TI1 BQ24745RHDR Smbus-controlled multi-chemistry battery Datasheet

bq24745
SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011
www.ti.com
SMBus-Controlled Multi-Chemistry Battery Charger With Input
Current Detect Comparator and Charge Enable Pin
Check for Samples: bq24745
UGAT
PHAS
DCIN
27
26
25
24
23
22
ICREF
1
21
VDDP
ACIN
2
20
LGATE
VREF
3
19
PGND
EAO
4
18
CSOP
EAI
5
17
CSON
FBO
6
16
NC
CE
7
15
VFB
8
9
10
11
12
13
14
NC
bq24745
28 LD QFN
TOP VIEW
ACOK
•
•
28
GND
•
The bq24745 is a high-efficiency, synchronous
battery charger with an integrated input-current
comparator, offering low component count for
space-constrained, multi-chemistry battery-charging
applications. The input-current, charge-current, and
charge-voltage DACs allow very high regulation
accuracies that can be easily programmed by the
system power-management microcontroller using the
SMBus interface. The bq24745 charges two, three, or
four series Li+ cells, and is available in a 28-pin,
5-mm × 5 mm QFN package.
BOOT
•
DESCRIPTION
VDDSMB
•
•
•
Notebook and Ultra-Mobile Computers
Portable Data-Capture Terminals
Portable Printers
Medical Diagnostics Equipment
Battery Bay Chargers
Battery Backup Systems
ICOUT
•
•
•
•
•
•
•
SCL
•
APPLICATIONS
CSSN
•
•
SDA
•
NMOS-NMOS Synchronous Buck Converter
with 300-kHz Frequency and >95% Efficiency
30-ns Minimum Driver Dead-Time and 99.5%
Maximum Effective Duty Cycle
High-Accuracy Voltage and Current Regulation
– ±0.5% Charge Voltage Accuracy
– ±3% Charge Current Accuracy
– ±3% Adapter Current Accuracy
– ±2% Input Current Sense Amp Accuracy
Integration
– Input Current Comparator, With Adjustable
Threshold and Hysteresis
– Internal Soft-Start
Safety
– Dynamic Power Management (DPM)
Up to 19.2-V Battery Voltage
7-V–24-V AC/DC-Adapter Operating Range
Simplified SMBus Control Interface
– Charge Voltage DAC (1.024 V–19.2 V)
– Charge Current DAC (128 mA–8.064 A)
– 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
< 1-mA Input DCIN Current With Adapter
Present and Charge Disabled
28-Pin, 5-mm × 5-mm QFN Package
CSSP
•
•
VICM
FEATURES
1
1
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.
Copyright © 2007–2011, Texas Instruments Incorporated
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. These features reduce
battery-charge current when the input power limit is reached to avoid overloading the ac adaptor when supplying
the load and the battery charger simultaneously. A highly accurate current-sense amplifier enables precise
measurement of input current from the ac adapter, allowing monitoring the overall system power. If the adapter
current is above the programmed low-power threshold, a signal is sent to host so that the system optimizes its
performance to the power available from the adapter. An integrated comparator monitors the input current
through the current-sense amplifier, and indicates when the input current exceeds a programmable threshold
limit.
TYPICAL APPLICATIONS
VIN = 20 V, VBAT = 4-cell Li-Ion, ICHARGE = 4.5 A
Q1 (ACFET)
SI4835BDY
Q2 (RBFET)
SI4835BDY
ADAPTER +
CHRG_IN
RC1
2.2Ω
P
ADAPTER -
Controlled by
HOST
C6
1u
309k
1%
C2
0.1u
C3
0.1u
27
CSSN
28
CSSP
22
DCIN
2
R2
49.9k
1%
12
ACIN
GND
bq24745
+3.3V_ALWAYS
OR
+5V_ALWAYS
11
VDDSMB
UGATE
24
PHASE
23
BOOT
25
D1
R3
10k
DISCRETE
LOGIC
R10
10k
R11
10k
VDDP
C4
13
ACOK
3
VREF
1uF
ICOUT
Dig I/O
7
CE
9
SDA
10
SCL
8
VICM
14
NC
SMBus
100pF
21
LGATE
20
PGND
19
CSOP
18
VFB
C5
PACK+
C13
2x10u
5.6uH
PACK-
C10
0.1uF
C8
1u
CSON
R12
10k
DISCRETE
LOGIC
BAT54
RSR
0.010
L1
C7
0.1uF
Q4
FDS6680A
C9
0.1uF
26
HOST
(EC)
Q3
FDS6680A
N
RC6
10Ω
R1
C15
10uF
C14
10uF
N
C1
2.2u
RAC
0.010
P
16
NC
17
15
R22
100 Ω
ICREF
1
EAO
4
EAI
5
FBO
6
C23
51pF
C17
0.1uF
R19
7.5k
C21
2000pF
R21
200k
R20
20k
C22
130pF
(1) Pullup rail could be either VREF or other system rail.
Figure 1. Typical System Schematic Using External Input-Current Comparator (Discrete Logic) Instead of
Internal Comparator
2
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bq24745
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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
+3.3V_ALWAYS
OR
+5V_ALWAYS
PHASE 23
BOOT
11 VDDSMB
R3
10k
Q3
FDS6680A
UGATE 24
12 GND
N
2
R2
33.2k
1%
25
D1
C16
1u
BAT54
L1
C7
0.1uF
PACK+
VDDP 21
C8
R10
10k
R11
10k
C4
VREF
LGATE
20
PGND
19
CSOP
18
CSON
17
1uF
Q4
FDS6680A
C9
0.1uF
26 ICOUT
R12
10k
HOST
(EC)
PACK-
C10
0.1uF
1uF
N
3
R4
10k
C13
2x10uF
5.6uH
13 ACOK
DISCRETE
LOGIC
RSR
0.010
VFB 15
R22
100Ω
Dig I/O
7
CE
ICREF
9
SMBus
1
SDA
VREF
R7
200k
C17
0.1uF
R8
200k
10 SCL
8
DISCRETE
LOGIC
C5
100pF
VICM
EAO
4
EAI
5
FBO
6
C23
51pF
14 NC
16 NC
R19
7.5k
C21
2000pF
R20
20k
R21
200k
C22
130pF
R18
(1) Pullup rail could be either VREF or other system rail.
1400k
Figure 2. Typical System Schematic Using Internal Input-Current Comparator
ORDERING INFORMATION
PART NUMBER
PACKAGE
bq24745
28-pin 5-mm × 5-mm QFN
ORDERING NUMBER
(Tape and Reel)
QUANTITY
bq24745RHDR
3000
bq24745RHDT
250
PACKAGE THERMAL DATA
(1)
PACKAGE
θJA
TA = 40°C
POWER RATING
DERATING FACTOR
ABOVE TA = 25°C
QFN – RHD (1)
36°C/W
2.36 W
0.028 W/°C
For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI
Web site at www.ti.com.
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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. Connecting a positive feedback resistor from the
ICREF pin to the ICOUT pin programs the hysteresis.
2
ACIN
Adapter-detected voltage-set input. Program the adapter-detect threshold by connecting a resistor divider from the
adapter input to ACIN pin to GND. Adapter voltage is detected if the ACIN-pin voltage is greater than 2.4 V. The VICM
current-sense amplifier, ICOUT comparator, and ACOK output are active when the ACIN pin voltage is greater than
0.6 V.
3
VREF
3.3-V regulated voltage output. Place a 1-μF ceramic capacitor from VREF to the GND pin close to the IC. This
voltage could be used for ratiometric programming of voltage and current regulation and for programming the ICREF
threshold.
4
EAO
Error amplifier output for compensation. Connect the feedback-compensation components from EAO to EAI. Typically,
a capacitor in parallel with a series resistor and capacitor. This node is internally compared to the PWM sawtooth
oscillator signal.
5
EAI
Error amplifier input for compensation. Connect the feedback compensation components from EAI to EAO. Connect
the input compensation from FBO to EAI.
6
FBO
Feedback output for compensation. Connect the input compensation from FBO to EAI. Typically, a resistor in parallel
with a series resistor and capacitor.
7
CE
Charge enable active-high logic input. HI enables charge. LO disables charge.
8
VICM
Adapter current-sense-amplifier output. The VICM voltage is 20 times the differential voltage across CSSP-CSSN.
Place a 100-pF (max) or less ceramic decoupling capacitor from VICM to GND.
9
SDA
SMBus data input. Connect to the SMBus data line from the host controller. A 10-kΩ pullup resistor to the host
controller power rail is needed.
10
SCL
SMBus clock input. Connect to the SMBus clock line from the host controller. A 10-kΩ pullup resistor to the host
controller power rail is needed.
