Product
Folder
Order
Now
Support &
Community
Tools &
Software
Technical
Documents
BQ24072T, BQ24075T, BQ24079T
SLUS937C – DECEMBER 2009 – REVISED DECEMBER 2019
BQ2407xT Standalone 1-Cell 1.5-A Linear Battery Charger with Power Path and
Voltage-Based TS
1 Features
3 Description
•
•
The BQ2407xT series of devices are integrated Li-ion
linear chargers and system power path management
devices
targeted
at
space-limited
portable
applications. The devices operate from either a USB
port or AC adapter and support charge currents up to
1.5A. The input voltage range with input over-voltage
protection supports unregulated adapters. The USB
input current limit accuracy and start up sequence
allow the BQ2407xT to meet USB-IF inrush current
specification. Additionally, the input dynamic power
management (VIN - DPM) prevents the charger from
crashing incorrectly configure USB sources.
1
•
•
•
•
•
•
•
•
•
•
•
•
•
Fully Compliant USB Charger
Selectable 100 mA and 500 mA maximum input
current
100 mA Maximum current limit ensures
compliance to USB-IF standard
Input based dynamic power management (VIN-DPM)
for protection against poor USB sources
28 V Input lting with over-voltage protection
Integrated dynamic power path management
(DPPM) function simultaneously and
independently powers the system and charges the
battery
System output tracks battery voltage (BQ24072T)
Supports up to 1.5 A charge current with current
monitoring output (ISET)
Programmable Input Current Limit up to 1.5 A for
wall adapters
Battery disconnect function with SYSOFF input
Reverse current, short-circuit and thermal
protection
Flexible voltage based NTC thermistor input
Proprietary start up sequence limits inrush current
Status indication – charging/done, power good
Small 3 mm × 3 mm 16 Lead VQFN Package
The BQ2407xT features dynamic power path
management (DPPM) that powers the system while
simultaneously and independently charging the
battery. The DPPM circuit reduces the charge current
when the input current limit causes the system output
to fall to the DPPM threshold; thus, supplying the
system load at all times while monitoring the charge
current separately. This feature reduces the number
of charge and discharge cycles on the battery, allows
for proper charge termination and enables the system
to run with a defective or absent battery pack.
Device Information(1)
PART NUMBER
PACKAGE
BODY SIZE (NOM)
BQ24072T
BQ24075T
VQFN (16)
3.00 mm x 3.00 mm
BQ24079T
Smart phones
PDAs
MP3 players
Low-power handheld devices
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Simplified Circuit
1 k:
1 k:
Adaptor
IN
DC
GND
7
9
CHG
•
•
•
•
PGOOD
2 Applications
SYSTEM
OUT 10
13
11
1PF
4.7 PF
System
ON /OFF
Control
EN2 5
BQ24075T
BQ24079T
BQ24072T
8 VSS
BAT 2
3
15 SYSOFF
4.7 PF
TS 1
CE EN1 ILIM
4
6
12
ISET
TEMP
PACK+
TRM
16
14
PACK-
1.18 k:
1.13 k:
13 k:
10 k:
V IN
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
BQ24072T, BQ24075T, BQ24079T
SLUS937C – DECEMBER 2009 – REVISED DECEMBER 2019
www.ti.com
Table of Contents
1
2
3
4
5
6
7
8
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Description (continued).........................................
Device Options.......................................................
Pin Configuration and Functions .........................
Specifications.........................................................
8.1
8.2
8.3
8.4
8.5
8.6
9
1
1
1
2
3
3
4
6
Absolute Maximum Ratings ..................................... 6
ESD Ratings.............................................................. 6
Recommended Operating Conditions....................... 6
Thermal Information .................................................. 7
Electrical Characteristics........................................... 7
Typical Characteristics ............................................ 10
Detailed Description ............................................ 13
9.1
9.2
9.3
9.4
Overview .................................................................
Functional Block Diagram .......................................
Feature Description.................................................
Device Functional Modes........................................
13
13
14
20
10 Applications and Implementation...................... 25
10.1 Application Information.......................................... 25
10.2 Typical Applications .............................................. 25
11 Power Supply Recommendations ..................... 31
11.1 Power On .............................................................. 31
12 Layout................................................................... 33
12.1 Layout Guidelines ................................................. 33
12.2 Layout Example .................................................... 33
12.3 Thermal Package .................................................. 34
13 Device and Documentation Support ................. 35
13.1
13.2
13.3
13.4
13.5
13.6
13.7
Device Support ....................................................
Related Links ........................................................
Receiving Notification of Documentation Updates
Support Resources ...............................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
35
35
35
35
35
35
35
14 Mechanical, Packaging, and Orderable
Information ........................................................... 35
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision B (November 2014) to Revision C
Page
•
Changed the data sheet title ................................................................................................................................................. 1
•
Moved Storage temperature From: the ESD table to the Absolute Maximum Ratings.......................................................... 6
•
Changed the Handling Ratings table to ESD Ratings............................................................................................................ 6
•
Changed VIN-LOW To: IN-DPM in the Electrical Characteristics Power Path section ................................................................... 7
•
Changed VIN-LOW To VIN-DPM in the Functional Block Diagram ............................................................................................. 13
•
Changed: "R3 must be added.." To: "R8 must be added..." in the Battery Pack Temperature Monitoring section ............. 20
•
Changed R6 From: 10 kΩ To: 19.1 kΩ and R7 From: 13.2 kΩ To: 8.25 kΩ in Figure 23 .................................................. 25
•
Changed text: "which for this case are R6 = 8.25 kΩ and R7 = 19.1kΩ.." To: "which for this case are R7 = 8.25 kΩ
and R6 = 19.1 kΩ" ................................................................................................................................................................ 26
•
Changed Equation 8 ............................................................................................................................................................ 34
Changes from Revision A (April 2010) to Revision B
Page
•
Added Handling Rating table, Feature Description section, Device Functional Modes, Application and
Implementation section, Power Supply Recommendations section, Layout section, Device and Documentation
Support section, and Mechanical, Packaging, and Orderable Information section................................................................ 1
•
Deleted text from the Pin Configuration and Functions section: "Pin out designations are not final. Subject to
change." ................................................................................................................................................................................. 4
•
Changed VO(REG) to VBAT(REG) in Min Typ Max columns on the VRCH spec. of Electrical Characteristics table under
sub section BATTERY CHARGER......................................................................................................................................... 8
•
Changed IOUT 5.5 V To VOUT 5.5 V in Figure 28 .................................................................................................................. 27
2
Submit Documentation Feedback
Copyright © 2009–2019, Texas Instruments Incorporated
Product Folder Links: BQ24072T BQ24075T BQ24079T
BQ24072T, BQ24075T, BQ24079T
www.ti.com
SLUS937C – DECEMBER 2009 – REVISED DECEMBER 2019
Changes from Original (December 2009) to Revision A
Page
•
Added BQ24072T device to data sheet header ..................................................................................................................... 1
•
Added BQ24072T feature bullet ............................................................................................................................................. 1
•
Added "BQ24072T" to graphic entity...................................................................................................................................... 1
•
Added BQ24072T spec. to Ordering Info table ...................................................................................................................... 3
•
Added BQ24072T Pin Diagram .............................................................................................................................................. 4
•
Added BQ24072T to VO(REG) in the Electrical Characteristics Power Path section ................................................................ 7
•
Added "BQ24072T" to VDPPM in the Electrical Characteristics table....................................................................................... 8
•
Added "BQ24072T" to VBAT(REG) the Electrical Characteristics table...................................................................................... 8
•
Added BQ24072T Termination Disable (TD) description ..................................................................................................... 17
•
Added graphic entity for BQ24072T DPPM and Battery Supplement Modes ...................................................................... 23
•
Added graphic entity for BQ24072T Host Controlled Charger application........................................................................... 29
•
Added Termination Disable operation procedure. ................................................................................................................ 29
5 Description (continued)
Additionally, the regulated system input enables instant system turn-on when plugged in even with a totally
discharged battery. The power-path management architecture also permits the battery to supplement the system
current requirements when the adapter cannot deliver the peak system currents, enabling the use of a smaller
adapter.
