 85°C −20% 20% (SRP − SRN) = 100 mV, TJ = 25°C, See Note 7 −1.5% 1.2% −6% 8.5% (SRP − SRN) = 100 mV, 0°C < TJ < 85°C 5-V Voltage Reference PARAMETER Vref Output voltage (VREF) Line regulation Load regulation TEST CONDITIONS MIN TYP MAX TJ = 25°C TJ = 0°C to 85°C 4.985 5 5.013 4.946 5 5.013 TJ = 40°C to 85°C TJ = −40°C to 125°C 4.946 5 5.03 5 5.03 V 0.1 0.37 mV/V 4.926 ILOAD = 5 mA 1 mA ≤ ILOAD ≤ 5 mA Output capacitor equivalent resistor ESR V 4 mV/mA 20 30 mA 2.2 10 µF 5 1000 mΩ 8 Capacitance V 1.1 Short circuit current 5V REF output capacitor UNIT Half Supply Regulator PARAMETER V(HSP) NOTE: 8 TEST CONDITIONS I(SINK) = 20 mA, VCC = 18 V I(SINK) = 1 mA, VCC = 7 V V IBAT 7. Battery readback transfer gain G + TR (SRP * SRN) Voltage regulation www.ti.com MIN VCC − 11 TYP VCC − 10.2 MAX VCC − 8.5 1.5 UNIT V SLUS553D − MAY 2003 − REVISED JULY 2005 ELECTRICAL CHARACTERISTICS (CONTINUED) (−40°C ≤ TJ ≤ 125°C, 7.0 VDC ≤ VCC ≤ 28 VDC, all voltages relative to Vss) (unless otherwise specified) MOSFET Gate Drive PARAMETER AC driver RDS(on) high AC driver RDS(on) low TEST CONDITIONS MIN TYP VCC = 18 V, I(ACDRV) = 1 mA VCC = 18 V, I(ACDRV) = 1 mA MAX UNIT 85 150 Ω 55 110 Ω VCC = 18 V, I(BATDRV) = 1 mA VCC = 18 V, I(BATDRV) = 1 mA 315 600 Ω Battery driver RDS(on) low 70 115 Ω tda Time delay from ac driver off to battery driver on ACSEL 2.4 V ⇓ 0.2 V 1.2 2 µs tdb Time delay from battery driver off to ac driver on ACSEL 0.2 V ⇑ 2.4 V 2.4 3.3 µs VOH PWM driver high-level output voltage IO = −10 mA, VCC = 18 V IO = −50 mA, VCC = 18 V Battery driver RDS(on) high VCC −0.18 VCC −1.2 VCC −0.09 VCC −0.8 7 14 Ω VHSP+0.1 VHSP+0.6 VHSP+0.4 VHSP+1.2 V 5 8.5 Ω UNIT PWM driver RDS(on) high VOL PWM driver low-level output voltage IO = 10 mA, VCC = 18 V IO = 50 mA, VCC = 18 V V PWM driver RDS(on) low Selector PARAMETER V(ACPRES) AC presence detect voltage VIT(ACPRES) td(ACPRES) AC presence hysteresis TEST CONDITIONS −40°C to 85°C MIN TYP MAX 1.194 1.246 1.286 1.208 1.246 1.285 V 1% Deglitch delay for adapter insertion µs 100 See Note 8 1.194 1.246 1.286 −40°C to 85°C 1.208 1.246 1.285 bq24702 only, See Note 8 0.869 1 1.144 −40°C to 85°C 0.880 1 1.118 1 2.5 3.5 µs µs V(BATDEP) Battery depletion ALARM trip voltage V(NOBAT) No battery detect, switch to ACDRV t(BATSEL) Battery select time (ACSEL low to BATDRV low) VS < BATP, 50% threshold, ACSEL 2.4 V ⇓ 0.2 V t(ACSEL) V(VS) AC select time (ACSEL high to ACDRV low) ACSEL 0.2 V ⇑ 2.4 V 1 2.5 3.5 VS voltage to enable BATDRV BATP = 1 V 0.98 1 1.02 VIT(VS) VS voltage hysteresis VS > BATP 20 35 85 MIN TYP MAX VCC = 7 V, TJ = 125°C, IO = 100 mA BATDEP increasing 5.3 8.7 0.743 0.794 0.840 BATDEP decreasing 0.570 0.62 0.656 V V V mV Zero Volt Operation PARAMETER rDS(on) Static drain source on-state resistance zero volt operation threshold TEST CONDITIONS UNIT Ω V NOTES: 8. Total battery current readback accuracy is based on the measured value of VIBAT, VIBATm, and the calculated value of VIBAT, VIBATc, using the measured value of the transfer gain, GTR. V *V IBATc 100 V + (SRP * SRN) GTR Total Accuracy in % + IBATm IBATc V IBATm 9. Refer to Table 1 to determine the logic operation of the bq24702 and the bq24703. www.ti.com 9 10 www.ti.com R10 Note1 Note 1: R8 Sets AC Adapter Current Limit R10 Sets Charge Current R12 Sets AC ADAPTER Current Limit R23 Sets the Battery Depleted Threshold R25 Sets the Charge Regulation Voltage R28 Sets System Break Before Make R19 = R21, Sets Zero Volt Charge Current C11 Optional, See Application Notes C12 For Value, See Application Notes C8 Value Depends on R21 and R19, See Application Notes D5, D6 Refer to the Application Section 17 GND 6 ACSET BATP 13 VS 18 BATDRV 23 9 BATSET BATSET 5 SRSET 2 ACPRES ACPRES PROCESSOR’S POWER SUPPLY COMP 10 SRN 15 4 8 ENABLE BATDEP 7 VREF 14 IBAT SRP 16 19 ALARM bq24702 bq24703 R2100 kΩ PWM 21 1 ACDET C10 180pF C7 4.7 µF 35 V C5 4.7 µF U3 SI4435DY Connect to GND to Disable C4 150pF R16 100 Ω C6 D3 13 V 1 µF 16V VHSP 20 VCC 22 12 ACP 11 ACN 24 ACDRV D2 BAS16 ALARM R8 Note1 R18 10 Ω R29 30 kΩ C12 Note1 35V R15 100 Ω U2 SI4435DY 3 ACSEL C1 4.7 µ F C3 1 µF R13 100 Ω R14 0.025 ACSEL ENABLE C13 1 nF R12 Note1 R11 R6 100 kΩ Open IBAT AC Adapter D1 MBRD640CTT4 R28 Note1 D5 Note 1 R19 Note1 D4 MBRD640CTT4 L1 33 µH BAS16 R23 Note1 604 kΩ R27 R25 Note1 R24 604 kΩ C11 22 µ F Note1 35 V R22 604 kΩ R26 100K D9 D6 Note 1 C8 Note1 R21 Note1 R20 0.025 Ω U4 SI4435DY Battery Plus SYSTEM SLUS553D − MAY 2003 − REVISED JULY 2005 APPLICATION DIAGRAM SLUS553D − MAY 2003 − REVISED JULY 2005 BLOCK DIAGRAM VHSP VCC VREF 20 22 7 VREF ACPRES VHSP REGULATOR 2 VOLTAGE REFERENCE ACPRES ACPRES HYST ACDET 1 + VCC 300 kHz S Q R Q 2V VACPRES OSC PWM LOGIC HIGH−SIDE DRIVE LEVEL SHIFT 21 PWM 13 BATP + VHSP ACSEL 3 ENABLE 8 5V 100 µ A BATDA BATTERY VOLTAGE ERROR AMPLIFIER COMP + Zero Volt Charging VTBD 5V 10 ACP 12 ACN 11 ACSET 6 9 VCC 2kΩ + + + BATSET 0.25 V VFB ac CURRENT ERROR AMPLIFIER + SRN 2 kΩ + BATTERY CURRENT ERROR AMPLIFIER 25 kΩ 0.8 x VNOBAT VBATDEP BATDEP 4 DEPLETED BATTERY COMPARATOR BATP VS ALARM 18 19 15 SRN 5 SRSET 24 ACDRV 23 BATDRV 17 GND 14 IBAT VCC + 25 kΩ ADAPTER SELECT DRIVE VHSP 2 ACPRES ACSEL 1 ACDRV BATTERY SELECT DRIVE VCC SRP 1 bq24702 ONLY VCC BATTERY SELECT LOGIC AND ANTI−CROSS CONDUCT + SWITCH TO BATTERY SRP + NO BATTERY COMPARATOR + 16 ACSEL + A=20 SRN 2 bq24703 ONLY UDG−00137 www.ti.com 11 SLUS553D − MAY 2003 − REVISED JULY 2005 Terminal Functions TERMINAL 12 I/O DESCRIPTION bq24702 (PW) bq24703 (QFN) ACDET 1 26 I AC or adapter power detection ACDRV 24 25 O AC or adapter power source selection output ACN 11 8 I Negative differential input ACP 12 9 I Positive differential input ACPRES 2 27 O AC power indicator ACSEL 3 28 I AC adapter power select ACSET 6 3 I Adapter current programming voltage ALARM 19 19 O Alarm output BATDEP 4 1 I Depleted battery level BATDRV 23 24 O Battery power source select output BATP 13 12 I Battery charge regulation voltage measurement input to the battery-voltage gm amplifier BATSET 9 6 I External override to an internal precision reference COMP 10 7 O Inverting input to the PWM comparator ENABLE 8 5 I Charge enable GND 17 17 O Supply return and ground reference IBAT 14 13 O Battery current differential amplifier output PWM 21 21 O Gate drive output SRN 15 15 I Negative differential battery current sense amplifier input SRP 16 16 I/O Positive differential battery current sense amplifier input SRSET 5 2 I Battery charge current programming voltage VCC 22 22 I Operational supply voltage VHSP 20 20 O Voltage source to drive gates of the external MOSFETs NAME VREF 7 4 O Precision 5-V reference VS 18 18 I System (load) voltage input pin www.ti.com SLUS553D − MAY 2003 − REVISED JULY 2005 Pin Assignments ACDET: AC or adapter power detection. This input pin is used to determine the presence of the ac adapter. When the voltage level on the ACDET pin is less than VACPRES, the bq24702/bq24703 is in sleep mode, the PWM control is disabled, the BATDRV is driven low, and the ACDRV is driven high. This feature can be used to automatically select battery as the system power source. ACDRV: AC or adapter power source select output. This pin drives an external P-channel MOSFET used to switch to the ac wall-adapter as the system power source. When the ACSEL pin is high while the voltage on the ACDET pin is greater than VACPRES, the output ACDRV pin is driven low (VHSP). This pin is driven high (VCC) when the ACDET is less than VACPRES. ACN, ACP: Negative and positive differential inputs, respectively for ac-to-dc adapter current sense resistor. ACPRES: This open-drain output pin is used to indicate the presence of ac power. A logic high indicates there is a valid ac input. A low indicates the loss of ac power. ACPRES is high when the voltage level on the ACDET pin is greater than VACPRES. ACSEL: AC adapter power select. This input selects either the ac adapter or the battery as the power source. A logic high selects ac power, while a logic low selects the battery. ACSET: Adapter current programming voltage. This input sets the system current level at which dynamic power management occurs. Adapter currents above this programmed level activate the dynamic power management and proportionally reduce the available power to the battery. ALARM: Depleted battery alarm output. This open-drain pin indicates that a depleted battery condition exists. A pullup on ALARM goes high when the voltage on the BATDEP pin is below VACPRES. On the bq24702, the ALARM output also activates when the selector inputs do not match the selector state. BATDEP: Depleted battery level. A voltage divider network from the battery to BATDEP pin is used to set the battery voltage level at which depletion is indicated by the ALARM pin. See ALARM pin for more details. A battery depletion is detected when BATDEP is less than VACPRES. A no-battery condition is detected when the battery voltage is < 80% of the depleted threshold. In a no-battery condition, the bq24702 automatically selects ac as the input source. If ENABLE = 1, the PWM remains enabled. BATDRV: Battery power source select output. This pin drives an external P-channel MOSFET used to switch the battery as the system’s power source. When the voltage level on the ACDET pin is less than VACPRES, the output of the BATDRV pin is driven low, GND. This pin is driven high (VCC) when ACSEL is high and ACDET > VACPRES. BATP: Battery charge regulation voltage measurement input to the battery-voltage gm amplifier. The voltage on this pin is typically derived from a voltage divider network connected across the battery. In a voltage loop, BATP is regulated to the VFB precision reference of the battery voltage gm amplifier. BATSET: An external override to an internal precision reference. When BATSET is > 0.25 V, the voltage level on the BATSET pin sets the voltage charge level. When BATSET ≤ 0.25 V, an internal VFB reference is connected to the inverting input of the battery error amplifier. To ensure proper battery voltage regulation with BATSET, BATSET must be > 1.0 V. Simply ground BATSET to use the internal reference. COMP: The inverting input to the PWM comparator and output of the gm amplifiers. A type II compensation network between COMP and GND is recommended. ENABLE: Charge enable. A high on this input pin allows PWM control operation to enable charging while a low on this pin disables and forces the PWM output to a high state. Battery charging is initiated by asserting a logic 1 on the ENABLE pin. GND: Supply return and ground reference IBAT: Battery current differential amplifier output. The output of this pin produces a voltage proportional to the battery charge current. This voltage is suitable for driving an ADC input. www.ti.com 13 SLUS553D − MAY 2003 − REVISED JULY 2005 PWM: Gate drive output pin drives the P-channel MOSFET for PWM control. The PWM control is active when ACPRES, ACSEL, and ENABLE