11
VDDSMB
Input voltage for SMBus logic. Connect a 3.3-V supply rail or 5-V rail to the VDDSMB pin. Connect a 0.1-μF ceramic
capacitor from VDDSMB to GND for decoupling.
12
GND
Analog ground. On PCB layout, connect to the analog ground plane, and only connect to PGND through the thermal
pad underneath the IC.
13
ACOK
Valid adapter active-high detect logic open-drain output. Pulled HI when Input voltage is above the ACIN programmed
threshold. Connect a 10-kΩ pullup resistor from the ACOK pin to pull up the supply rail.
14
NC
No connect. Pin floating internally.
15
VFB
Battery-voltage remote sense. Directly connect a Kelvin sense trace from the battery-pack positive terminal to the VFB
pin to sense the battery pack voltage accurately. Place a 0.1-μF capacitor from VFB to GND close to the IC to filter
high-frequency noise.
16
NC
No Connect. Pin floating internally.
17
CSON
Charge-current sense resistor, negative input. An optional 0.1-μF ceramic capacitor is placed from the CSON pin to
GND for common-mode filtering. A 0.1-μF ceramic capacitor is placed from CSON to CSOP to provide
differential-mode filtering.
18
CSOP
Charge-current sense resistor, positive input. A 0.1-μF ceramic capacitor is placed from CSOP pin to GND for
common-mode filtering. A 0.1-μF ceramic capacitor is placed from CSON to CSOP to provide differential-mode
filtering.
19
PGND
Power ground. On PCB layout, connect directly to the source of the low-side power MOSFET, and to the to ground
connection of the input and output capacitors of the charger. Only connect to GND through the thermal pad
underneath the IC.
20
LGATE
PWM low-side driver output. Connect to the gate of the low-side power MOSFET with a short trace.
21
VDDP
PWM low-side driver positive 6-V supply output. Connect a 1-μF ceramic capacitor from VDDP to the PGND pin, close
to the IC. Use for high-side driver bootstrap voltage by connecting a small signal Schottky diode from VDDP to BOOT.
22
DCIN
IC-power positive supply. Connect to the common-source (diode-OR) point: source of high-side P-channel MOSFET
and source of reverse blocking power P-channel MOSFET. Place a 1-μF ceramic capacitor from DCIN to the GND pin
close to the IC. Place a 10-Ω resistor from the adapter input to the DCIN pin to limit inrush current.
23
PHASE
PWM high-side driver negative supply. Connect to the phase-switching node (junction of the low-side power MOSFET
drain, high-side power MOSFET source, and output inductor). Connect the 0.1-μF bootstrap capacitor from PHASE to
BOOT.
24
UGATE
PWM high-side driver output. Connect to the gate of the high-side power MOSFET with a short trace.
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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. Place a positive-feedback resistor from the ICOUT pin to the ICREF pin for programming
hysteresis. The output is HI when the VICM pin voltage is lower than the ICREF pin voltage. The output is LO when
VICM pin voltage is higher than ICREF pin voltage.
27
CSSN
Adapter current-sense resistor, negative input. An optional 0.1-μF ceramic capacitor is placed from the CSSN pin to
GND for common-mode filtering. A 0.1-μF ceramic capacitor is placed from CSSN to CSSP to provide
differential-mode filtering.
28
CSSP
Adapter current-sense resistor, positive input. A 0.1-μF ceramic capacitor is placed from the CSSP pin to GND for
common-mode filtering. A 0.1-μF ceramic capacitor is placed from CSSN to CSSP to provide differential-mode
filtering.
ABSOLUTE MAXIMUM RATINGS
over operating free-air temperature range (unless otherwise noted) (1)
(2)
VALUE
–0.3 to 30
DCIN, CSOP, CSON, CSSP, CSSN, VFB, ACOK
Voltage range
UNIT
PHASE
–1 to 30
EAI, EAO, FBO, VDDP, LGATE, ACIN, VICM, ICOUT, ICREF, CE
–0.3 to 7
VDDSMB, SDA, SCL
–0.3 to 6
V
–0.3 to 3.6
VREF
–0.3 to 36
BOOT, UGATE with respect to GND and PGND
Maximum difference voltage: CSOP–CSON, CSSP–CSSN
–0.5 to 0.5
Junction temperature range
–40 to 155
°C
Storage temperature range
–55 to 155
°C
(1)
(2)
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 GND if not specified. Currents are positive into, and negative out of the specified terminal. Consult
Packaging Section of the data book for thermal limitations and considerations of packages.
RECOMMENDED OPERATING CONDITIONS
over operating free-air temperature range (unless otherwise noted)
MIN
Voltage range
NOM
MAX
–0.7
24
DCIN, CSOP, CSON, CSSP, CSSN, VFB, ACOK
0
24
VDDP, LGATE
0
6.5
PHASE
VREF
3.3
5.5
UNIT
V
EAI, EAO, FBO, ACIN, VICM, ICOUT, ICREF, CE
0
BOOT, UGATE with respect to GND and PGND
0
30
VDDSMB, SDA, SCL
0
5.5
Maximum difference voltage: CSOP–CSON, CSSP–CSSN
–0.3
0.3
Junction temperature range
–40
125
°C
Storage temperature range
–55
150
°C
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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%
12.529
ChargeVoltage() = 0x3130
VVFB_REG
_ACC
VFB charge-voltage regulation accuracy
8.350
4.154
TJ = 0 to 125°C, 1.024 V–19.2 V, Max DAC
value is 19.2 V
Charge-voltage regulation range
12.592
12.655
V
0.5%
8.4
–0.6%
ChargeVoltage() = 0x1060
RNG
0.5%
–0.5%
ChargeVoltage() = 0x20D0
VVFB_REG_
16.8
8.450
V
0.6%
4.192
4.230
V
–0.9%
0.9%
1.024
19.2
V
0
80.64
mV
CHARGE CURRENT REGULATION
VIREG_CHG_RNG
Charge-current regulation differential-voltage
range
VIREG_CHG = VCSOP – VCSON, max. DAC value
is 80.64 mV
3968
ChargeCurrent() = 0x0F80
–3%
2048
ChargeCurrent() = 0x0800
ICHRG_REG_ACC
mA
3%
–5%
Charge-current regulation accuracy
mA
5%
512
ChargeCurrent() = 0x0200
–25%
mA
25%
128
ChargeCurrent() = 0x0080
mA
–33%
33%
0
110.1
INPUT CURRENT REGULATION
VIREG_DPM_RNG
Adapter-current regulation differential-voltage
range
VIREG_DPM = VCSSP – VCSSN, max. DAC value
is 110.084 mV
InputCurrent() ≥ 0x0800
InputCurrent() = 0x0400
IINPUT_REG_ACC
Input-current regulation accuracy
InputCurrent() = 0x0100
InputCurrent() = 0x0080
4096
–3%
mV
mA
3%
2048
–5%
mA
5%
512
–25%
mA
25%
256
–33%
mA
33%
VREF REGULATOR
VVREF_REG
VREF regulator voltage
VACIN > 0.6 V, 0 – 30 mA
IVREF_LIM
VREF current limit
VVREF = 0 V, VACIN > 0.6 V
35
VACIN > 0.6 V, 0 – 50 mA
5.7
VVDDP = 0 V, VACIN > 0.6 V
90
VVDDP = 5 V, VACIN > 0.6 V
80
3.267
3.3
3.333
V
80
mA
6.3
V
VDDP REGULATOR
VVDDP_REG
IVDDP_LIM
6
VDDP regulator voltage
VDDP current limit
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6
135
mA
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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
2.25
IVICM
VICM output current
0
1
AVICM
Current-sense amplifier voltage gain
AVICM = VVICM/ VIREG_DPM
VIREG_DPM = V(CSSP–CSSN) ≥ 40 mV
Adapter-current sense accuracy
20
–2%
V/V
–3%
3%
VIREG_DPM = V(CSSP–CSSN) = 5 mV
–25%
25%
VIREG_DPM = V(CSSP–CSSN) = 1.5 mV
–33%
33%
Output-current limit
VVICM = 0 V