The battery is charged in three phases: conditioning, constant current, and constant voltage. In all charge
phases, an internal control loop monitors the IC junction temperature and reduces the charge current if the
internal temperature threshold is exceeded. The charger power stage and charge current sense functions are
fully integrated. The charger function has high accuracy current and voltage regulation loops, charge status
display, and charge termination. The input current limit and charge current are programmable using external
resistors.
6 Device Options
PART NO.
VOVP
VBAT(REG)
VOUT(REG)
VDPPM
OPTIONAL
FUNCTION
BQ24072TRGTR
6.6 V
4.2 V
VBAT + 225 mV
VOREG –100 mV
TD
BQ24072TRGTT
6.6 V
4.2 V
VBAT + 225 mV
VOREG –100 mV
TD
BQ24075TRGTR
6.6 V
4.2 V
5.5 V
4.3 V
SYSOFF
BQ24075TRGTT
6.6 V
4.2 V
5.5 V
4.3 V
SYSOFF
BQ24079TRGTR
6.6 V
4.1 V
5.5 V
4.3 V
SYSOFF
BQ24079TRGTT
6.6 V
4.1 V
5.5 V
4.3 V
SYSOFF
Copyright © 2009–2019, Texas Instruments Incorporated
Product Folder Links: BQ24072T BQ24075T BQ24079T
Submit Documentation Feedback
3
BQ24072T, BQ24075T, BQ24079T
SLUS937C – DECEMBER 2009 – REVISED DECEMBER 2019
www.ti.com
7 Pin Configuration and Functions
9
CHG
BAT
2
ISET
TD
TMR
IN
15
14
13
IN
OUT
1
13
10
TS
TMR
OUT
14
11
SYSOFF
2
ILIM
15
BAT
12
ISET
1
BQ24075T and BQ24079 RGT Package
QFN 16 Pin
Top View
16
TS
16
BQ24072T RGT Package
QFN 16 Pin
Top View
12
ILIM
11
OUT
10
OUT
9
CHG
Th ermal
8
VSS
No t to scale
7
4
PGOOD
CE
Pad
6
3
EN1
8
VSS
BAT
5
7
PGOOD
Th ermal
EN2
6
4
EN1
CE
Pad
5
3
EN2
BAT
No t to scale
Pin Functions
PIN
NUMBER
NAME
DESCRIPTION
BQ24072T
BQ24075T
BQ24079T
I/O
1
1
I/O
External NTC Thermistor Input. Connect the TS input to the center tap of a resistor divider from VIN to
GND with the NTC in parallel with the bottom resistor to monitor the NTC in the battery pack. For
applications that do not utilize the TS function, set the resistor divider to be a 20% ratio. See the Battery
Pack Temperature Monitoring section for details on calculating the resistor values.
BAT
2, 3
2, 3
I/O
Charger Power Stage Output and Battery Voltage Sense Input. Connect BAT to the positive terminal of
the battery. Bypass BAT to VSS with a 4.7μF to 47μF ceramic capacitor.
CE
4
4
I
Charge Enable Active-Low Input. Connect CE to a high logic level to place the battery charger in standby
mode. In standby mode, OUT is active and battery supplement mode is available. Connect /CE to a low
logic level to enable the battery charger. CE is internally pulled down with ~285kΩ. Do not leave CE
unconnected to ensure proper operation.
EN2
5
5
I
EN1
6
6
I
Input Current Limit Configuration Inputs. Use EN1 and En2 to control the maximum input current and
enable USB compliance. See for the description of the operation states. EN1 and EN2 are internally
pulled down with ~285kΩ. Do not leave EN1 or EN2 unconnected to ensure proper operation.
PGOOD
7
7
O
Open-Drain Power Good Status Indication Output. PGOOD pulls to VSS when a valid input source is
detected. PGOOD is high-impedance when the input power is not within specified limits. Connect
PGOOD to the desired logic voltage rail using a 1kΩ to 100kΩ resistor, or use with an LED for visual
indication.
VSS
8
8
–
Ground. Connect to the thermal pad and to the ground rail of the circuit.
CHG
9
9
O
Open-Drain Charging Status Indication Output. CHG pulls to VSS when the battery is charging. CHG is
high-impedance when charging is complete or when the charger is disabled. CHG flashes to indicate a
timer fault. Connect CHG to the desired logic voltage rail using a 1kΩ to 100kΩ resistor, or use with an
LED for visual indication.
OUT
10, 11
10, 11
O
System Supply Output. OUT provides a regulated output when the input is below the OVP threshold and
above the regulation voltage. When the input is out of the operation range, OUT is connected to VBAT
except when SYSOFF is high. Connect OUT to the system load. Bypass OUT to VSS with a 4.7μF to
47μF ceramic capacitor.