are high. PWM is driven low to VHSP and high to VCC. SRN, SRP: Differential amplifier inputs for battery current sense. These pins feed back the battery charge current for PWM control. SRN is tied to the battery terminal. SRP is the source pin for zero volt operation. SRSET: Battery charge current programmed voltage. The level on this pin sets the battery charge current limit. VCC: Operational supply voltage. VHSP: The VHSP pin is connected to a 1-µF capacitor (close to the pin) to provide a stable voltage source to drive the gates of the external MOSFETs. VHSP = VCC − 10 V for VCC > 10.5 V and VHSP = VCC − 0.5 V for VCC <10.5 V. A 13-V Zener diode should be placed between VCC and VHSP to prevent MOSFET overstress during start-up. VREF: Bypassed precision voltage 5-V output. It can be used to set fixed levels on the inverting inputs of any one of the three error amplifiers if desired. The tight tolerance is suitable for charging lithium-ion batteries. VS: System (Load) voltage input pin. The voltage on this pin indicates the system voltage in order to insure a break before make transition when changing from ac power to battery power. The battery is protected from an over-voltage condition by disabling the P-channel MOSFET connected to the BATDRV pin if the voltage at VS is greater than BATP. This function can be eliminated by grounding the VS pin. 14 www.ti.com SLUS553D − MAY 2003 − REVISED JULY 2005 APPLICATION INFORMATION Programming the Thresholds The input-referenced thresholds for battery depleted, ac detection and charge voltage are defined by dimensioning the external dividers connected to pins BATDEP, ACDET and BATP. This calculation is simple, and consists of assuming that when the input voltage equals the desired threshold value the voltage at the related pin is equal to the pin internal reference voltage: Vinput = Vpin × (1 + Kres) where: Vinput = Target threshold, referenced to input signal Vpin = Internal reference(1.196 V for BATP; 1.246 V for BATDEP, ACDET) Kres = External resistive divider gain ( for instance: R24/R25 for BATP) When using external dividers with high absolute value the input bias currents for those pins must be included in the threshold calculation. On the bq24702/3 the input bias currents increase the actual value for the threshold voltage, when compared to the values calculated using the internal references and divider gain only: Vinput = Vpin × (1+Kres) + Vbias The increase on the threshold voltage is given by: Vbias = Rdiv × Ipin where: Vbias = Voltage increase due to pin bias current Rdiv = External resistor value for resistor connected from pin to input voltage Ipin = Maximum pin leakage current The effect of IB can be reduced if the resistor values are decreased. Dynamic Power Management The dynamic power management (DPM) feature allows a cost effective choice of an ac wall-adapter that accommodates 90% of the system’s operating-current requirements. It minimizes battery charge time by allocating available power to charge the battery (i.e. IBAT = IADPT − ISYS). If the system plus battery charge current exceeds the adapter current limit, as shown in Figure 1, the DPM feature reduces the battery charge current to maintain an overall input current consumption within user defined power capability of the wall-adapter. As the system’s current requirements decrease, additional current can be directed to the battery, thereby increasing battery charge current and minimizing battery charge time. The DPM feature is inherently designed into the PWM controller by inclusion of the three control loops, battery-charge regulation voltage, battery-charge current, and adapter-charge current, refer to Figure 2. If any of the three user programmed limits are reached, the corresponding control loop commands the PWM controller to reduce duty cycle, thereby reducing the battery charge current. www.ti.com 15 SLUS553D − MAY 2003 − REVISED JULY 2005 ADAPTER CURRENT LIMIT ADAPTER CURRENT SYSTEM CURRENT BATTERY CHARGE CURRENT NO CHARGE MAXIMUM CHARGE CURRENT DYNAMIC POWER MANAGEMENT MAXIMUM CHARGE CURRENT UDG−00113 Figure 1. Dynamic Power Management ACDET Operation The ACDET function senses the loss of adequate adapter power. If the voltage on ACDET drops below the internal VACPRES reference voltage, a loss of ADAPTER power is declared and the bq24702/bq24703 switches to battery power as the main system power. In addition, the bq24702/bq24703 shuts down its 5-V VREF and enters a low power sleep mode. Battery Charger Operation The bq24702/bq24703 fixed-frequency, PWM controller is designed to provide closed-loop control of battery charge-current (ICH) based on three parameters, battery-float voltage (VBAT), battery-charge current, and adapter charge current (IADPT). The bq24702/bq24703 is designed primarily for control of a buck converter using a high side P-channel MOSFET device (SW, refer to Figure 2). The three control parameters are voltage programmable through resistor dividers from the bq24702/bq24703 precision 5-V reference, an external or internal precision reference, or directly via a DAC interface from a keyboard controller. Adapter and battery-charge current information is sensed and fed back to two transconductance (gm ) amplifiers via low-value-sense resistors in series with the adapter and battery respectively. Battery voltage information is sensed through an external resistor divider and fed back from the battery to a third gm amplifier. Precharge Operation The precharge operation must be performed using the PWM regulator. The host can set the precharge current externally by monitoring the ALARM pin to detect a battery depleted condition and programming SRSET voltage to obtain the desired precharge current level. 