CVICM_MAX
Maximum output load capacitance
For stability with 0-mA to 1-mA load
V
mA
2%
VIREG_DPM = V(CSSP–CSSN) = 20 mV
IVICM_LIM
V
1
mA
100
pF
24
V
ACIN COMPARATOR INPUT UNDERVOLTAGE)
–20
VDCIN_VFB_OP
Differential voltage from DCIN to VFB
VACIN_CHG
ACIN rising threshold
Min. voltage to enable charging, VACIN rising
VACIN_CHG_HYS
ACIN falling hysteresis
VACIN falling
ACIN rising deglitch (1)
VACIN rising
ACIN falling deglitch
VACIN falling
VACIN_BIAS
Adapter present rising threshold
Min voltage to enable all bias, VACIN rising
VACIN_BIAS_HYS
Adapter present falling hysteresis
VACIN falling
20
VACIN rising
200
VACIN falling
1
ACIN rising deglitch
(1)
ACIN falling deglitch
2.376
2.4
2.424
40
50
100
150
0.62
μs
μs
1
0.56
V
mV
0.68
V
mV
μs
DCIN / VFB COMPARATOR (REVERSE DISCHARGING PROTECTION)
VDCIN-VFB_FALL
DCIN to VFB falling threshold
VDCIN-VFB__HYS
DCIN to VFB hysteresis
VDCIN – VVFB to turn off ACFET
140
185
240
mV
50
mV
DCIN to VFB rising deglitch
VDCIN – VVFB > VDCIN-VFB_RISE
1
ms
DCIN to VFB falling deglitch
VDCIN – VVFB < VDCIN-VFB_FALL
3.3
μs
VFB OVERVOLTAGE COMPARATOR
VOV_RISE
Overvoltage rising threshold
As percentage of VVFB_REG
104
VOV_FALL
Overvoltage falling threshold
As percentage of VVFB_REG
102
%
VFB SHORT (UNDERVOLTAGE and TRICKLE CHARGE) COMPARATOR
VVFB_SHORT_RISE VFB short rising threshold
VVFB_SHORT_HYS
2.6
VFB short falling hysteresis
VFB short rising deglitch
VVFB > VVFB_SHORT + VVFB_SHORT_HYS
Detection delay
VFB short falling deglitch
VVFB < VVFB_SHORT
ITRKL_REG_ACC
Trickle-charge current-regulation accuracy in
BATSHORT
VVFB < VVFB_SHORT
ILOW_MAX_REG
Maximum charge current regulation at low
voltage (<4 V)
VVFB_SHORT < VVFB < 4
2.7
2.9
mV
1.5
μs
μs
3.3
60
V
215
200
300
3
mA
A
CHARGE OVERCURRENT COMPARATOR
VOC
Charge overcurrent falling threshold
As percentage of IREG_CHG
145%
Minimum current limit (CSOP–CSON)
Internal filter pole frequency
50
mV
160
kHz
INPUT UNDERVOLTAGE LOCK-OUT COMPARATOR (UVLO)
UVLO
AC undervoltage rising threshold
VUVLO_HYS
AC undervoltage hysteresis, falling
Measure on DCIN pin
3.5
4
4.5
260
V
mV
INPUT CURRENT COMPARATOR
VICCOMP_OFFSET
(1)
Input current-comparator offset voltage
-6.8
0.12
6.8
mV
Verified by design.
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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
THERMAL SHUTDOWN COMPARATOR
TSHUT
Thermal shutdown rising temperature
TSHUT_HYS
Thermal shutdown hysteresis, falling
Temperature Increasing
155
°C
20
PWM HIGH SIDE DRIVER (UGATE)
RDS_HI_ON
High-side driver (HSD) turnon resistance
VBOOT – VPHASE = 5.5 V
6
Ω
RDS_HI_OFF
High-side driver turnoff resistance
VBOOT – VPHASE = 5.5 V
1
Ω
VBOOT_REFRESH
Bootstrap refresh comparator threshold
voltage
VBOOT – VPHASE when low-side refresh pulse
is requested
IBOOT_LEAK
BOOT leakage current when charge enabled
High side is on; charge enabled
4
V
200
μA
PWM LOW SIDE DRIVER (LGATE)
RDS_LO_ON
Low-side driver (LSD) turnon resistance
6
Ω
RDS_LO_OFF
Low-side driver turnoff resistance
1
Ω
PWM DRIVERS TIMING
Dead time when switching between LGATE
and UGATE , no load at LGATE and UGATE
Driver dead time
30
ns
PWM OSCILLATOR
FSW
PWM switching frequency
VRAMP_HEIGHT
PWM ramp height
240
As percentage of DCIN
360
6.67
kHz
%DCIN
QUIESCENT CURRENT
IOFF_STATE
Total off-state battery current from CSOP,
CSON, VFB, DCIN, BOOT, PHASE, etc
VVFB = 16.8 V, VACIN < 0.6 V,
VDCIN > 5 V, 0°C ≤ TJ ≤ 85°C
IBAT_ON
Battery on-state quiescent current
IBAT_LOAD_CD
7
10
μA
VVFB = 16.8 V, 0.6V < VACIN < 2.4 V,
VDCIN > 5 V
0.7
1
mA
Internal battery load current, charge disabled
Charge is disabled: VVFB = 16.8 V,
VACIN > 2.4 V, VDCIN > 5 V
0.7
1
mA
IBAT_LOAD_CE
Internal battery load current, charge enabled
Charge is enabled: VVFB = 16.8 V,
VACIN > 2.4 V, VDCIN > 5 V
10
12
mA
IAC
Adapter quiescent current
Charge disabled, VDCIN = 20 V
0.7
1
mA
Adapter switching quiescent current
Charge enabled, VDCIN = 20 V, converter
running
25
mA
IAC_SWITCH
6
INTERNAL SOFT START (8 Steps to Regulation Current ICHG)
Soft-start steps
Soft-start step time
8
step
1.5
ms
1.5
ms
CHARGER SECTION POWER-UP SEQUENCING
Charge-enable delay after power up
Delay from when adapter is detected to when
the charger is allowed to turn on
CHARGE UNDERCURRENT COMPARATOR (CYCLE-BY-CYCLE SYNCHRONOUS TO NON-SYNCHRONOUS)
VUCP
Cycle-by-cycle synchronous to
non-synchronous transition threshold
Cycle-by-cycle, (CSOP-CSON) voltage,
falling, LGATE turns off and latches off until
next cycle
Blankout time after LGATE turns on
Blankout comparator after LGATE turns on
5
10
15
100
mV
ns
LOGIC INPUT PIN CHARACTERISTICS (CE) (2) Pull-up CE with ≥2.2 kΩ resistor or directly to VREF.
VIN_LO
Input low-threshold voltage
VIN_HI
Input high-threshold voltage
VBIAS
Input bias current
0.8
V
1
μA
0.5
V
5.5
V
2.1
V = 0 TO VVDDP
OPEN-DRAIN LOGIC OUTPUT PIN CHARACTERISTICS (ACOK, ICOUT)
VOUT_LO
Output low saturation voltage
Sink current = 5 mA
VDDSMB INPUT SUPPLY FOR SMBus
VVDDSMB_RANGE
VDDSMB input voltage range
VVDDSMB_UVLO_
VDDSMB undervoltage lockout threshold
voltage, rising
VVDDSMB rising
2.4
2.5
2.6
V
VDDSMB undervoltage lockout hysteresis
voltage, falling
VVDDSMB falling
100
150
200
V
Threshold_Rising
VVDDSMB_UVLO_
Hyst_Rising
(2)
8
2.7
Pull up CE with ≥ 2-kΩ resistor, or connect directly to VREF.
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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 = 5.5 V, 0°C ≤ TJ ≤
85°C
TYP
MAX
20
27
UNIT
μA
ELECTRICAL CHARACTERISTICS
7 Vdc ≤ V(VCC) ≤ 24 Vdc, –20°C<TJ <125°C, ref = AGND (unless otherwise noted) (1)
PARAMETER
[SMB TIMING SPECIFICATION (VDD = 2.7 V to 5.5 V) (see Figures 4 and 5)]
MIN
TYP MAX
UNIT
SMBus TIMING CHARACTERISTICS
1
μs
tR
SCLK/SDATA rise time
tF
SCLK/SDATA fall time
tW(H)
SCLK pulse duration high
tW(L)
SCLK pulse duration low
4.7
μs
tSU(STA)
Setup time for START condition
4.7
μs
tH(STA)
START condition hold time after which first clock pulse is generated
4
μs
tSU(DAT)
Data setup time
250
ns
tH(DAT)
Data hold time
300
ns
tSU(STOP)
Setup time for STOP condition
4
μs
t(BUF)
Bus free time between START and STOP condition
4.7
FS(CL)
Clock frequency
10
4
300
ns
50
μs
μs
100
kHz
HOST COMMUNICATION FAILURE
ttimeout
SMBus bus release timeout
tWDI
Watchdog timeout period
22
25
35
ms
140
170
210
s
0.4
V
OUTPUT BUFFER CHARACTERISTICS
V(SDAL)
(1)
Output LO voltage at SDA, I(SDA) = 3 mA
Devices participating in a transfer time out when any clock low exceeds the 2- ms minimum time-out period. Devices that have detected
a time-out condition must reset the communication no later than the 35-ms maximum timeout period. Both a master and a slave must
adhere to the maximum value specified, as it incorporates the cumulative stretch limit for both a master (10 ms) and a slave (25 ms).