ILIM
12
12
O
Adjustable Current Limit Programming Input. Connect a 1.07kΩ to 7.5kΩ resistor from ILIM to VSS to
program the maximum input current (EN2=1, EN1=0). The input current includes the system load and the
battery charge current. Leaving ILIM unconnected disables all charging.
IN
13
13
I
Input Power Connection. Connect IN to the external DC supply (AC adapter or USB port). The input
operating range is 4.35V to 6.6V. The input accepts voltages up to 26V without damage, but operation is
suspended. Bypass IN to VS with a 1μF to 10μF ceramic capacitor.
TMR
14
14
I
Timer Programming Input. TMR controls the pre-charge and fast-charge safety timers. Connect TMR to
VSS to disable all safety timers. Connect a 18kΩ to 72kΩ resistor between TMR and VSS to program the
timers to a desired length. Leave TMR unconnected to set the timers to the default values.
TS
4
Submit Documentation Feedback
Copyright © 2009–2019, Texas Instruments Incorporated
Product Folder Links: BQ24072T BQ24075T BQ24079T
BQ24072T, BQ24075T, BQ24079T
www.ti.com
SLUS937C – DECEMBER 2009 – REVISED DECEMBER 2019
Pin Functions (continued)
PIN
NUMBER
NAME
DESCRIPTION
BQ24072T
BQ24075T
BQ24079T
I/O
SYSOFF
–
15
I
System Enable Input. Connect SYSOFF high to turn off the FET connecting the battery to the system
output. When an adapter is connected, charge is also disabled. Connect SYSOFF low for normal
operation. SYSOFF is internally pulled up to VBAT through a large resistor (~5MΩ). Do not leave
SYSOFF unconnected to ensure proper operation.
TD
15
–
I
Termination Disable Input. Connect TD high to disable charger termination. Connect TD to VSS to
enable charger termination. TD is checked during startup only and cannot be changed during operation.
See the TD section in this datasheet for a description of the behavior when termination is disabled. TD is
internally pulled down to VSS with ~285 kΩ. Do not leave TD unconnected to ensure proper operation.
ISET
16
16
I/O
Fast Charge Current Programming Input. Connect a 590 Ω to 3 kΩ resistor from ISET to VSS to program
the fast charge current level. Charging is disabled if ISET is left unconnected. While charging, the voltage
ISET reflects the actual charging current and can be used to monitor charge current. See the Charge
Current Translator section of this datasheet for more details.
Thermal
Pad
–
--
–
There is an internal electrical connection between the exposed thermal pad and the VSS pin of the
device. The thermal pad must be connected to the same potential as the VSS pin on the printed circuit
board. Do not use the thermal pad as the primary ground input for the device. VSS must be connected to
ground at all times.
Table 1. EN1/EN2 Settings
EN2
EN1
MAXIMUM INPUT CURRENT INTO IN
0
0
100 mA. USB100 mode
0
1
500 mA. USB500 mode
1
0
Set by external resistor from ILIM to VSS
1
1
Standby (USB suspend mode)
Copyright © 2009–2019, Texas Instruments Incorporated
Product Folder Links: BQ24072T BQ24075T BQ24079T
Submit Documentation Feedback
5
BQ24072T, BQ24075T, BQ24079T
SLUS937C – DECEMBER 2009 – REVISED DECEMBER 2019
www.ti.com
8 Specifications
8.1 Absolute Maximum Ratings (1)
(2)
over operating free-air temperature range (unless otherwise noted)
Input voltage
Input current
MIN
MAX
UNIT
IN (with respect to VSS)
–0.3
28
V
BAT (with respect to VSS)
–0.3
5
V
OUT, EN1, EN2, CE, TS, ISET, PGOOD, CHG, ILIM, VREF,
ITERM, SYSOFF, TD (with respect to VSS)
–0.3
7
V
IN
Output current (Continuous)
Output sink current
1.6
A
OUT
5
A
BAT (Discharge mode)
5
A
BAT (Charging mode)
1.5
A
CHG, PGOOD
15
mA
Junction temperature, TJ
–40
150
°C
Storage temperature , Tstg
–65
150
°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.
The IC operational charging life is reduced to 20,000 hours, when charging at 1.5A and 125°C. The thermal regulation feature reduces
charge current if the IC’s junction temperature reaches 125°C; thus without a good thermal design the maximum programmed charge
current may not be reached.
8.2 ESD Ratings
V(ESD)
(1)
(2)
Electrostatic discharge
VALUE
UNIT
Human body model (HBM), per ANSI/ESDA/JEDEC JS-001, all pins (1)
±2000
V
Charged device model (CDM), per JEDEC specification JESD22-C101,
all pins (2)
±500
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
8.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
VIN
MIN
MAX
IN voltage range
4.35
26
UNITS
V
IN operating voltage range
4.35
6.4
V
IIN
Input current, IN pin
1.5
A
IOUT
Current, OUT pin
4.5
A
IBAT
Current, BAT pin (Discharging)
4.5
A
(1)
A
125
°C
ICHG
Current, BAT pin (Charging)
TJ
Junction Temperature
RILIM
Maximum input current programming resistor
1.07
7.5
kΩ
RISET
Fast-charge current programming resistor (2)
590
3000
Ω
RITERM
Termination current programming resistor
0
15
kΩ
RTMR
Timer programming resistor
18
72
kΩ
(1)
(2)
6
1.5
0
The IC operational charging life is reduced to 20,000 hours, when charging at 1.5A and 125°C. The thermal regulation feature reduces
charge current if the IC’s junction temperature reaches 125°C; thus without a good thermal design the maximum programmed charge
current may not be reached.
Use a 1% tolerance resistor RISET to avoid issues with the RISET short test when using the maximum charge current setting.
Submit Documentation Feedback
Copyright © 2009–2019, Texas Instruments Incorporated
Product Folder Links: BQ24072T BQ24075T BQ24079T
BQ24072T, BQ24075T, BQ24079T
www.ti.com
SLUS937C – DECEMBER 2009 – REVISED DECEMBER 2019
8.4 Thermal Information
RGT [VQFN]
THERMAL METRIC (1)
16 PINS
UNIT
RθJA
Junction-to-ambient thermal resistance
45.8
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
53.6
°C/W
RθJB
Junction-to-board thermal resistance
18.1
°C/W
ψJT
Junction-to-top characterization parameter
1.1
°C/W
ψJB
Junction-to-board characterization parameter
18.0
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
5.2
°C/W
(1)
For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.