16 www.ti.com SLUS553D − MAY 2003 − REVISED JULY 2005 Zero Volt Operating The zero volt operation is intended to provide a low current path to close open packs and protect the system in the event of a pack cell short-circuit condition or if a short is applied to the pack terminal. It is not designed to precharge depleted packs, as it is disabled at voltages that are not within normal pack operating range for precharge. If the voltage at BATDEP pin is below the zero volt operation threshold , charge is enabled (EN=HI), and ac is selected (ACSEL=HI) the bq24702/3 enters the zero volt operation mode. When the zero volt operation mode is on, the internal PWM is disabled, and an internal power MOSFET connects SRP to VCC. The battery charge current is limited by the filter resistor connected to SRP pin (R19). R19 must be dimensioned to withstand the worst case power dissipation when in zero volt operation mode. The zero volt operation mode is disabled when BATDEP is above the zero volt operation threshold, and the main PWM loop is turned on if charge is enabled, regulating the current to the value set by SRSET voltage. To avoid errors on the charge current both resistors on the SRP, SRN filter must have the same value. Note, however, that R21 (connected to SRN) does not dissipate any power when in zero volt operation and can be of minimum size. PWM Operation The three open collector gm amplifiers are tied to the COMP pin (refer to Figure 2), which is internally biased up by a 100-µA constant current source. The voltage on the COMP pin is the control voltage (VC) for the PWM comparator. The PWM comparator compares VC to the sawtooth ramp of the internally fixed 300-kHz oscillator to provide duty cycle information for the PWM drive. The PWM drive is level-shifted to provide adequate gate voltage levels for the external P-channel MOSFET. Refer to PWM selector switch gate drive section for gate drive voltage levels. Q1 SW ISW + VADPT D1 CLK OSC RAMP ENABLE S Q R Q LATCH OUT VCC LEVEL SHIFT 5V 100 µA VBAT PWM COMPARATOR PWM DRIVE 21 PWM VHSP FROM ENABLE LOGIC COMP 10 + 13 BATP ZCOMP ENABLE BATTERY VOLTAGE + 1.25 V BATTERY CHARGE CURRENT ADP CURRENT gm AMPLIFIERS UDG−00114 Figure 2. PWM Controller Block Diagram www.ti.com 17 SLUS553D − MAY 2003 − REVISED JULY 2005 Softstart Softstart is provided to ensure an orderly start-up when the PWM is enabled. When the PWM controller is disabled (ENABLE = Low), the 100-µA current source pullup is disabled and the COMP pin is actively pulled down to GND. Disabling the 100-µA pullup reduces current drain when the PWM is disabled. When the bq24702/bq24703 PWM is enabled (ENABLE = High), the COMP pin is released and the 100-µA pullup is enabled (refer to Figure 2). The voltage on the COMP pin increases as the pullup charges the external compensation network connected to the COMP pin. As the voltage on the COMP pin increases the PWM duty cycle increases linearly as shown in Figure 3. PERCENT DUTY CYCLE vs COMPENSATION VOLTAGE 100 90 Percent Duty Cycle − % 80 70 60 50 40 30 20 10 0 1.2 1.7 2.2 2.7 3.2 VCOMP − Compensation Voltage − V Figure 3 As any one of the three controlling loops approaches the programmed limit, the gm amplifier begins to shunt current away from the COMP pin. The rate of voltage rise on the COMP pin slows due to the decrease in total current out of the pin, decreasing the rate of duty cycle increase. When the loop has reached the programmed limit the gm amplifier shunts the entire bias current (100 µA) and the duty cycle remains fixed. If any of the control parameters tries to exceed the programmed limit, the gm amplifier shunts additional current from the COMP pin, further reducing the PWM duty cycle until the offending parameter is brought into check. Setting the Battery Charge Regulation Voltage The battery charge regulation voltage is programmed through the BATSET pin, if the internal precision reference is not used. The BATSET input is a high-impedance input that is driven by either a keyboard controller DAC or via a resistor divider from a precision reference (see Figure 4). The battery voltage is fed back to the gm amplifier through a resistor divider network. The battery charge regulation voltage can be defined as: V BATTERY + (R1 ) R2) V R2 BATSET V ) I BATP where IBATP = input bias current for pin BATP 18 www.ti.com R1 (1) SLUS553D − MAY 2003 − REVISED JULY 2005 The overall accuracy of the battery charge regulation voltage is a function of the bypassed 5-V reference voltage tolerance as well as the tolerances on R1 and R2. The precision voltage reference has a 0.5% tolerance making it suitable for the tight battery voltage requirements of Li-ion batteries. Tolerance resistors of 0.1% are recommended for R1 and R2 as well as any resistors used to set BATSET. The bq24702/bq24703 provides the capability of using an internal precision voltage reference through the use of a multiplexing scheme, refer to Figure 4, on the BATSET pin. When BATSET voltage is less than 0.25 V, an internal reference is switched in and the BATSET pin is switched out from the gm amplifier input. When the BATSET voltage is greater than 