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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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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
-0.2
0
9
2000
4000 6000 8000 10000 12000 14000 16000 18000 20000
VFB programmed Setpoint - mV
Figure 6.
Figure 7.
CHARGE CURRENT REGULATION ACCURACY
vs
DAC ICHRG SETPOINT
CHARGE CURRENT REGULATION ACCURACY
vs
VFB (BATTERY) VOLTAGE
4.5
0
4
Battery Charge Current - A
Charge Current Accuracy - %
-2
-4
-6
-8
-10
-12
DCIN = 20 V,
VFB = 9 V
-14
1000
2000
3000
4000
5000
6000
7000
8000
3
2.5
2
1.5
1
3 CELL @ 12.592 V,
ICHG @ 4.096 A,
DCIN = 20 V
0.5
-16
0
3.5
9000
0
0
ICHG DAC Programmed Setpoint - mA
Figure 8.
2
4
6
8
Battery Voltage - V
10
12
14
Figure 9.
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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
-1.8
-2
0
-3
2000
4000
6000
8000
10000
12000
2000
DPM Programmed Setpoint - mA
INPUT CURRENT REGULATION (DPM)
AND CHARGE CURRENT
vs
SYSTEM CURRENT
INPUT CURRENT REGULATION (DPM) TRANSIENT
SYSTEM LOAD RESPONSE
CCM TO CCM
Ch1
2 A/div
5
4.5
4
3
3.5
2
Charge Current
Ch2
2 A/div
4
I(DCIN)
ILOAD
Ch3
2 A/div
Input Current
Input Current - A
Charge Current - A
5
I(SYS)
VICM
3
1
2.5
1
1.5
2
2.5
System Current - A
3
3.5
t − Time = 1 ms/div
4
Figure 12.
12
12000
Figure 11.
DCIN = 20 V
0.5
10000
Figure 10.
6
0
0
4000
6000
8000
DPM Program Value - mA
Ch4
500 mV/div
0
Figure 13.
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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 4.096A
with DCIN = 20 V
-3
4
5
6
7
9
8
10
11
12
13
Battery Voltage - V
Figure 14.
Figure 15.
EFFICIENCY
BATTERY CHARGE CURRENT
BATTERY REMOVAL (From Constant-Current Mode)
Ch4
2 V/div
98
4-Cell
96
VFB
94
Ch2
10 V/div
3-Cell
Efficiency - %
92
2-Cell
90
PH
1-Cell
88
Ch1
2 A/div
86
1 - 4 Cell
ICHG at 8.064A
with DCIN = 20 V
84
I(IND)
82
t − Time = 4 ms/div
80
0
1
2
3
4
5
6
7
8
9
Battery Charge Current - A
CHARGER WHEN ADAPTER INSERTED
ADAPTER REMOVED WHILE CHARGING
Ch1
5 V/div
Figure 17.
Ch1
5 V/div
Figure 16.
DCIN
VREF
ACOK
VREF
ACOK
Ch4
2 V/div
Ch3
2 V/div
ACIN
Ch4
2 V/div
Ch2
Ch3
2 V/div 2 V/div
DCIN
Ch2
10 V/div
PH
t − Time = 4 ms/div
t − Time = 4 ms/div
Figure 18.
Figure 19.
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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.
DEAD-TIME BETWEEN
UGATE OFF AND LGATE ON
DEAD-TIME BETWEEN
LGATE OFF AND UGATE ON
Ch1
2 A/div
I(IND)
PH
UGATE-PH
Ch4
10 V/div
Ch2
10 V/div
UGATE
Math1
5 V/div
Ch3
5 V/div
LGATE
Ch3
Ch2
5 V/div 10 V/div
Ch1
2 A/div
t − Time = 10 ms/div
I(IND)
UGATE
PH
UGATE-PH
LGATE
t − Time = 40 ns/div
t − Time = 40 ns/div
Figure 24.
14
Ch3
1 V/div
ACGOOD
Ch2
10 V/div
ACGOOD
Ch2
10 V/div
SDA
Ch3
1 V/div
SDA
Ch4
5 V/div
Ch1
2 V/div
t − Time = 10 ms/div
Ch4
10 V/div
Ch2
10 V/div
ACGOOD
Math1
5 V/div
Ch1
2 V/div
CHARGE ENABLE/DISABLE
Figure 25.
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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.
CONTINUOUS CONDUCTION MODE (CCM)
SWITCHING WAVEFORMS, ICHARGE = 3986 mA
DISCONTINUOUS CONDUCTION MODE (DCM)
SWITCHING WAVEFORMS, ICHARGE = 256 mA
PH
I(IND)
UGATE
PH
Ch3
5 V/div
t − Time = 1 ms/div
Figure 28.
Figure 29.
OFF-STATE BATTERY CURRENT (LOW Iq)
vs
VFB (BATTERY) VOLTAGE
OFF-STATE DCIN CURRENT (LOW Iq)
vs
DCIN INPUT VOLTAGE (With Adapter Connected)
700
6
600
Standby DCIN Current − mA
7
5
4
3
Including current from:
DCIN, CSSP/N, VFB,
CSOP/N, BOOT, PHASE
2
500
400
300
200
0
0
-100
5
10
15
VFB - Voltage - V
20
25
Adapter Connected
ACIN > 2.4 V,
Charge Disabled by CE pin
CE = Low
100
1
0
LGATE
Math1
5 V/div
UGATE-PH
LGATE
Math1
5 V/div
UGATE-PH
t − Time = 1 ms/div
I(DCIN) − Off-State Current − mA
Ch2
10 V/div
Ch3
Ch2
5 V/div 10 V/div
UGATE
Ch4
10 V/div
I(IND)
Ch1
500 mA/div
Figure 26.
Ch4
10 V/div
Ch1
2 A/div
t − Time = 400 ms/div
0
Figure 30.
5
10
15
DCIN - Voltage - V
20
25
Figure 31.
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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.
16
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FUNCTIONAL BLOCK DIAGRAM
0.6V
WAKEUP
-
ENA
ACOK
ACOK
+
2.4V
+
-
ACIN
3.3V
LDO
DCIN_UVLO
DCIN
VREF
VREF
ENA
DCIN_UVLO
CE
FBO
CSSP
+
20xV(CSSP-CSSN)
+
20X
IIN_REG
FBO
EAI
EAI
IIN_ER
COMP
ERROR
AMPLIFIER
CSSN
EAO
EAO
CHRG_ENA
-
BOOT
+
1V
VFB_DIV
VFB
+
VBAT_REG
BAT_ER
-
20uA
LEVEL
SHIFTER
UGATE
CSOP
+
20xV(CSOP-CSON)
20X
+
IBAT_ REG
CSON
DC-DC
CONVERTER
PWM LOGIC
ENA
ICH_ER
PHASE
20uA
DCIN
CHRG_ENA
-
V(BTST-PHASE)
VDDP
6V LDO
ACOK
CE
REFRESH
CBTST
+
LGATE
+
4V _
VDDSMB
IC Tj
+
155degC
-
TSHUT
PGND
`
SMBus
Logic
ENA
SDA
SCL
CHRG_V
(11 bit DAC)
CHRG_I
(6 bit DAC)
INPUT_I
(6 bit DAC)
104% X VBAT_REG
-
VFB_DIV
+
VBAT_REG
BAT_OVP
20xV(CSSP-CSSN)
ENA
VICM
1x
IBAT_REG
IIN_REG
145% X IBAT_REG
-
20xV(CSOP-CSON)
+
CHG_OCP
GND
V(CSOP-CSON)
-
CHG_UCP
+
10mV +VICM
ICREF
+
-
BAT_SHORT
DCIN
-
-
VFB
NC
+
DCIN_UVLO
+
- 2.5V
+
NC
4V +ICOUT
VDDSMB
-
VDDSMB_UVLO
+
2.5V +bq24745
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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. On the bq24745,
the ManufacturerID() command always returns 0x0040 and the DeviceID() command always returns 0x0006.
