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bq24308
SLUS977B – SEPTEMBER 2009 – REVISED AUGUST 2015
bq24308 Overvoltage and Overcurrent Protection IC and
Li+ Charger Front-End Protection IC
1 Features
3 Description
•
The bq24308 device is a highly integrated circuit (IC)
designed to provide protection to Li-ion batteries from
failures of the charging circuit. The device
continuously monitors the input voltage, the input
current, and the battery voltage. In case of an input
overvoltage condition, the device immediately
removes power from the charging circuit by turning
off an internal switch. In the case of an overcurrent
condition, it limits the system current to a safe value
for a blanking duration before turning the switch off.
Battery voltage may also be monitored and if the
battery voltage exceeds the specified value the
internal switch is turned off. Additionally, the device
also monitors its own die temperature and switches
off if it becomes too hot.
1
•
•
•
•
•
•
Provides Protection for Three Variables:
– Input Overvoltage
– Input Overcurrent with Current Limiting
– Battery Overvoltage
Maximum Input Voltage of 30 V
Supports Up to 1.5-A Input Current
Robust Against False Triggering Due to Current
Transients
Thermal Shutdown
LDO Mode Voltage Regulation of 5 V
Available in Space-Saving Small 2 mm × 2 mm 8Pin WSON Package
The input overcurrent threshold can be increased
using an external resistor. The device also offers
optional protection against reverse voltage at the
input using an external P-channel FET.
2 Applications
•
•
•
•
•
Mobile and Smart Phones
PDAs
MP3 Players
Low-Power Handheld Devices
Bluetooth™ Headsets
Device Information(1)
PART NUMBER
bq24308
PACKAGE
WSON (8)
BODY SIZE (NOM)
2.00 mm × 2.00 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Typical Application Circuit
5 CE
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.
bq24308
SLUS977B – SEPTEMBER 2009 – REVISED AUGUST 2015
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Table of Contents
1
2
3
4
5
6
7
8
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Device Comparison Table.....................................
Pin Configuration and Functions .........................
Specifications.........................................................
1
1
1
2
3
3
4
7.1
7.2
7.3
7.4
7.5
7.6
4
4
4
4
5
6
Absolute Maximum Ratings ......................................
ESD Ratings ............................................................
Recommended Operating Conditions.......................
Thermal Information .................................................
Electrical Characteristics...........................................
Typical Characteristics ..............................................
Detailed Description .............................................. 8
8.1 Overview ................................................................... 8
8.2 Functional Block Diagram ......................................... 8
8.3 Feature Description................................................... 9
8.4 Device Functional Modes........................................ 10
9
Application and Implementation ........................ 12
9.1 Application Information............................................ 12
9.2 Typical Application ................................................. 12
10 Power Supply Recommendations ..................... 17
11 Layout................................................................... 17
11.1 Layout Guidelines ................................................. 17
11.2 Layout Example .................................................... 17
12 Device and Documentation Support ................. 18
12.1
12.2
12.3
12.4
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
18
18
18
18
13 Mechanical, Packaging, and Orderable
Information ........................................................... 18
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision A (November 2009) to Revision B
Page
•
Changed SON to WSON throughout the document .............................................................................................................. 1
•
Added ESD Ratings 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
•
Changed the location of the ESD information from the ABS MAX table to the news ESD Ratings table ............................ 4
•
Moved Figures 1 through 10 from Typical Characteristics to Application Curves section .................................................. 14
Changes from Original (September 2009) to Revision A
Page
•
Changed Units from V to A for Input and Output Current spec in Absolute Maximum Ratings table.................................... 4
•
Changed VO(REG) test condition, IOUT value from 50 mA to 250 mA ....................................................................................... 5
•
Added TJ = 0°C to 125°C to test conditions for IOCP spec. ..................................................................................................... 5
•
Changed QEXT device symbol in the Input Reverse-Polarity Protection schematic. ........................................................... 14
2
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5 Device Comparison Table
PART NUMBER
MARKING
MEDIUM
QUANTITY
PACKAGE
bq24308DSGR
DAS
Tape and Reel
3000
2.00 mm × 2.00 mm
WSON
bq24308DSGT
DAS
Tape and Reel
250
2.00 mm × 2.00 mm
WSON
6 Pin Configuration and Functions
DSG Package
8-Pin WSON With Exposed Thermal Pad
Top View
IN 1
8 OUT
VSS 2
7 ILIM
bq24308
6 VBAT
PGATE 3
5 CE
NC 4
Pin Functions
PIN
NAME
NO.