8.5 Electrical Characteristics
Over junction temperature range (0°C < TJ < 125°C) and the recommended supply voltage range (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
3.3
MAX
UNIT
INPUT
VUVLO
Under-voltage lock-out
VIN: 0V → 4V
3.2
VHYS-UVLO
Hysteresis on UVLO
VIN: 4V → 0V
200
VIN-DT
Input power detection threshold
(Input power detected if VIN > VBAT + VIN-DT)
VBAT = 3.6V, VIN: 3.5V → 4V
55
VHYS-INDT
Hysteresis on VIN-DT
VBAT = 3.6V, VIN: 4V → 3.5V
20
tDGL(PGOOD)
Deglitch time, input power detected
status
Time measured from VIN: 0V → 5V,
1μs rise-time to PGOOD = LO
VOVP
Input overvoltage protection threshold
VIN: 5V → 7V
VHYS-OVP
Hysteresis on OVP
VIN: 7V → 5V
tBLK(OVP)
Input over-voltage blanking time
tREC(OVP)
80
V
mV
140
mV
mV
1.2
6.4
6.6
ms
6.8
V
240
mV
50
μs
1.2
ms
1.3
mA
520
mV
Time measured from VIN: 11V → 5V 1μs
fall-time to PGOOD = LO
Input over-voltage recovery time
3.4
300
ILIM, ISET SHORT CIRCUIT TEST
ISC
Current source
VSC
QUIESCENT CURRENT
IBAT(PDWN)
Sleep current into BAT pin
IIN(STDBY)
Standby current into IN pin
ICC
Active supply current, IN pin
CE = LO or HI, input power not detected, no load
on OUT pin
6.5
μA
EN1= HI, EN2=HI, VIN ≤ 6V
50
EN1= HI, EN2=HI, VIN > 6V
200
CE = LO, VIN = 6V, no load on OUT pin,
VBAT > VBAT(REG), (EN1,EN2)≠(HI,HI)
1.5
mA
300
475
mV
50
100
mV
μA
POWER PATH
VDO(IN-OUT)
VDO(BATOUT)
VO(REG)
VIN – VOUT
VIN = 4.3V, IIN = 1A, VBAT = 4.2V
VBAT – VOUT
IOUT = 1A, VIN = 0V, VBAT > 3V
OUT pin voltage regulation
(BQ24072T)
OUT pin voltage regulation
(BQ24075T, BQ24079T)
IIN-MAX
Maximum input current
VIN > VOUT + VDO(IN-OUT) , VBAT< 3.2 V
3.3
3.4
3.5
VIN > VOUT + VDO(IN-OUT) , VBAT ≥ 3.2 V
VBAT +
150 mV
VBAT +
225 mV
VBAT +
270 mV
VIN > VOUT + VDO(IN-OUT)
5.4
5.5
5.6
EN1 = LO, EN2 = LO
90
95
100
mA
EN1 = HI, EN2 = LO
450
475
500
mA
EN2 = HI, EN1 = LO
KILIM/RIL
A
IM
ILIM ≥ 500mA
1500
1600
1700
200mA < ILIM < 500mA
1330
1512
1700
KILIM
Maximum input current factor
IIN-MAX
Programmable input current limit
range
EN2 = HI, EN1 = LO, RILIM = 8kΩ to 1.1kΩ
200
VIN-DPM
Input voltage threshold when input
current is reduced
EN2 = LO, EN1 = X
4.35
Copyright © 2009–2019, Texas Instruments Incorporated
Product Folder Links: BQ24072T BQ24075T BQ24079T
4.5
V
AΩ
1500
mA
4.63
V
Submit Documentation Feedback
7
BQ24072T, BQ24075T, BQ24079T
SLUS937C – DECEMBER 2009 – REVISED DECEMBER 2019
www.ti.com
Electrical Characteristics (continued)
Over junction temperature range (0°C < TJ < 125°C) and the recommended supply voltage range (unless otherwise noted)
PARAMETER
TEST CONDITIONS
BQ24072T
Output voltage threshold when
charging current is reduced
VDPPM
MIN
TYP
MAX
VO(REG)
–180 mV
VO(REG)
–100 mV
VO(REG)
–30 mV
4.2
4.3
4.4
BQ24075T, BQ24079T
UNIT
V
VBSUP1
Enter battery supplement mode
VOUT falling, Supplement mode entered when
VOUT < VBSUP1
VBAT –
40mV
V
VBSUP2
Exit battery supplement mode
VOUT rising, Supplement mode exited when VOUT
> VBSUP2
VBAT –
20mV
V
VO(SC1)
Output short-circuit detection
threshold, power-on
0.8
0.9
1.0
V
VO(SC2)
Output short-circuit detection
threshold, supplement mode VBAT –
VOUT > VO(SC2) indicates short-circuit
200
250
300
mV
tDGL(SC2)
Deglitch time, supplement mode short
circuit
tREC(SC2)
Recovery time, supplement mode
short circuit
250
μs
60
ms
BATTERY CHARGER
IBAT(SC)
Source current for BAT pin shortcircuit detection
VBAT(SC)
BAT pin short-circuit detection
threshold
VBAT(REG)
Battery charge voltage
VLOWV
Pre-charge to fast-charge transition
threshold
tDGL1(LOWV)
Deglitch time on pre-charge to fastcharge transition
25
ms
tDGL2(LOWV)
Deglitch time on fast-charge to precharge transition
25
ms
ICHG
Battery fast charge current range
VBAT(REG) > VBAT > VLOWV, VIN = 5V, CE = LO,
EN1= LO, EN2 = HI
ICHG
Battery fast charge current
CE = LO, EN1= LO, EN2 = HI, VBAT > VLOWV,
VIN = 5V, IIN-MAX > ICHG, no load on OUT pin,
thermal loop not active, DPM loop not active
KISET
Fast charge current factor
IPRECHG
Pre-charge current
kPRECHG
Pre-charge current factor
BQ24072T, BQ24075T
BQ24079T
tDGL(TERM)
7.5
11
mA
1.6
1.8
2.0
V
4.16
4.20
4.24
4.059
4.100
4.141
2.9
3
3.1
300
Recharge detection threshold
tDGL(RCH)
Deglitch time, recharge threshold
detected
tDGL(NO-IN)
Delay time, input power loss to
charger turn-off
IBAT(DET)
Sink current for battery detection
tDET
Battery detection timer
890
975
88
106
CE = LO, (EN1,EN2)≠(LO,LO),
VBAT > VRCH, t < tMAXCH, VIN = 5V, DPM loop not
active, thermal loop not active
0.09×ICHG
0.1×ICHG
0.11×ICHG
CE = LO, (EN1,EN2)=(LO,LO),
VBAT > VRCH, t < tMAXCH, VIN = 5V, DPM loop not
active, thermal loop not active
0.027×ICHG
0.033×ICHG
0.040×ICHG
VBAT(REG)
–140mV
VBAT(REG)
–100mV
25
5
V
mA
AΩ
A
70
VBAT = 3.6V. Time measured from VIN:
5V → 3.3V 1μs fall-time
V
A
KPRECHG /RISET
Deglitch time, termination detected