Table 2. Battery Charger SMBus Registers
REGISTER ADDRESS
REGISTER NAME
READ/WRITE
DESCRIPTION
POR STATE
POR
Voltage/Current
0x14
ChargeCurrent()
Read or write
6-bit charge-current setting
0x0000
0 mV
0x15
ChargeVoltage()
Read or write
11-bit charge-voltage
setting
0x0000
0 mA
0x3F
InputCurrent()
Read or write
6-bit input-current setting
0x0080
256 mA (10-mΩ RAC)
0xFE
ManufacturerID()
Read-only
Manufacturer ID
0x0040
–
0xFF
DeviceID()
Read-only
Device ID
0x0006
–
SMBus
The bq24745 receives control inputs from the SMBus interface. The bq24745 uses a simplified subset of the
commands documented in System Management Bus Specification V1.1, which can be downloaded from
www.smbus.org. The bq24745 uses the SMBus Read-Word and Write-Word protocols (Figure 33) to
communicate with the smart battery. The bq24745 performs only as an SMBus slave device with address
0b0001 001_ (0x12) and does not initiate communication on the bus. In addition, the bq24745 has two
identification (ID) registers (0xFE): a 16-bit device ID register and a 16-bit manufacturer ID register (0xFF).
The data (SDA) and clock (SCL) pins have Schmitt-trigger inputs that can accommodate slow edges. Choose
pullup resistors (10 kΩ, typ.) for SDA and SCL to achieve rise times according to the SMBus specifications.
Communication starts when the master signals a START condition, which is a high-to-low transition on SDA,
while SCL is high. When the master has finished communicating, the master issues a STOP condition, which is a
low-to-high transition on SDA, while SCL is high. The bus is then free for another transmission. Figure 34 and
Figure 35 show the timing diagram for signals on the SMBus interface. The address byte, command byte, and
data bytes are transmitted between the START and STOP conditions. The SDA state changes only while SCL is
low, except for the START and STOP conditions. Data is transmitted in 8-bit bytes and is sampled on the rising
edge of SCL. Nine clock cycles are required to transfer each byte in or out of the bq24745 because either the
master or the slave acknowledges the receipt of the correct byte during the ninth clock cycle.
18
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a) Write-Word Format
S
SLAVE
ADDRESS
W
ACK
COMMAND
BYTE
ACK
7 BITS
1b
1b
8 BITS
1b
8 BITS
MSB LSB
0
0
MSB LSB
0
MSB LSB
Preset to 0b0001001
LOW DATA
BYTE
ChargeCurrent() = 0x14
ChargeVoltage() = 0x15
InputCurrent() = 0x3F
D7
ACK
HIGH DATA
BYTE
ACK
1b
8 BITS
1b
0
MSB
D0
D15
LSB
P
0
D8
b) Read-Word Format
S
SLAVE
ADDRESS
W
ACK
COMMAND
BYTE
ACK
7 BITS
1b
1b
8 BITS
1b
MSB LSB
0
0
MSB LSB
0
Preset to 0b0001001
S
SLAVE
ADDRESS
R
ACK
LOW DATA
BYTE
ACK
HIGH DATA
BYTE
NACK
7 BITS
1b
1b
8 BITS
1b
8 BITS
1b
1
0
MSB
Register
ChargeMode() = 0x14
ChargeMode() = 0x15
ChargeMode() = 0x3F
LSB
Preset to
0b0001010
LEGEND:
S = START CONDITION OR REPEATED START CONDITION
ACK = ACKNOWLEDGE (LOGIC-LOW)
W = WRITE BIT (LOGIC-LOW)
MSB
D7
LSB
0
D0
MSB
D15
LSB
P
1
D8
P = STOP CONDITION
NACK = NOT ACKNOWLEDGE (LOGIC-HIGH)
R = READ BIT (LOGIC-HIGH)
MASTER TO SLAVE
SLAVE TO MASTER
Figure 33. SMBus Write-Word and Read-Word Protocols
Figure 34. SMBus Write Timing
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A
tLOW tHIGH
B
C
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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. SMBus Read Timing
BATTERY VOLTAGE REGULATION
The bq24745 uses a high-accuracy voltage regulator for charging voltage. The battery voltage regulation setting
is programmed by the host microcontroller (µC), through the SMBus interface that sets an 11-bit DAC. The
battery termination voltage is a function of the battery chemistry. Consult the battery manufacturer to determine
this voltage.
The VFB pin is used to sense the battery voltage for voltage regulation and should be connected as close to the
battery as possible, or directly on the output capacitor. A 0.1-µF ceramic capacitor from VFB to GND is
recommended to be as close to the VFB pin as possible to decouple high-frequency noise.
To set the output charge-voltage regulation limit, use the SMBus to write a 16-bit ChargeVoltage() command
using the data format listed in Table 3. The ChargeVoltage() command uses the Write-Word protocol (see
Figure 33). The command code for ChargeVoltage() is 0x15 (0b0001 0101). The bq24745 provides a 1.024-V to
19.200-V charge voltage range, with 16-mV resolution. Setting ChargeVoltage() below 1.024 V or above 19.2 V
clears the DAC and terminates charge.
On reset, the ChargeVoltage() and ChargeCurrent() values are cleared (0) and the charger remains off until both
the ChargeVoltage() and the ChargeCurrent() commands are sent. During reset, both high-side and low-side
FETs remain off until the charger is started.
Table 3. Charge Voltage Register (0x15)
BIT
(1)
20
BIT NAME
DESCRIPTION
0
–
Not used
1
–
Not used
2
–
Not used
3
–
Not used
4
Charge voltage, DACV 0
0 = Adds 0 mV of charger voltage
1 = Adds 16 mV of charger voltage (1)
5
Charge voltage, DACV 1
0 = Adds 0 mV of charger voltage
1 = Adds 32 mV of charger voltage (1)
6
Charge voltage, DACV 2
0 = Adds 0 mV of charger voltage
1 = Adds 64 mV of charger voltage (1)
7
Charge voltage, DACV 3
0 = Adds 0 mV of charger voltage
1 = Adds 128 mV of charger voltage (1)
8
Charge voltage, DACV 4
0 = Adds 0 mV of charger voltage
1 = Adds 256 mV of charger voltage (1)
9
Charge voltage, DACV 5
0 = Adds 0 mV of charger voltage
1 = Adds 512 mV of charger voltage (1)
10
Charge voltage, DACV 6
0 = Adds 0 mV of charger voltage
1 = Adds 1,024 mV of charger voltage
Must be used in conjunction with other bits for a minimum output of 1024 mV
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Table 3. Charge Voltage Register (0x15) (continued)
BIT
BIT NAME
DESCRIPTION
11
Charge voltage, DACV 7
0 = Adds 0 mV of charger voltage
1 = Adds 2,048 mV of charger voltage
12
Charge voltage, DACV 8
0 = Adds 0 mV of charger voltage
1 = Adds 4,096 mV of charger voltage
13
Charge voltage, DACV 9
0 = Adds 0 mV of charger voltage
1 = Adds 8,192 mV of charger voltage
14
Charge voltage, DACV 10
0 = Adds 0 mV of charger voltage
1 = Adds 16,384 mV of charger voltage
15
–
Not used
CHARGE CURRENT REGULATION
The ChargeCurrent() SMBus 6-bit DAC register sets the maximum charging current. Battery current is sensed by
resistor RSR connected between the CSOP and CSON pins. The maximum full-scale differential voltage between
CSOP and CSON is 80.64 mV. Thus, for a 0.010-Ω sense resistor, the maximum charging current is 8.064 A.
The CSOP and CSON pins are used to measure the voltage across RSR, which has a default value of 10 mΩ.
However, resistors of other values can also be used. A larger sense resistor results in a larger sense voltage and
higher regulation accuracy, but at the expense of higher conduction loss.
To set the charge current, use the SMBus to write a 16-bit ChargeCurrent() command using the data format
listed in Table 4. The ChargeCurrent() command uses the Write-Word protocol (see Figure 33). The command
code for ChargeCurrent() is 0x14 (0b0001 0100). When using a 10-mΩ sense resistor, the bq24745 provides a
charge current range of 128 mA to 8.064 A, with 128-mA resolution. Set ChargeCurrent() to 0 to terminate
charging. Setting ChargeCurrent() below 128 mA, or above 8.064 A, clears DAC and terminates charge.
The bq24745 includes a foldback current limit when the battery voltage is low. If the battery voltage is less than
3.6 V but above 2.5 V, any charge current limit above 3 A is clamped at 3 A. If the battery voltage is less than
2.5 V, the charge current is set to 220 mA until that voltage rises above 2.7 V. The ChargeCurrent() register is
preserved and becomes active again when the battery voltage is higher than 2.7 V. This function effectively
provides a fold-back current limit, which protects the charger during short circuit and overload.
On reset, the ChargeVoltage() and ChargeCurrent() values are cleared (0) and the charger remains off until both
the ChargeVoltage() and the ChargeCurrent() commands are sent. During reset, both high-side and low-side
FETs remain off until the charger is started.