0.25 V, the BATSET pin voltage is switched in to the input of the gm amplifier and the voltage reference is switched out. NOTE:The minimum recommended BATSET is 1.0 V, if BATSET is used to set the voltage loop. VBAT BATP COMP 13 gm AMPLIFIER 10 + BATSET 9 0.25 V 1.25 V VBAT (a) VBATSET < 0.25 V R1 VREF = 5 V COMP BATP 13 gm AMPLIFIER 10 + R2 9 BATSET 0.25 V 1.196 V (b) VBATSET > 1 V UDG−00116 Figure 4. Battery Error Amplifier Input Multiplexing Scheme www.ti.com 19 SLUS553D − MAY 2003 − REVISED JULY 2005 Programming the Battery Charge Current The battery charge current is programmed via a voltage on the SRSET pin. This voltage can be derived from a resistor divider from the 5-V VREF or by means of an DAC. The voltage is converted to a current source that is used to develop a voltage drop across an internal offset resistor at one input of the SR gm amplifier. The charge current is then a function of this voltage drop and the sense resistor (RS), refer to Figure 5. RS COMP 10 SRP 2 kΩ 16 + VREF SRN 15 SRSET 5 + 25 kΩ UDG−00117 Figure 5. Battery Charge Current Input Threshold Function The battery charge current can be defined as: I V + SRSET BAT 25 R S (2) where VSRSET is the programming voltage on the SRSET pin. VSRSET maximum is 2.5 V. Programming the Adapter Current Like the battery charge current described previously, the adapter current is programmed via a voltage on the ACSET pin. That voltage can either be from an external resistor divider from the 5-V VREF or from an external DAC. The adapter current is defined as: I 20 ADPT + V ACSET 25 R S2 (3) www.ti.com SLUS553D − MAY 2003 − REVISED JULY 2005 COMPONENT SELECTION MOSFET Selection MOSFET selection depends on several factors, namely, gate-source voltage, input voltage, and input current. The MOSFET must be a P-channel device capable of handling at least 15-V gate-to-source with a drain-source breakdown of VBV~ VIN+1 V. The average input current can be approximated by: I (avg) + D IN Ichg A D = Duty cycle Ichg = Charge current (4) The RMS current through the MOSFET is defined as: I ǸD A (RMS) + Ichg IN RMS (5) The rise/fall times for pin PWM for the selected MOSFET should be greater than 40 nsec. Schottky Rectifier (Freewheeling) The freewheeling Schottky rectifier must also be selected to withstand the input voltage, VIN. The average current can be approximated from: I (avg) + Ichg D1 (1 * D) A (6) Choosing an Inductance Low inductance values result in a steep current ramp or slope. Steeper current slopes result in the converter operating in the discontinuous mode at a higher power level. Steeper current slopes also result in higher output ripple current, which may require a higher number or more expensive capacitors to filter the higher ripple current. In addition, the higher ripple current results in an error in the sensed battery current particularly at lower charging currents. It is recommended that the ripple current not exceed 20% to 30% of full scale dc current. L+ D ǒVIN * VBATǓ F Ichg Ripple S Ripple = % Ripple allowed (Ex.: 0,2 for 20% ripple) (7) Too large an inductor value results in the current waveform of Q1 and D1 in Figure 2 approximating a squarewave with an almost flat current slope on the step. In this case, the inductor is usually much larger than necessary, which may result in an efficiency loss (higher DCR) and an area penalty. Selecting an Output Capacitor For this application the output capacitor is used primarily to shunt the output ripple current away from the battery. The output capacitor should be sized to handle the full output ripple current as defined as: I c (RMS) + ǒVIN * VBATǓ F S L D A RMS (8) www.ti.com 21 SLUS553D − MAY 2003 − REVISED JULY 2005 Selecting an Input Capacitor The input capacitor is used to shunt the converter ripple current on the input lines. The capacitor(s) must have a ripple current (RMS) rating of: I RMS + Ǹ[Ichg (1–D)] 2 D ) [Ichg D] 2 (1–D) A RMS (9) In addition to shunting the converter input ripple when the PWM is operating, the input capacitor also acts as part of an LC filter, where the inductance component is defined by the ac adapter cable inductance and board trace inductance from adapter connector to filter capacitor. Overshoot conditions can be observed at VCC line during fast load transients when the adapter powers the load or when the adapter is hot-plugged . Increasing the input capacitor value decreases the overshoot at VCC. Avoid overshoot voltages at VCC in excess of the absolute maximum ratings for that pin. Compensating the Loop For the bq24702/bq24703 used as a buck converter, the best method of compensation is to use a Type II compensation network from the output of the transconductance amplifiers (COMP pin) to ground (GND) as shown in Figure 2. A Type II compensation adds a pole-zero pair and an additional pole at dc. The Type II compensation network places a zero at ǒ F +1 Z 2 p 1 R COMP C Z Ǔ Hz (10) and a pole at F +1 P 2 ǒ p 1 R COMP C Ǔ Hz P (11) For this battery charger application the following component values: CZ = 4.7 µF, CP = 150 pF, and RCOMP = 100 Ω, provides a closed loop response with more than sufficient phase margin, as long as the LC pole [1/2 × PI × sqrt (l×c)] is set below 10 kHz. The SRP/SRN filter (R19, R21, C8) and ACP/ACN filter (R13/R15/C3) are required to filter noise associated with the PWM switching. To avoid adding secondary poles to the PWM closed loop system those filters should be set with cutoff frequencies higher than 1 kHz. Selector Operation The bq24702/bq24703 allows the host controller to manually select the battery as the system’s main power source, without having to remove adapter power. This allows battery conditioning through smart battery learn cycles. In addition, the bq24702/bq24703 supports autonomous supply selection during fault conditions on either supply. The selector function uses low RDS(on) P-channel MOSFETs for reduced voltage drops and longer battery run times. NOTE: Selection of battery power whether manual or automatic results in the suspension of battery charging. 