VRCH
1500
KISET/RISET
797
Charge current value for termination
detection threshold
ITERM
4
ms
VBAT(REG)
–60mV
V
62.5
ms
20
ms
7.5
10
250
mA
ms
BATTERY CHARGING TIMERS
tPRECHG
Pre-charge safety timer value
TMR = floating
1440
1800
2160
s
tMAXCH
Charge safety timer value
TMR = floating
14400
18000
21600
s
tPRECHG
Pre-charge safety timer
value(externally set)
18kΩ < RTMR < 72kΩ
8
Submit Documentation Feedback
RTMR x KTMR
s
Copyright © 2009–2019, Texas Instruments Incorporated
Product Folder Links: BQ24072T BQ24075T BQ24079T
BQ24072T, BQ24075T, BQ24079T
www.ti.com
SLUS937C – DECEMBER 2009 – REVISED DECEMBER 2019
Electrical Characteristics (continued)
Over junction temperature range (0°C < TJ < 125°C) and the recommended supply voltage range (unless otherwise noted)
PARAMETER
TEST CONDITIONS
tMAXCH
Charge safety timer value (externally
set)
KTMR
Timer factor
18kΩ < RTMR < 72kΩ
MIN
TYP
MAX
10 x RTMR x KTMR
UNIT
s
35
45
55
s / kΩ
12
12.5
13
% of
VIN
BATTERY – PACK NTC MONITOR
VHOT
High temperature trip point
Battery charging
VHYS(HOT)
Hysteresis on high trip point
Battery charging
VCOLD
Low temperature trip point
Battery charging
VHYS(COLD)
Hysteresis on low trip point
Battery charging
1
% of
VIN
tDGL(TS)
Deglitch time, pack temperature fault
detection
Battery charging
50
ms
% of
VIN
1
24.5
25
25.5
% of
VIN
THERMAL REGULATION
TJ(REG)
Temperature Regulation Limit
125
°C
TJ(OFF)
Thermal shutdown temperature
155
°C
TJ(OFF-HYS)
Thermal shutdown hysteresis
20
°C
LOGIC LEVELS ON EN1, EN2, CE, SYSOFF, TD
VIL
Logic LOW input voltage
0
0.4
VIH
Logic HIGH input voltage
1.4
6.0
V
V
IIL
1
μA
IIH
10
μA
0.4
V
LOGIC LEVELS ON PGOOD, CHG
VOL
Output LOW voltage
ISINK = 5 mA
Copyright © 2009–2019, Texas Instruments Incorporated
Product Folder Links: BQ24072T BQ24075T BQ24079T
Submit Documentation Feedback
9
BQ24072T, BQ24075T, BQ24079T
SLUS937C – DECEMBER 2009 – REVISED DECEMBER 2019
www.ti.com
8.6 Typical Characteristics
VIN = 6 V, EN1 = 1, EN2 = 0, TA = 25°C, unless otherwise noted.
600
0.7
500
0.6
Dropout Voltage - VIN-VOUT
IBAT - mA
IL = 1 A
400
300
200
100
0
0.5
0.4
0.3
0.2
0.1
120
125
130
135
Temperature - oC
140
0
145
Figure 1. Thermal Regulation
0
25
100
50
75
TJ - Junction Temperature - °C
125
Figure 2. Dropout Voltage vs Temperature
4.6
120
VIN = 5 V
IL = 1 A
4.4
80
VO - Output Voltage - V
Dropout Voltage - VBAT-VOUT
100
VBAT = 3 V
60
VBAT = 3.9 V
40
20
3.8
3.6
3.4
3
0
50
75
100
25
TJ - Junction Temperature - °C
2
125
Figure 3. Dropout Voltage vs Temperature
2.5
3
3.5
4
VBAT - Battery Voltage - V
4.5
Figure 4. BQ24072T Output Regulation Voltage vs Battery
Voltage
5.75
3.80
VIN = 5 V,
VBAT = 3.5 V,
IL = 1 A
3.76
5.65
3.74
3.72
3.70
3.68
3.66
5.60
5.55
5.50
5.45
5.40
3.64
5.35
3.62
5.30
3.60
0
25
VIN = 6 V,
IL = 1 A
5.70
VO - Output Voltage - V
3.78
VO - Output Voltage - V
4
3.2
0
50
75
100
125
TJ - Junction Temperature - °C
Figure 5. BQ24072T Output Regulation Voltage vs
Temperature
10
4.2
Submit Documentation Feedback
5.25
0
25
50
75
100
TJ - Junction Temperature - °C
125
Figure 6. Output Regulation Voltage vs Temperature
Copyright © 2009–2019, Texas Instruments Incorporated
Product Folder Links: BQ24072T BQ24075T BQ24079T
BQ24072T, BQ24075T, BQ24079T
www.ti.com
SLUS937C – DECEMBER 2009 – REVISED DECEMBER 2019
Typical Characteristics (continued)
4.210
4.11
4.205
4.105
VBAT - Regulation Voltage - V
VBAT - Regulation Voltage - V
VIN = 6 V, EN1 = 1, EN2 = 0, TA = 25°C, unless otherwise noted.
4.200
4.195
4.190
4.185
4.180
0
4.1
4.095
4.09
4.085
4.08
5
10
15
20
25
0
30
TJ - Junction Temperature - °C
Figure 7. BQ24075T BAT Regulation Voltage vs
Temperature
800
RILIM
6.6 V
700
6.65
ILIM - Input Current - mA
VOVP - Output Voltage Threshold - V
30
Figure 8. BQ24079T Battery Regulation Voltage vs
Temperature
6.70
VI Rising
6.60
6.55
VI Falling
6.50
600
500
USB500
400
300
200
USB100
100
6.45
0
0
25
50
75
100
TJ - Junction Temperature - °C
5
125
Figure 9. Overvoltage ProtectionThreshold vs Temperature
6
7
8
9
VI - Input Voltage - V
10
Figure 10. Input Current Limit vs Input Voltage
310
1.05
RISET = 900 W
RISET = 3 kW
IBAT - Fast Charge Current - A
IBAT - Fast Charge Current - A
5
10
15
20
25
TJ - Junction Temperature - °C
1.03
1.01
0.99
0.97
0.95
305
300
295
290
285
280
3
3.2
3.6
3.8
4
3.4
VBAT - Battery Voltage - V
4.2
Figure 11. Fastcharge Current vs Battery Voltage
3
3.2
3.4
3.6
3.8
4
VBAT - Battery Voltage - V
4.2
Figure 12. Fastcharge Current vs Battery Voltage
Copyright © 2009–2019, Texas Instruments Incorporated
Product Folder Links: BQ24072T BQ24075T BQ24079T
Submit Documentation Feedback
11
BQ24072T, BQ24075T, BQ24079T
SLUS937C – DECEMBER 2009 – REVISED DECEMBER 2019
www.ti.com
Typical Characteristics (continued)
VIN = 6 V, EN1 = 1, EN2 = 0, TA = 25°C, unless otherwise noted.