I/O
DESCRIPTION
CE
5
I
Chip enable input. Active low. When CE = High, the input FET is off. Internally pulled down.
ILIM
7
I
Input overcurrent threshold programming. An optional external resistor can be used to increase input
overcurrent threshold. Connect a resistor to VSS to increase the OCP threshold.
IN
1
I
Input power, connect to external DC supply. Connect external 0.1μF (minimum) ceramic capacitor to VSS.
NC
4
—
Do not connect to any external circuit. This pin may have internal connections used for test purposes.
OUT
8
O
Output terminal to the charging system. Connect external 1-μF capacitor (minimum) ceramic capacitor to
VSS.
PGATE
3
O
Gate drive for optional external P-FET
VBAT
6
I
Battery voltage sense input. Connect to pack positive terminal through a resistor.
VSS
2
—
Thermal Pad
Ground terminal
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 pin must be connected to ground at
all times.
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7 Specifications
7.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) (1)
Input voltage
Input current
Output current
MIN
MAX
IN, PGATE (with respect to VSS)
–0.3
30
OUT (with respect to VSS)
–0.3
12
ILIM, CE, VBAT (with respect to VSS)
–0.3
7
UNIT
V
IN
2
A
OUT
2
A
PGATE
5
mA
Junction temperature, TJ
–40
150
°C
Storage temperature, Tstg
–65
150
°C
(1)
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
7.2 ESD Ratings
VALUE
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001
UNIT
±2000
(2)
Electrostatic Charged-device model (CDM), per JEDEC specification JESD22-C101
discharge
Air Discharge
IN (IEC 61000-4-2) (3)
Contact
V(ESD)
(1)
(2)
(3)
(1)
±500
V
±15000
±8000
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.
With IN bypassed to the VSS with a 1-μF low-ESR ceramic capacitor
7.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
VIN
Input voltage range
IIN
Input current, IN pin
IOUT
Output current, OUT pin
RILIM
OCP programming resistor
TJ
Junction temperature
MIN
NOM MAX
3.3
26
UNIT
V
1.5
A
1.5
31
–40
A
kΩ
125
°C
7.4 Thermal Information
bq24308
THERMAL METRIC
(1)
DSG (WSON)
UNIT
8 PINS
RθJA
Junction-to-ambient thermal resistance
58.6
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
67.9
°C/W
RθJB
Junction-to-board thermal resistance
29.7
°C/W
ψJT
Junction-to-top characterization parameter
1.2
°C/W
ψJB
Junction-to-board characterization parameter
30.3
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
7.6
°C/W
(1)
4
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report, SPRA953.