Table 4. Charge Current Register (0x14), Using 10-mΩ Sense Resistor
BIT
BIT NAME
DESCRIPTION
0
–
Not used
1
–
Not used
2
–
Not used
3
–
Not used
4
–
Not used
5
–
Not used
6
–
Not used
7
Charge current, DACI 0
0 = Adds 0 mA of charger current
1 = Adds 128 mA of charger current
8
Charge current, DACI 1
0 = Adds 0 mA of charger current
1 = Adds 256 mA of charger current
9
Charge current, DACI 2
0 = Adds 0 mA of charger current
1 = Adds 512 mA of charger current
10
Charge current, DACI 3
0 = Adds 0 mA of charger current
1 = Adds 1,024 mA of charger current
11
Charge current, DACI 4
0 = Adds 0 mA of charger current
1 = Adds 2,048 mA of charger current
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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. System current normally fluctuates as portions of the system are powered up or down.
Without dynamic power management (DPM), the source must be able to supply the maximum system current
and the maximum charger input current simultaneously. By using DPM, the input current regulator reduces the
charging current to keep the input current from exceeding the limit set by the Input Current SMBus 6-bit DAC
register. With high-accuracy limiting, the current capability of the ac adaptor can be lowered, reducing system
cost.
The CSSP and CSSN pins are used to sense RAC with a default value of 10 mΩ. However, resistors of other
values can also be used. A larger a sense resistor results in a larger sense voltage and a higher regulation
accuracy, but at the expense of higher conduction loss.
The total input current, from a wall cube or other dc source, is the sum of the system supply current and the
current required by the charger. When the input current exceeds the set input current limit, the bq24745
decreases the charge current to provide priority to system load current. As the system supply rises, the available
charge current drops linearly to zero.
éI
´ VBATTERY ù
IINPUT = ISYSTEM + ê LO AD
ú + IBIAS
VIN ´ h
ë
û
(1)
where η is the efficiency of the dc-dc converter (typically 85% to 95%).
To set the input current limit, use the SMBus to write a 16-bit InputCurrent() command using the data format
listed in Table 5. The InputCurrent() command uses the Write-Word protocol (see Figure 33). The command
code for InputCurrent() is 0x3F (0b0011 1111). When using a 10-mΩ sense resistor, the bq24745 provides an
input-current limit range of 256 mA to 11.008 A, with 256-mA resolution. InputCurrent() settings from 1 mA to
256 mA clears DAC and terminates charge. On reset the input current limit is 256 mA.
Table 5. Input Current Register (0x3F), Using 10-mΩ Sense Resistor.
BIT
22
BIT NAME
DESCRIPTION
0
–
Not used
1
–
Not used
2
–
Not used
3
–
Not used
4
–
Not used
5
–
Not used
6
–
Not used
7
Charge current, DACS 0
0 = Adds 0 mA of charger current
1 = Adds 256 mA of charger current
8
Charge current, DACS 1
0 = Adds 0 mA of charger current
1 = Adds 512 mA of charger current
9
Charge current, DACS 2
0 = Adds 0 mA of charger current
1 = Adds 1,024 mA of charger current
10
Charge current, DACS 3
0 = Adds 0 mA of charger current
1 = Adds 2,048 mA of charger current
11
Charge current, DACS 4
0 = Adds 0 mA of charger current
1 = Adds 4,096 mA of charger current
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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. The adapter-detect
threshold should typically be programmed to a value greater than the maximum battery voltage and lower than
the minimum allowed adapter voltage. The ACIN divider should be placed before the input power path selector in
order to sense the true adapter input voltage.
If DCIN is below 4 V, the charger is disabled.
If ACIN is below 0.6 V but DCIN is above 4.5 V, AC and VICM are disabled and pulled down to GND. The total
quiescent current is less than 10 µA.
Once ACIN rises above 0.6 V and DCIN is above 4.5 V, VREF goes to 3.3 V and all the bias circuits are
enabled. ACOK low indicates ACIN still below 2.4 V, and the valid adaptor is not available. VICM becomes valid
to reflect the adapter current.
When ACIN keeps rising and passes 2.4 V, a valid ac adapter is present. 100 µs later, the following occurs:
• ACOK becomes high through an external pullup resistor to the host digital voltage rail.
• The charger turns on if all the conditions are satisfied. (see Enable and Disable Charging
)
ENABLE AND DISABLE CHARGING
The following conditions must be valid before charging is enabled:
• Not in UVLO (DCIN > 4.5 V, and VDDSMB >2.5 V)
• Adapter is detected (ACIN > 2.4 V).
• Adapter – Battery voltage is higher than the VDCIN-VFB comparator threshold.
• 200-μs delay is complete after adapter detection.
• SMBus ChargeVoltage(),ChargeCurrent() and InputCurrent() DAC registers are inside the valid range.
• CE is HIGH.
• 2-ms delay is complete after adapter is detected and CE goes HIGH.
• VDDP and VREF are valid.
• Not in thermal shutdown (TSHUT)
Any of the following conditions stops ongoing charging:
• SMBus ChargeVoltage(), ChargeCurrent(), or InputCurrent() DAC register is outside the valid range.
• CE is LOW.
• Adapter is removed (DCIN <4 V).
• VDDSMB supply is removed. (VDDSMB <2.35 V)
• Adapter – Battery voltage is less than VDCIN-VFB comparator threshold.
• Battery is over voltage.
• In thermal shutdown: TSHUT IC temperature threshold is above 155°C.
AUTOMATIC INTERNAL SOFT-START CHARGER CURRENT
The charger automatically soft-starts the output regulation current every time the charger is enabled to ensure
there is no overshoot or stress on the output capacitors or the power converter. The soft-start consists of
stepping up the charge regulation current in eight evenly divided steps up to the programmed charge current.
Each step lasts around 1.6 ms, for a typical rise time of 12.8 ms. No external components are needed for this
function. The regulation limits can be changed in the middle of charging without soft start.
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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).
The feedback compensation stage is connected between the error amplifier input (EAI) and error amplifier output
(EAO). The LC output filter selected gives a characteristic resonant frequency that is used to determine the
compensation to ensure there is sufficient phase margin for the target bandwidth.
fo +
The resonant frequency, fo, is given by:
1
2p ǸLoC o
An internal sawtooth ramp is compared to the internal EAO error control signal to vary the duty cycle of the
converter. The ramp height is one-fifteenth of the input adapter voltage, making it always directly proportional to
the input adapter voltage. This cancels out any loop gain variation due to a change in input voltage, and
simplifies the loop compensation. The ramp is offset by 200 mV in order to allow zero-percent duty cycle when
the EAO signal is below the ramp. The EAO signal is also allowed to exceed the sawtooth ramp signal in order to
get a 100% duty-cycle PWM request. Internal gate-drive logic allows achieving 99.98% duty cycle while ensuring
the N-channel upper device always has enough voltage to stay fully on. 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 to pull the PHASE node down and recharge the BOOT
capacitor. Then the high-side driver returns to 100% duty-cycle operation until the (BOOT-PHASE) voltage is
detected to fall low again due to leakage current discharging the BOOT capacitor below 4 V, and the recharge
pulse is reissued.
The fixed-frequency oscillator keeps tight control of the switching frequency under all conditions of input voltage,
battery voltage, charge current, and temperature, simplifying output filter design and keeping the frequency out of
the audible noise region. The type-III compensation provides phase boost near the cross-over frequency, giving
sufficient phase margin.
CONTINUOUS AND DISCONTINUOUS CONDUCTION MODES
In continuous-conduction mode (CCM), the inductor current always flows to charge the battery, and the charger
always operates in synchronized mode. At the beginning of each clock cycle, the high-side n-channel power
MOSFET turns on, and the turnon time is set by the voltage on EAO pin. After the high-side power MOSFET
turns off, the low-side n-channel power MOSFET turns on. During CCM, the low-side n-channel power MOSFET
stays on until the end of the clock cycle. The internal gate-drive logic ensures there is break-before-make
switching to prevent shoot-through currents. During the 25-ns dead time where both FETs are off, the back diode
of the low-side power MOSFET conducts the inductor current. Having the low-side FET turn on keeps the power
dissipation low, and allows safely charging at high currents. With type-III compensation, the loop has a fixed
2-pole system.
Before the ripple valley current gets close to zero, the low-side FET must turn off before current goes negative,
or flows from the battery to the PHASE node, to avoid battery boosting the system. After the high-side n-channel
power MOSFET turns off, and after the break-before-make dead-time, the low-side n-channel power MOSFET
turns on for a blank-out time. After the blank-out time is over, if the VCSOP-CSON voltage falls below the UCP
threshold (typical 10 mV), the low-side power MOSFET turns off and stays off until the beginning of the next
cycle, where the high-side power MOSFET is turned on again. After the low-side MOSFET turns off, the inductor
current flows through back-gate diode until it reaches zero. The negative inductor current is blocked by the diode,
and the inductor current becomes discontinuous. This mode is called discontinuous-conduction mode (DCM).