31.5
105
RISET = 900 W
RISET = 3 kW
31
103
IBAT - Precharge Current - A
IBAT - Precharge Current - A
104
102
101
100
99
98
97
30.5
30
29.5
29
96
28.5
95
2
12
2.2
2.4
2.6
2.8
3
VBAT - Battery Voltage - V
2.2
2.4
2.6
2.8
VBAT - Battery Voltage - V
Figure 13. Fastcharge Current vs Battery Voltage
Figure 14. Precharge Current vs Battery Voltage
Submit Documentation Feedback
2
3
Copyright © 2009–2019, Texas Instruments Incorporated
Product Folder Links: BQ24072T BQ24075T BQ24079T
BQ24072T, BQ24075T, BQ24079T
www.ti.com
SLUS937C – DECEMBER 2009 – REVISED DECEMBER 2019
9 Detailed Description
9.1 Overview
The BQ2407x devices are integrated Li-Ion linear chargers and system power path management devices
targeted at space-limited portable applications. The device powers the system while simultaneously and
independently charging the battery. This feature reduces the number of charge and discharge cycles on the
battery, allows for proper charge termination and enables the system to run with a defective or absent battery
pack. It also allows instant system turn-on even with a totally discharged battery. The input power source for
charging the battery and running the system can be an AC adapter or a USB port. The devices feature Dynamic
Power Path Management (DPPM), which shares the source current between the system and battery charging,
and automatically reduces the charging current if the system load increases. When charging from a USB port,
the input dynamic power management (VIN-DPM) circuit reduces the input current if the input voltage falls below a
threshold, preventing the USB port from crashing. The power-path architecture also permits the battery to
supplement the system current requirements when the adapter cannot deliver the peak system currents.
9.2 Functional Block Diagram
250mV
VO(SC1)
V BAT
OUT-SC1
t DGL(SC2)
OUT- SC2
Q1
IN
OUT
EN2
Short Detect
225mV
Precharge
VIN-DPM
USB100
USB5 00
ISET
2.25V
Fastcharge
TJ
ILIM
VREF- ILIM
USB-susp
TJ(REG)
Short Detect
V DPPM
V O(REG)
Q2
VOUT
EN2
EN1
V BAT (REG)
BAT
VBAT
V OUT
CHARGEPUMP
SYSOFF
40mV
Supplement
V LOWV
225mV)
V BAT(SC)
tDGL(RCH)
tDGL2(LOWV)
VIN
tDGL1(LOWV)
tDGL(TE RM)
V RCH
VIN
BAT-SC
V BAT + VIN-DT
tDGL(NO-IN)
tDGL(PGOOD)
V UVLO
VCOLD
TS
t DGL(TS)
Charge Control
V HOT
V OVP
tBLK(OVP)
EN1
EN2
USB Suspend
CE
Halt timers
CHG
V IPRECHG
VICHG
V ISET
Reset timers
PGOOD
Dynamically
Controlled
Oscillator
TMR
Fast- Charge
Timer
Timer fault
Pre- Charge
Timer
Copyright © 2009–2019, Texas Instruments Incorporated
Product Folder Links: BQ24072T BQ24075T BQ24079T
Submit Documentation Feedback
13
BQ24072T, BQ24075T, BQ24079T
SLUS937C – DECEMBER 2009 – REVISED DECEMBER 2019
www.ti.com
9.3 Feature Description
9.3.1 Undervoltage Lockout (UVLO)
The BQ2407X family remains in power down mode when the input voltage at the IN pin is below the
undervoltage threshold (UVLO). During the power down mode the host commands at the control inputs (CE, EN1
and EN2) are ignored. The Q1 FET connected between IN and OUT pins is off, and the status outputs, CHG and
PGOOD, are high impedance. The Q2 FET that connects BAT to OUT is ON. (If SYSOFF is high, Q2 is off).
During power down mode, the VOUT(SC2) circuitry is active and monitors for overload conditions on OUT.
9.3.2 Overvoltage Protection (OVP)
The BQ2407xT accepts inputs up to 28V without damage. Additionally, an overvoltage protection (OVP) circuit is
implemented that shuts off the internal LDO and discontinues charging when VIN > VOVP for a period longer than
tDGL(OVP). When in OVP, the system output (OUT) is connected to the battery and PGOOD is high impedance.
Once the OVP condition is removed, a new power on sequence starts (See the POWER ON section). The safety
timers are reset and a new charge cycle will be indicated by the CHG output.
9.3.3 Dynamic Power-Path Management
The BQ2407xT features an OUT output that powers the external load connected to the battery. This output is
active whenever a source is connected to IN or BAT. The following sections discuss the behavior of OUT with a
source connected to IN to charge the battery and a battery source only.
9.3.4 Battery Charging
Set CE low to initiate battery charging. First, the device checks for a short-circuit on the BAT pin by sourcing
IBAT(SC) to the battery and monitoring the voltage. When the BAT voltage exceeds VBAT(SC), the battery charging
continues. The battery is charged in three phases: conditioning pre-charge, constant current fast charge (current
regulation) and a constant voltage tapering (voltage regulation). In all charge phases, an internal control loop
monitors the IC junction temperature and reduces the charge current if an internal temperature threshold is
exceeded.