22 www.ti.com SLUS553D − MAY 2003 − REVISED JULY 2005 ADAPTER SELECT SWITCH ADAPTER INPUT SYSTEM LOAD (bq24702) PWM BATTERY CHARGER BAT ACDRV (bq24702) 24 BATTERY SELECTOR BATDRV CONTROL 23 BATTERY SELECT SWITCH UDG−00119 Figure 6. Selector Control Switches Autonomous Selection Operation Adapter voltage information is sensed at the ACDET pin via a resistor divider from the adapter input. The voltage on the ACDET pin is compared to an internally fixed threshold. An ACDET voltage less than the set threshold is considered as a loss of adapter power regardless of the actual voltage at the adapter input. Information concerning the status of adapter power is fed back to the host controller through ACPRES. The presence of adapter power is indicated by ACPRES being set high. A loss of adapter power is indicated by ACPRES going low regardless of which power source is powering the system. During a loss of adapter power, the bq24702/bq24703 obtains operating power from the battery through the body diode of the P-channel battery select MOSFET. Under a loss of adapter power, ACPRES (normally high) goes low, if adapter power is selected to power the system, the bq24702/bq24703 automatically switches over to battery power by commanding ACDRV high and BATDRV low. During the switch transition period, battery power is supplied to the load via the body diode of the battery select P-channel MOSFET. When adapter power is restored, the bq24702/bq24703 configures the selector switches according to the state of signals; ACSEL, and ACPRES. If the ACSEL pin is left high when ac power is restored, the bq24702/bq24703 automatically switches back to ac power. To remain on battery power after ac power is restored, the ACSEL pin must be brought low. Conversely, if the battery is removed while the system is running on battery power and adapter power is present, the bq24702/bq24703 automatically switches over to adapter power by commanding BATDRV high and ACDRV low. NOTE: For the bq24702 any fault condition that results in the selector MOSFET switches not matching their programmed states is indicated by the ALARM pin momentarily going high. Refer to Battery Depletion Detection Section for more information on the ALARM discrete. When switching between the ac adapter and battery the internal logic monitors the voltage at pins ACDRV and BATDRV to implement a break-before-make function, with typical dead time on the order of 150 nsec. The turnon times for the external ac/battery switches can be increased to minimize inrush peak currents; that can be accomplished by adding external resistors in series with the MOSFET gates(R18 and R26). Note, however, that adding those resistors effectively disables the internal break-before-make function for ac/battery-switches, as the MOSFET gate voltages can not be monitored directly. If external resistors are added to increase the rise/fall times for battery/ac switches the break-before-make has to be implemented with discrete external components, to avoid shoot-through currents between ac adapter and battery pack. This functionality can be implemented by adding diodes (D2/D9) that bypass the external resistors when turning off the external FETs. www.ti.com 23 SLUS553D − MAY 2003 − REVISED JULY 2005 Smart Learn Cycles When Adapter Power Is Present Smart learn cycles can be conducted when adapter power is present by asserting and maintaining the ACSEL pin low. The adapter power can be reselected at the end of the learn cycle by a setting ACSEL to a logic high, provided that adapter power is present. Battery charging is suspended while selected as the system power source. NOTE: On the bq24703 the ac adapter is switched to the load when the battery voltage reaches the battery depleted threshold; it can be used when the learn cycle does not require the battery voltage to go below the battery depleted threshold. If the learn cycle algorithm requires the battery voltage to go lower than the battery depleted voltage, the bq24702 should be used, as it does not switch the ac adapter to load upon battery depleted detection. System Break Before Make Function When selecting the battery as the system primary power source, the adapter power select MOSFET turns off, in a break-before-make fashion, before the battery select MOSFET turns on. To ensure that this happens under all load conditions, the system voltage (load voltage) can be monitored through a resistor divider on the VS pin. This function provides protection against switching over to battery power if the adapter selector switch were shorted and adapter power present. Setting the VS resistive divider gain with the same gain selected for the BATP resistive divider assures the battery switch is turned on only when the system voltage is equal or less than the battery voltage. This function can be