During the DCM mode, the loop response automatically changes and has a single-pole system at which the pole
is proportional to the load current, because the converter does not sink current, and only the load provides a
current sink. This means at very low currents the loop response is slower, as there is less sinking current
available to discharge the output voltage. At very low currents during non-synchronous operation, there may be a
small amount of negative inductor current during the 40-ns recharge pulse. The charge should be low enough to
be absorbed by the input capacitance.
Whenever the converter goes into zero percent duty-cycle, the high-side MOSFET does not turn on, and the
low-side MOSFET does not turn on (no 40-ns recharge pulse) either, and there is no discharge from the battery
unless the BOOT to PHASE voltage discharges below 4 V. In that case, it pulses once to recharge the bootstrap
capacitor.
24
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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. The 40-ns low-side MOSFET on-time is required protect
from ringing noise, and to ensure the bootstrap capacitor is always recharged and able to keep the high-side
power MOSFET on during the next cycle.
UCP (CHARGE UNDERCURRENT), USING SENSE RESISTOR
In the bq24745, the cycle-by-cycle UCP allows using very small inductors seamlessly, even if they have large
ripple current. Every cycle when the low-side MOSFET turns-on, if the CSOP-CSON voltage falls below 10 mV
(inductor current falls below 1 A if using a 10-mΩ sense resistor), the low-side MOSFET is latched off until the
next cycle begins and resets the latch.
The converter automatically detects when to turn off the low-side MOSFET every cycle. The converter goes into
discontinuous conduction mode (DCM) when the current falls below 1/2 the inductor peak-to-peak current ripple.
The inductor current ripple is given by
I
IDCM < RIPPLE
2
æ 1ö
æV
ö
(VIN -VBAT ) ´ ç BAT ÷ ´ ç ÷
è VIN ø
è fS ø
and IRIPPLE =
Lout
(2)
where
VIN: adapter voltage = DCIN voltage
VVFB: output voltage = VFB voltage
fS: switching frequency = 300 kHz
LOUT: output inductor
For proper cycle-by-cycle UCP sensing, the output filter capacitor should sit on CSON. Only a 0.1-µF capacitor is
on CSOP, close to the device input.
AVERAGE CHARGE OVERCURRENT, USING SENSE AMPLIFIER
The charger has average overcurrent protection using the VCSON-CSOP voltage across the charge-current sense
resistor. It monitors the charge current, and prevents the current from exceeding 145% of the programmed
regulated charge current. If the charge current limit falls below 3.3 A (on 10 mΩ), the overcurrent limit is fixed at
5 A. The high-side gate drive turns off when the overcurrent is detected, and automatically resumes when the
current falls below the overcurrent threshold. There is an internal 160-kHz filter pole, to filter the switching
frequency and prevent false tripping. This adds a small delay, depending on the amount of overdrive over the
threshold.
BATTERY OVERVOLTAGE PROTECTION, USING REMOTE SENSING VFB
The converter does not allow switching when the battery voltage at VFB exceeds 104% of the regulation voltage
set-point. Once the VFB voltage returns below 102% of the regulation voltage, switching resumes. This allows
quick response to an overvoltage condition, such as occurs when the load is removed or the battery is
disconnected. A current sink from CSOP and CSON to GND is on only during charging and allows discharging
the stored output inductor energy that is transferred to the output capacitors.
BATTERY TRICKLE CHARGING
The bq24745 automatically reduces the charge current limit to a fixed 220 mA to trickle-charge the battery when
the voltage on the VFB pin falls below 2.5 V. The charge current returns to the value programmed on the
ChargeCurrent(0x14) register when the VFB pin voltage rises above 2.7 V.
This function provides a safe trickle charge to close deeply discharged open packs.
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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 4.5 V and ACIN is above 0.6 V, VICM no longer stays at ground,
but becomes active. A user wanting to lower the voltage could use a resistor divider from VICM to GND and still
achieve accuracy over temperature.
A 100-pF capacitor connected on the output is recommended for decoupling high-frequency noise.
VDDSMB INPUT SUPPLY
The VDDSMB input provides bias power to the SMBus interface logic. Connect VDDSMB to an external 3.3-V or
5-V supply rail. SMBus communication can start between host and charger when the VDDSMB voltage is above
2.5 V and the VREF voltage is at 3.3 V. Bypass VDDSMB to GND with a 0.1-µF or greater ceramic capacitor.
INPUT UNDERVOLTAGE LOCKOUT (UVLO)
The system must have a minimum 4.5-V DCIN voltage to allow proper operation. When the DCIN voltage is
below 4 V, VREF LDO stays inactive, even with ACIN above 0.6 V. VREF turns on when DCIN > 4.5 V and ACIN
> 0.6 V. To enable VDDP requires DCIN > 4.5 V, ACIN > 2.4 V, and CE = HIGH.
VDDP GATE DRIVE REGULATOR
An integrated low-dropout (LDO) linear regulator provides a 6-V supply derived from DCIN for high efficiency,
and delivers over 90 mA of load current. The LDO powers the gate drivers of the n-channel switching MOSFETs.
Bypass VDDP to PGND with a 1-µF or greater ceramic capacitor. During thermal shutdown, the VDDP LDO is
disabled.
INPUT CURRENT COMPARATOR TRIP DETECTION
In order to optimize the system performance, the host monitors the adapter current. Once the adapter current is
above a threshold set via ICREF, the ICOUT pin sends a signal to the HOST. The signal alarms the host that
input power has exceeded the programmed limit, allowing the host to throttle back system power by reducing
clock frequency, lowering rail voltages, or disabling certain parts of the system. The ICOUT pin is an open-drain
output. Connect a pullup resistor to ICOUT. The output is logic HI when the VICM output voltage (VICM = 20 ×
VCSSP-CSSN) is lower than the ICREF input voltage. The ICREF threshold is set by an external resistor divider
using VREF. The hysteresis can be programmed by a positive feedback resistor from the ICOUT pin to the
ICREF pin.
26
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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. ACOK, ICREF, and ICOUT Logic
OPEN-DRAIN STATUS OUTPUTS (ACOK, ICOUT PINS)
Two status outputs are available; both require external pullup resistors to pull the pins to the system digital rail for
a high level.
The ACOK open-drain output goes high when ACIN is above 2.4 V. It indicates that a functional adapter is
providing a valid input voltage.
The ICOUT open-drain output goes low when the input current is higher than the threshold programmed via the
ICREF pin. Hysteresis can be programmed by adding a resistor from the ICREF pin to the ICOUT pin.
THERMAL SHUTDOWN PROTECTION
The QFN package has low thermal impedance, which provides good thermal conduction from the silicon to the
ambient, to keep the junction temperature low. As an added level of protection, the charger converter turns off
and self-protects whenever the junction temperature exceeds the TSHUT threshold of 155°C. VDDP LDO is
disabled as well during thermal shutdown. The charger stays off until the junction temperature falls below 135°C.
Once the temperature drops below 135°C, the VDDP LDO is enabled. If all the conditions described in the
Enable and Disable Charging section are valid, charge soft-starts again.
CHARGER TIME-OUT
The bq24745 includes a timer to terminate charging if the charger does not receive a ChargeVoltage() or
ChargeCurrent() command within 170 s. If a time-out occurs, both ChargeVoltage() and ChargeCurrent()
commands must be resent to re-enable charging.
CHARGE TERMINATION FOR Li-Ion OR Li-Polymer
The primary termination method for Li-Ion and Li-Polymer is minimum current. Secondary temperature
termination (see the Charge Current Regulation section) also provides additional safety. The host controls the
charge initiation and the termination. A battery pack gas gauge assists the hosts on setting the voltages and
determining when to terminate based on the battery-pack state of charge.
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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. Remote
sensing cancels the effect of impedance in series with the battery. This impedance normally causes the battery
charger to enter constant-voltage mode prematurely.