Figure 15. Typical Charging Cycle
14
Submit Documentation Feedback
Copyright © 2009–2019, Texas Instruments Incorporated
Product Folder Links: BQ24072T BQ24075T BQ24079T
BQ24072T, BQ24075T, BQ24079T
www.ti.com
SLUS937C – DECEMBER 2009 – REVISED DECEMBER 2019
Feature Description (continued)
Figure 15 illustrates a normal Li-Ion charge cycle using the BQ2407xT. In the pre-charge phase, the battery is
charged at with the pre-charge current (IPRECHG). Once the battery voltage crosses the VLOWV threshold, the
battery is charged with the fast-charge current (ICHG). As the battery voltage reaches VBAT(REG), the battery is held
at a constant voltage of VBAT(REG) and the charge current tapers off as the battery approaches full charge. When
the battery current reaches ITERM, the CHG pin indicates charging done by going high-impedance.
Note that termination detection is disabled whenever the charge rate is reduced because of the actions of the
thermal loop, the DPPM loop or the VIN-DPM loop.
The value of the fast-charge current is set by the resistor connected from the ISET pin to VSS, and is given by
Equation 1.
ICHG = KISET / RISET
(1)
The charge current limit is adjustable up to 1.5A. The valid resistor range is 590Ω to 3 kΩ. Note that if ICHG is
programmed as greater than the input current limit, the battery will not charge at the rate of ICHG, but at the
slower rate of IIN(MAX) (minus the load current on the OUT pin, if any). In this case, the charger timers will be
proportionately slowed down.
9.3.5 Charge Current Translator
When the charger is enabled, internal circuits generate a current proportional to the charge current at the ISET
input. The current out of ISET is 1/400 (±10%) of the charge current. This current, when applied to the external
charge current programming resistor, RISET, generates an analog voltage that can be monitored by an external
host to calculate the current sourced from BAT.
VISET = ICHARGE / 400 × RISET
(2)
Copyright © 2009–2019, Texas Instruments Incorporated
Product Folder Links: BQ24072T BQ24075T BQ24079T
Submit Documentation Feedback
15
BQ24072T, BQ24075T, BQ24079T
SLUS937C – DECEMBER 2009 – REVISED DECEMBER 2019
www.ti.com
Feature Description (continued)
Begin Charging
Battery short detected
?
Yes
No
Start Precharge
/CHG= Low
No
No
V BAT > VLOWV
tPRECHARGE
Elapsed?
Yes
End Charge
Flash/CHG
Start Fastcharge
ICHARGE set by ISET
No
No
IBAT < ITERM
tFASTCHARGE
Elapsed?
Yes
End Charge
Flash/CHG
Charge Done
/CHG= Hi-Z
TD= Low
(’72, ’73 Only)
(’74, ’75= YES)
No
Yes
Termination Reached
BATTFET Off
Wait for VBAT < V RCH
No
VBAT < V RCH
Yes
Run Battery Detection
No
Battery Detected
?
Yes
Figure 16. Battery Charging Flow Diagram
16
Submit Documentation Feedback
Copyright © 2009–2019, Texas Instruments Incorporated
Product Folder Links: BQ24072T BQ24075T BQ24079T
BQ24072T, BQ24075T, BQ24079T
www.ti.com
SLUS937C – DECEMBER 2009 – REVISED DECEMBER 2019
Feature Description (continued)
9.3.6 Battery Detection and Recharge
The BQ2407xT automatically detects if a battery is connected or removed. Once a charge cycle is complete, the
battery voltage is monitored. When the battery voltage falls below VRCH, the battery detection routine is run.
During battery detection, current (IBAT(DET)) is pulled from the battery for a duration tDET to see if the voltage on
BAT falls below VLOWV. If not, charging begins. If it does, then it indicates that the battery is missing or the
protector is open. Next, the precharge current is applied for tDET to close the protector if possible. If VBAT < VRCH,
then the protector is closed and charging is initiated. If VBAT > VRCH, then the battery is determined to be missing
and the detection routine continues.
9.3.7 Termination Disable (TD Input, BQ24072T)
The BQ24072T contains a TD input that allows termination to be enabled/ disabled. Connect TD to a logic high
to disable charge termination. When termination is disabled, the device goes through the pre-charge, fast-charge
and CV phases, then remains in the CV phase. During the CV phase, the charger maintains the output voltage at
BAT equal to VBAT(REG), and charging current does not terminate. The charge current is set by ICHG or IINmax,
whichever is less. Battery detection is not performed. The CHG output is high impedance once the current falls
below ITERM and does not go low until the input power or CE are toggled. When termination is disabled, the precharge and fast-charge safety timers are also disabled.
9.3.8 Battery Disconnect (SYSOFF Input)
The BQ24075T and BQ24079T feature a SYSOFF input that allows the user to turn the FET Q2 off and
disconnect the battery from the OUT pin. This is useful for disconnecting the system load from the battery,
factory programming where the battery is not installed or for host side impedance track fuel gauging, such as
BQ27500, where the battery open circuit voltage level must be detected before the battery charges or
discharges. The CHG output remains low when SYSOFF is high. Connect SYSOFF to VSS, to turn Q2 on for
normal operation. SYSOFF is internally pulled to VBAT through ~5 MΩ resistor.
9.3.9 Dynamic Charge Timers (TMR Input)
The BQ2407xT devices contain internal safety timers for the pre-charge and fast-charge phases to prevent
potential damage to the battery and the system. The timers begin at the start of the respective charge cycles.
The timer values are programmed by connecting a resistor from TMR to VSS. The resistor value is calculated
using the following equation:
tPRECHG = KTMR × RTMR
tMAXCHG = 10 × KTMR × RTMR
Leave TMR unconnected to select the internal default timers. Disable the timers by connecting TMR to VSS.
Note that timers are suspended when the device is in thermal shutdown, and the timers are slowed proportionally
to the charge current when the device enters thermal regulation.
1. During the fast charge phase, several events increase the timer durations.
2. The system load current activates the DPPM loop which reduces the available charging current
3. The input current is reduced because the input voltage has fallen to VIN-DPM
4. The device has entered thermal regulation because the IC junction temperature has exceeded TJ(REG)
During each of these events, the internal timers are slowed down proportionately to the reduction in charging
current. For example, if the charging current is reduced by half for two minutes, the timer clock is reduced to half
the frequency and the counter counts half as fast resulting in only one minute of "counting" time.
If the precharge timer expires before the battery voltage reaches VLOWV, the BQ2407xT indicates a fault
condition. Additionally, if the battery current does not fall to ITERM before the fast charge timer expires, a fault is
indicated. The CHG output flashes at approximately 2 Hz to indicate a fault condition. The fault condition is
cleared by toggling CE or the input power, entering/ exiting USB suspend mode, or an OVP event.