eliminated by grounding the VS pin. The ACDET function senses the adapter voltage via a resistive divider (refer to application circuit).The divider can be connected either to the anode of the input blocking diode (directly to the adapter supply) or to the cathode of the input blocking diode (bq24702/3 VCC pin). When the divider is connected to the adapter supply, the adapter power removal is immediately identified and the sleep mode is entered, disabling the break-before-make function for system voltage (see section for system power switching) and coupling system voltage to the battery line. In normal operation with a battery present, the battery low impedance prevents any over-voltage conditions. However, if a pack is not present or the pack is open, the battery line voltage has a transient equal to the adapter voltage. The bq24703 SRP/SRN pins are designed to withstand this over-voltage condition, but avoid connection to the battery line of any external devices that are not rated to withstand the adapter voltage. Connecting the ACDET resistive divider input to the VCC node keeps the system break-before-make function enabled until the voltage at pin VS is lower than the voltage at pin BATP. However, note that when using this topology the VCC pin voltage can be held by capacitive loads at either the VCC or system (ac switch is on) nodes when the ac adapter is removed. As the ACDET divider is connected to the VCC line there is a time delay from ac adapter removal to ac adapter removal detection by the IC. This time is dependent on load conditions and capacitive load values at VCC and system lines. Battery Depletion Detection The bq24702/bq24703 provides the host controller with a battery depletion discrete, the ALARM pin, to alert the host when a depleted battery condition occurs. The battery depletion level is set by the voltage applied to the BATDEP pin through a voltage divider network. The ALARM output asserts high and remains high as long as the battery deplete condition exists, regardless of the power source selected. For the bq24702, the host controller must take appropriate action during a battery deplete condition to select the proper power source. The bq24702 remains on the selected power source. The bq24703, however, automatically reverts over to adapter power, provided the adapter is present, during a deep discharge state. The battery is considered as being in a deep discharge state when the battery voltage is less than (0.8 × depleted level). Feature sets for the bq24702 and bq24703 are detailed in Table 1. 24 www.ti.com SLUS553D − MAY 2003 − REVISED JULY 2005 SELECTOR/ALARM TIMING EXAMPLE The selector and ALARM timing example in Figure 7 illustrates the battery conditioning support. NOTE: For manual selection of wall power as the main power source, both the ACPRES and ACSEL signals must be a logic high. ACPRES ACSEL ACDRV BATDRV ALARM BATTERY DEPLETE CONDITION bq24703 ONLY UDG−00122 ACSEL (ACPRES) tBATSEL ACDRV tACSEL BATDRV BATDEP< 1 V t ACSEL BATDRV tBATSEL ACDRV UDG−00120 Figure 7. Battery Selector and ALARM Timing Diagram www.ti.com 25 SLUS553D − MAY 2003 − REVISED JULY 2005 PWM SELECTOR SWITCH GATE DRIVE Because the external P-channel MOSFETs (as well as the internal MOSFETs) have a maximum gate-source voltage limitation of the input voltage, VCC, cannot be used directly to drive the MOSFET gate under all input conditions. To provide safe MOSFET-gate-drive at input voltages of less than an intermediate gate drive voltage rail was established (VSHP). Where VHSP = VCC − 10 V. This ensures adequate enhancement voltage across all operating conditions. An external zener diode (D3) connected between VCC and VHSP is required for transient protection; its breakdown voltage should be above the maximum value for internal VHSP/VCC clamp voltage for all operating conditions. TRANSIENT CONDITIONS AT SYSTEM, OVER-VOLTAGE AT SYSTEM TERMINAL Overshoot conditions can be observed at the system terminal due to fast load transients and inductive characteristics of the system terminal to load connection. An overshoot at the system terminal can be directly coupled to the VCC and VBAT nodes, depending on the switch mode of operation. If the capacitors at VBAT and VCC can not reduce this overshoot to values below the absolute maximum ratings, it is recommended that an additional capacitor is added to the system terminal to avoid damage to IC or external components due to voltage overstress under those transient conditions. AC ADAPTER COLLAPSING DUE TO TRANSIENT CONDITIONS The ac adapter voltage collapses when the ac switch is on and a current load transient at the system exceeds the adapter current limit protection. Under those conditions the ac switch is turned off when the ac adapter voltage falls below the ac adapter detection threshold. If the system terminal to load impedance has an inductive characteristic, a negative voltage spike can be generated at the system terminal and coupled into the battery line via the battery switch backgate diode. In normal operation, with a battery present, this is not an issue, as the low battery impedance holds the voltage at battery line. However, if a battery is not present or the pack protector switches are open the negative spike at the system terminal is directly coupled to the SRP/SRN pins via the R19/R21 resistors. Avoid damage to the SRP/SRN pins if this transient condition happens in the application. If a