Component List for Typical System Circuit of Figure 2
Part Designator
Qty
Description
Q1, Q2,
3
P-channel MOSFET, –30-V, –7.5-A, SO-8, Vishay-Siliconix, Si4435
Q3, Q4
2
N-channel MOSFET, 30-V, 12.5-A, SO-8, Fairchild, FDS6680A
RAC, RSR
2
Sense resistor, 10-mW, 2010, Vishay-Dale, WSL2010R0100F
L1
1
Inductor, 5.6-uH, 7-A, 31-mΩ Vishay, IHLP2525CZ01-2R
D1
1
Diode, dual Schottky, 30-V, 200-mA, SOT23, Fairchild, BAT54C
C1
1
Capacitor, ceramic, 2.2-µF, 35-V, 10%, X7R
C6
1
Capacitor, ceramic, 1-µF, 35-V, 10%, X7R
2xC13, C14, C15
4
Capacitor, ceramic, 10-µF, 35-V, 20%, X5R, 1206, Panasonic, ECJ-3YB1E106M
C6, C16, C4, C8
4
Capacitor, ceramic, 1-µF, 25-V, 10%, X7R, 2012, TDK, C2012X7R1E105K
C2, C3, C7, C9, C10, C17
6
Capacitor, ceramic, 0.1-µF, 50-V, 10%, X7R, 0805, Kemet, C0805C104K5RACTU
C5
1
Capacitor, ceramic, 100- pF, 25-V, 10%, X7R, 0805, Kemet
C23
1
Capacitor, ceramic, 51-pF, 25-V, 10%, X7R, 0805, Kemet
C21
1
Capacitor, ceramic, 2000-pF, 25-V, 10%, X7R, 0805, Kemet
C22
1
Capacitor, ceramic, 130-pF, 25-V, 10%, X7R, 0805, Kemet
R3, R4, R10, R11, R12
5
Resistor, chip, 10-kΩ, 1/16-W, 5%, 0402
R1
1
Resistor, chip, 309-kΩ, 1/16-W, 1%, 0402
R2
1
Resistor, chip, 49.9-kΩ, 1/16-W, 1%, 0402
RC1
1
Resistor, thick film chip paralleling, 2× 3.9-Ω, 25-V, 1210
RC6
1
Resistor, thick film chip , 10-Ω, 1206
R19
1
Resistor, chip, 7.5-kΩ, 1/16-W, 5%, 0402
R20
1
Resistor, chip, 20-kΩ, 1/16-W, 1%, 0402
R21
1
Resistor, chip, 200-kΩ, 1/16-W, 5%, 0402
R22
1
Resistor, chip, 100-Ω, 1/16-W, 1%, 0402
R7, R8
2
Resistor, chip, 200-kΩ, 1/16-W, 1%, 0402
R18
1
Resistor, chip, 1.4-MΩ, 1/16-W, 1%, 0402
28
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Product Folder Link(s) :bq24745
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.
CSSP, CSSN Current Sense Supply positive and negative
These pins are used with an external low-value series resistor to monitor the current from
the adapter supply.
POR
Power-on reset
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Copyright © 2007–2011, Texas Instruments Incorporated
Product Folder Link(s) :bq24745
29
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 ................................................................................................................................................................ 1
•
Deleted Features Bullet: Cells Pin Supports Two to Four Li-Ion Cells ................................................................................. 1
•
Deleted Condition above Figure 1: VICMer_limit = 6 A ............................................................................................................ 2
•
Added text to the condition above Figure 2: "for ICOUT Input Current comparator" ........................................................... 3
•
Changed ICREF text in the PIN FUNCTIONS table From: Input current comparator voltage reference input. Connect
a resistor-divider from VREF to ICREF, and GND to program the reference for the LOPWR comparator To: Input
current comparator voltage reference input. Connect a resistor-divider from VREF to ICREF, and GND to program
the reference for the ICOUT comparator .............................................................................................................................. 4
Changes from Revision A (October 2008) to Revision B
Page
•
Deleted "Level 2" from title ................................................................................................................................................... 1
•
Deleted "Input Overvoltage Protection (OVP)" Features bullet ............................................................................................ 1
•
Changed Feature bullet from "6 V-24 V" to "7 V-24 V" ........................................................................................................ 1
•
Changed "10-μ" to "10-μA" Battery Current .......................................................................................................................... 1
•
Changed last sentence of first paragraph of DESCRIPTION by deleting "one," from the text string. .................................. 1
•
Changed Figure 1 graphic entity ........................................................................................................................................... 2
•
Changed Figure 2 graphic entity ........................................................................................................................................... 3
•
Changed TA from "70°C" to "40°C" in the Package Thermal Data table. ............................................................................. 3
•
Changed θJA from "39°C/W" to "36°C/W" in the Package Thermal Data table. .................................................................... 3
•
Changed "ACOUT" to "ICOUT" and deleted "ICREF input" from Pin 2 functional description. ........................................... 4
•
Deleted "optional" from Pins 17, 18, 27, and 28 functional description in the Pin Functions table. ..................................... 4
•
Added text to Pin 22 functional description. ......................................................................................................................... 4
•
Changed Pin 22 functional description from "100-Ω" resistor to "10-Ω" resistor in the Pin Functions table. ....................... 4
•
Added "ACOK" specification to first row of Absolute Maximum Ratings table. .................................................................... 5
•
Added "SDA" and "SCL" specification to fourth row of Absolute Maximum Ratings table, and changed maximum
voltage from "7 V" to "6 V" .................................................................................................................................................... 5
•
Deleted "GND" and "PGND" specification from Absolute Maximum Ratings table .............................................................. 5
•
Added "ACOK" specification to Recommended Operating Conditions table ........................................................................ 5
•
Added "VDDSMB", "SDA", and "SCL" specifications to Recommended Operating Conditions table .................................. 5
•
Changed VFB SHORT (....) COMPARATOR specification parameter text from ""VFB short rising hysteresis" to "VFB
short falling hysteresis" ......................................................................................................................................................... 7
•
Changed Functional Block Diagram graphic entity ............................................................................................................. 17
•
Changed Detailed Description -- re-write for clarification ................................................................................................... 18
•
Changed Figure 33 graphic entity ....................................................................................................................................... 19
•
Changed Figure 34 graphic entity legend ........................................................................................................................... 19
•
Changed Figure 35 graphic entity legend ........................................................................................................................... 20
•
Changed Figure 36 graphic entity ....................................................................................................................................... 27
•
Deleted "Q5" from Component List table. ........................................................................................................................... 28
•
Added description for C1 and C6 in the Component List table. ......................................................................................... 28
•
Changed "R9" to "R19" in Component List ......................................................................................................................... 28
•
Added R20 to Component List ............................................................................................................................................ 28
30
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Copyright © 2007–2011, Texas Instruments Incorporated
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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 ............................................................................................................................................ 28
Changes from Revision B (April 2010) to Revision C
•
Page
Changed Table 5 , Bit 7 description from "128mA" to "256mA"; Bit 8 description from "256mA" to "512mA"; Bit 9
description from "512mA" to "1024mA"; Bit 10 description from "1024mA" to "2048mA"; Bit 11 description from
"2048mA" to "4096mA"; and Bit 12 description from "4096mA" to "8192 mA". .................................................................. 22
Changes from Revision C (April 2011) to Revision D
Page
•
Corrected pin numbers on pins CSSN, CSSP, CSON, and CSOP in Figure 1 .................................................................... 2
•
Corrected pin numbers on pins CSSN, CSSP, CSON, and CSOP in Figure 2 .................................................................... 3
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Copyright © 2007–2011, Texas Instruments Incorporated
Product Folder Link(s) :bq24745
31
PACKAGE OPTION ADDENDUM
www.ti.com
11-Apr-2013
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
Lead/Ball Finish
(2)
MSL Peak Temp
Op Temp (°C)
Top-Side Markings
(3)
(4)
BQ24745RHDR
ACTIVE
VQFN
RHD
28
3000
Green (RoHS
& no Sb/Br)
CU NIPDAU
Level-2-260C-1 YEAR
0 to 125
BQ
24745
BQ24745RHDRG4
ACTIVE
VQFN
RHD
28
3000
Green (RoHS
& no Sb/Br)
CU NIPDAU
Level-2-260C-1 YEAR
0 to 125
BQ
24745
BQ24745RHDT
ACTIVE
VQFN
RHD
28
250
Green (RoHS
& no Sb/Br)
CU NIPDAU
Level-2-260C-1 YEAR
0 to 125
BQ
24745
BQ24745RHDTG4
ACTIVE
VQFN
RHD
28
250
Green (RoHS
& no Sb/Br)
CU NIPDAU
Level-2-260C-1 YEAR
0 to 125
BQ
24745
(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), Pb-Free (RoHS Exempt), 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.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between
the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.
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.
(4)
Multiple Top-Side Markings will be inside parentheses. Only one Top-Side Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a
continuation of the previous line and the two combined represent the entire Top-Side Marking for that device.
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
Samples
PACKAGE OPTION ADDENDUM
www.ti.com
11-Apr-2013
Addendum-Page 2
PACKAGE MATERIALS INFORMATION
www.ti.com
18-Aug-2014
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
1.1
8.0
12.0
Q2
BQ24745RHDT
VQFN
RHD
28
250
180.0
12.4
5.3
5.3
1.1
8.0
12.0
Q2
Pack Materials-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
18-Aug-2014
*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
35.0
Pack Materials-Page 2
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