Copyright © 2009–2019, Texas Instruments Incorporated
Product Folder Links: BQ24072T BQ24075T BQ24079T
Submit Documentation Feedback
17
BQ24072T, BQ24075T, BQ24079T
SLUS937C – DECEMBER 2009 – REVISED DECEMBER 2019
www.ti.com
Feature Description (continued)
9.3.10 Status Indicators (PGOOD, CHG)
The BQ2407xT contains two open-drain outputs that signal its status. The PGOOD output signals when a valid
input source is connected. PGOOD is low when (VBAT + VIN(DT)) < VIN < VOVP. When the input voltage is outside
of this range, PGOOD is high impedance.
The charge cycle after power-up, CE going low, or exiting OVP is indicated with the CHG output on (low - LED
on), whereas all refresh (subsequent) charges will result in the CHG output off (open – LED off). In addition, the
CHG signals timer faults by flashing at approximately 2 Hz.
Table 2. PGOOD Status Indicator
INPUT STATE
PGOOD OUTPUT
VIN < VUVLO
Hi impedance
VUVLO < VIN < VIN(DT)
Hi impedance
VIN(DT) < VIN < VOVF
Low
VIN < VOVP
Hi impedance
Table 3. CHG Status Indicator
CHARGE STATE
Charging
Charging suspended by thermal loop, or DPPM loop
Safety timers expired
CHG OUTPUT
Low (for first charge cycle)
Flashing at 2 Hz
Charging done
Recharging after termination
IC disabled or no valid input power
Hi impedance
Battery absent
9.3.11 Thermal Regulation and Thermal Shutdown
The BQ2407xT contain a thermal regulation loop that monitors the die temperature. If the temperature exceeds
TJ(REG), the device automatically reduces the charging current to prevent the die temperature from increasing
further. In some cases, the die temperature continues to rise despite the operation of the thermal loop,
particularly under high VIN and heavy OUT system load conditions. Under these conditions, if the die temperature
increases to TJ(OFF), the input FET Q1 is turned OFF. FET Q2 is turned ON to ensure that the battery still powers
the load on OUT. Once the device die temperature cools by TJ(OFF-HYS), the input FET Q1 is turned on and the
device returns to thermal regulation. Continuous overtemperature conditions result in a "hiccup" mode. During
thermal regulation, the safety timers are slowed down proportionately to the reduction in current limit.
Note that this feature monitors the die temperature of the BQ2407xT. This is not synonymous with ambient
temperature. Self heating exists due to the power dissipated in the IC because of the linear nature of the battery
charging algorithm and the LDO associated with OUT. A modified charge cycle with the thermal loop active is
shown in Figure 17. Battery termination is disabled during thermal regulation.
18
Submit Documentation Feedback
Copyright © 2009–2019, Texas Instruments Incorporated
Product Folder Links: BQ24072T BQ24075T BQ24079T
BQ24072T, BQ24075T, BQ24079T
www.ti.com
SLUS937C – DECEMBER 2009 – REVISED DECEMBER 2019
PRECHARGE
THERMAL
REGULATION
CC FAST
CHARGE
CV TAPER
DONE
VO(REG)
IO(CHG)
Battery Voltage
Battery Current
V(LOWV)
HI-z
I(PRECHG)
I(TERM)
TJ(REG)
IC Junction Temperature, TJ
Figure 17. Charge Cycle Modified by Thermal Loop
9.3.12 Battery Pack Temperature Monitoring
The BQ2407xT features an external battery pack temperature monitoring input. The TS input connects to the
NTC thermistor in the battery pack to monitor battery temperature and prevent dangerous over-temperature
conditions. During charging, the voltage at TS is continuously monitored. If, at any time, the voltage at TS is
outside of the operating range (VCOLD to VHOT), charging is suspended. The timers maintain their values but
suspend counting. When the voltage measured at TS returns to within the operation window, charging is
resumed and the timers continue counting. When charging is suspended due to a battery pack temperature fault,
the CHG output remains low and continues to indicate charging.
VIN
R6 =
-1
VCOLD
1
1
+
R 7 RCOLD
(3)
é 1
1 ù
VIN ´ RCOLD ´ RHOT ´ ê
ú
VCOLD VHOT û
ë
R7 =
é V
ù
é V
ù
RHOT ´ ê IN - 1ú - RCOLD ´ ê IN - 1ú
ëVHOT
û
ëVCOLD
û
Copyright © 2009–2019, Texas Instruments Incorporated
Product Folder Links: BQ24072T BQ24075T BQ24079T
(4)
Submit Documentation Feedback
19
BQ24072T, BQ24075T, BQ24079T
SLUS937C – DECEMBER 2009 – REVISED DECEMBER 2019
www.ti.com
Where:
VCOLD = 0.25 X VIN
VHOT = 0.125 X VIN
RHOT is the expected thermistor resistance at the programmed hot threshold, RCOLD is the expected thermistor
resistance at the programmed cold threshold. If the value of R6 is less than 100 kΩ, R8 must be added to protect
the IC from 28V inputs. If R6 is greater than 100 kΩ, R8 does not need to be used.
Adapter
IN
R6
V COLD
+
TS
R8
PACK
TEMP
+
Not necessary
in all
applications
VHOT
+
R7
PACK
-
+
BQ240xT
Figure 18. NTC Monitoring Function
For applications that do not require the TS monitoring function, set R6 = 200 kΩ and R7 = 49.9 kΩ to set the TS
voltage at a valid level and maintain charging.
9.4 Device Functional Modes
9.4.1 Input Source Connected (Adapter or USB)
With a source connected, the dynamic power-path management (DPPM) circuitry of the BQ2407xT monitors the
input current continuously. The OUT output for the BQ24075T and BQ24079T is regulated to a fixed voltage
(VO(REG)). For the BQ24072T, OUT is regulated to 225 mV above the voltage at BAT. If the BAT voltage is less
than 3.2 V, OUT is clamped to 3.4 V. This allows for proper startup of the system load even with a discharged
battery. The current into IN is shared between charging the battery and powering the system load at OUT. The
BQ2407xT has internal selectable current limits of 100 mA (USB100) and 500 mA (USB500) for charging from
USB ports, as well as a resistor-programmable input current limit.
The BQ2407xT is USB IF compliant for the inrush current testing. The USB spec allows up to 10 μF to be hard
started, which establishes 50μC as the maximum inrush charge value when exceeding 100 mA. The input
current limit for the BQ2407xT prevents the input current from exceeding this limit, even with system
capacitances greater than 10 μF. Note that the input capacitance to the device must be selected small enough to
prevent a violation (
工商网监
湘ICP备2023018690号