negative voltage spike happens at system terminal and R19/R21 limit the current sourced from the pin to less than −50 mA (Ipin = Vsystem/R19), the pins SRP/SRN are not damaged and the external protection schottky diodes are not required. However, if the current under those transient conditions exceeds −50 mA, external schottky diodes must be added to clamp the voltage at pins SRP/SRN so they do not exceed the absolute maximum ratings specified (−0.3 V). IBAT AMPLIFIER A filter with a cutoff frequency smaller than 10 kHz should be added to the IBAT output to remove switching noise. POWER DISSIPATION CALCULATION During PWM operation, the power dissipated internally to the IC increases as the internal driver is switching the PWM FET on/off. The power dissipation figures are dependent on the external FET used, and can be calculated using the following equation: Pd(max) = [IDDOP + Qg × Fs(max)] × VADAP where: Qg= Total gate charge for selected PWM MOSFET IDDOP = Maximum quiescent current for IC VADAP = Maximum adapter voltage Fs(max) = Maximum PWM switching frequency The maximum junction temperature for the IC must be limited to 125°C, under worst case conditions. 26 www.ti.com SLUS553D − MAY 2003 − REVISED JULY 2005 TYPICAL CHARACTERISTICS ERROR AMPLIFIER REFERENCE vs JUNCTION TEMPERATURE BYPASSED 5-V REFERENCE vs JUNCTION TEMPERATURE 5.1 1.215 5.08 1.21 VREF − 5 -V Reference − V VFB − Error Amplifier Reference − V VCC = 18 V 1.205 1.2 1.195 1.19 1.185 VCC = 18 V 5.06 5.04 5.02 5 4.98 4.96 4.94 1.18 4.92 1.175 −40 10 60 TJ − Junction Temperature − _C 4.9 −40 110 125 10 60 110 125 TJ − Junction Temperature − _C Figure 8 Figure 9 OSCILLATOR FREQUENCY vs JUNCTION TEMPERATURE TOTAL SLEEP CURRENT vs JUNCTION TEMPERATURE 335 26 VCC = 18 V 325 24 f − Oscillator Frequency − kHz I SLEEP − Battery Sleep Current − µ A VCC = 18 V 22 20 18 16 315 305 295 285 275 265 255 245 14 −40 10 60 TJ − Junction Temperature − _C 110 125 Figure 10 235 −40 10 60 110 125 TJ − Junction Temperature − _C Figure 11 www.ti.com 27 SLUS553D − MAY 2003 − REVISED JULY 2005 BATTERY CURRENT SET ACCURACY vs BATTERY CURRENT SET VOLTAGE AC CURRENT SET ACCURACY vs AC CURRENT SET VOLTAGE 20 25 SRSET Full Scale = 2.5 V = Max Programmed Current TJ = 25°C AC Current Set Accuracy − % Battery Current Set Accuracy − % 25 15 10 5 0 1 1.25 1.5 1.75 2 2.25 2.5 0.25 0.5 0.75 VSRSET − Battery Current Set Voltage − V 20 ACSET Full Scale = 2.5 V = Max Programmed Current TJ = 25°C 15 10 5 0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5 VACSET − AC Current Set Voltage − V Figure 12 Figure 13 BOARD LAYOUT GUIDELINES Recommended Board Layout Follow these guidelines when implementing the board layout: 1. Do not place lines and components dedicated to battery/adapter voltage sensing (ACDET,BATDEP, VS), voltage feedback loop (BATP, BATSET if external reference is used) and shunt voltage sensing (SRP/SRN/ACP/ACN) close to lines that have signals with high dv/dt (PWM, BATDRV, ACDRV, VHSP) to avoid noise coupling. 2. Add filter capacitors for SRP/SRN (C8) and ACP/ACN (C3) close to IC pins 3. Add Reference filter capacitor C1 close to IC pins 4. Use an isolated, clean ground for IC ground pin and resistive dividers used in voltage sensing; use an isolated power ground for PWM filter cap and diode (C11/D4). Connect the grounds to the battery PACK− and adapter GND. 5. Place C7 close to VCC pin. 6. Place input capacitor C12 close to PWM switch (U3) source and R14. 7. Position ac switch (U2) to minimize trace length from ac switch source to input capacitor C12. 8. Minimize inductance of trace connecting PWM pin and PWM external switch U3 gate 9. Maximize power dissipation planes connected to PWM switch 10. Maximize power dissipation planes connected to SRP resistor if steady state in zero volt mode is possible 11. Maximize power dissipation planes connected to D1 28 www.ti.com PACKAGE OPTION ADDENDUM www.ti.com 27-Sep-2005 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Eco Plan (2) Qty BQ24702PW ACTIVE TSSOP PW 24 60 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM BQ24702PWG4 ACTIVE TSSOP PW 24 60 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM BQ24702PWR ACTIVE TSSOP PW 24 2000 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM BQ24702PWRG4 ACTIVE TSSOP PW 24 2000 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM BQ24703PW ACTIVE TSSOP PW 24 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM BQ24703PWR ACTIVE TSSOP PW 24 2000 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM BQ24703PWRG4 ACTIVE TSSOP PW 24 2000 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM BQ24703RHDR ACTIVE QFN RHD 28 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR BQ24703RHDRG4 ACTIVE QFN RHD 28 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR 60 Lead/Ball Finish MSL Peak Temp (3) (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS) or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis. Addendum-Page 1 MECHANICAL DATA MTSS001C – JANUARY 1995 – REVISED FEBRUARY 1999 PW (R-PDSO-G**) PLASTIC SMALL-OUTLINE PACKAGE 14 PINS SHOWN 0,30 0,19 0,65 14 0,10 M 8 0,15 NOM 4,50 4,30 6,60 6,20 Gage Plane 0,25 1 7 0°– 8° A 0,75 0,50 Seating Plane 0,15 0,05 1,20 MAX PINS ** 0,10 8 14 16 20 24 28 A MAX 3,10 5,10 5,10 6,60 7,90 9,80 A MIN 2,90 4,90 4,90 6,40 7,70 9,60 DIM 4040064/F 01/97 NOTES: A. B. C. D. All linear dimensions are in millimeters. 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