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7.5 Electrical Characteristics
over junction temperature range –40°C ≤ TJ ≤ 125°C and recommended supply voltage (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
IN
VUVLO
Undervoltage lock-out, input
power detected threshold
CE= Low, VIN: 0 V → 3 V
2.5
2.7
2.8
V
VHYS-UVLO
Hysteresis on UVLO
CE= Low, VIN: 3 V → 0 V
200
260
300
mV
tDGL(PGOOD)
Deglitch time, input power
detected status
CE = Low. Time measured from VIN
0V → 4 V 1 µs rise-time, to output turning ON
IDD
Operating current
CE= Low, VIN = 5 V, no load on OUT pin
ISTDBY
Standby current
8
ms
410
500
μA
CE= High, VIN = 5 V
65
95
μA
CE = Low, VIN = 4 V, IOUT = 250 mA
45
75
mV
INPUT TO OUTPUT CHARACTERISTICS
VDO
Drop-out voltage IN to OUT
INPUT OVERVOLTAGE PROTECTION
VOVP
Input overvoltage protection
threshold
CE= Low, VIN: 4 V to 10 V
6.1
6.3
6.5
V
VHYS-OVP
Hysteresis on OVP
CE= Low, VIN: 10 V to 4 V
20
60
110
mV
tPD(OVP)
Input OVP propagation delay (1)
CE= Low, Time measured from VIN 4 V → 10 V,
1µs rising time, to output turning OFF
0.2
1
μs
tON(OVP)
Recovery time from input
overvoltage condition
CE = Low, Time measured from VIN
10 V → 4V, 1 µs fall-time, to output turning ON
8
ms
OUTPUT VOLTAGE REGULATION
VO(REG)
Output voltage
CE = Low, VIN= 6 V, IOUT = 250 mA
4.85
5
5.15
V
Internal input overcurrent
protection threshold
CE= Low, VIN = 5V, ILIM floating;
TJ = 0°C to 125°C
630
700
770
mA
Input overcurrent protection range
CE = Low, VIN = 5V; TJ = 0°C to 125°C
630
1500
mA
INPUT OVERCURRENT PROTECTION
IOCP
ΔIOCP
OCP threshold accuracy
KILIM
Current limit programming:
IOCP(program) = IOCP + KILIM ÷
RILIM
tBLANK(OCP)
Blanking time, input overcurrent
detected
tREC(OCP)
Recovery time from input
overcurrent condition
TJ = 0°C to 125°C
±10%
TJ = –40°C to 125°C
±13%
25000
AΩ
CE= Low
5
ms
CE = Low
64
ms
BATTERY OVERVOLTAGE PROTECTION
BVOVP
Battery overvoltage protection
threshold
CE = Low, VIN > 4.4 V, VVBAT: 4.2 V → 4.5 V
4.3
4.35
4.40
V
VHYS-BOVP
Hysteresis on BVOVP
CE= Low, VIN > 4.4 V, VVBAT: 4.5 V → 3.9 V
200
275
320
mV
IVBAT
Input bias current on VBAT pin
VVBAT = 4.4 V, TJ = 25°C
10
nA
tDGL(BOVP)
Deglitch time, battery overvoltage
detected
CE= Low, VIN > 4.4 V, time measured from VVBAT
4.2 V → 4.5 V, 1 µs rising time, to output turning
OFF
176
µs
THERMAL PROTECTION
TJ(OFF)
Thermal shutdown temperature
TJ(OFF-HYS)
Thermal shutdown hysteresis
140
150
20
°C
°C
P-FET GATE DRIVER
VGCLMP
(1)
Gate driver clamp voltage
VIN > 17 V
13
15
17
V
Not tested in production. Specified by design.
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Electrical Characteristics (continued)
over junction temperature range –40°C ≤ TJ ≤ 125°C and recommended supply voltage (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
LOGIC LEVELS ON CE
VIL
Low-level input voltage
0
VIH
High-level input voltage
1.4
IIL
Low-level input current
IIH
High-level input current
0.4
V
V
VCE = 1.8 V
1
μA
15
μA
7.6 Typical Characteristics
Test conditions (unless otherwise noted) for typical operating performance are: VIN = 5 V, CIN = 1 μF, COUT = 1 μF, RBAT =
100 kΩ, ROUT = 16 Ω, TA = 25°C (see Figure 12)
70
2.75
2.7
60
VIN Increasing
VIN = 5 V
50
VDO @ 250 mA - mV
VUVLO, VHYS-UVLO - V
2.65
2.6
2.55
2.5
40
30
20
VIN Decreasing
2.45
2.4
-50
10
-30
-10
10
30
50
70
Temperature - °C
90
110
0
-50
130
0
50
Temperature - °C
100
150
Figure 2. Dropout Voltage (IN to OUT) vs Free-Air
Temperature
Figure 1. Undervoltage Lockout vs Free-Air Temperature
5.07
6.34
6.32
VOVP VHYS-OVP - V
VO - Output Voltage - V
5.05
5.03
5.01
6.3
VIN Increasing
6.28
6.26
6.24
VIN Decreasing
4.99
6.22
4.97
-50
0
50
Temperature - °C
100
150
Figure 3. Regulation Voltage (OUT Pin) vs Free-Air
Temperature
6
6.2
-50
0
50
Temperature - °C
100
150
Figure 4. OVP Threshold vs Free-Air Temperature
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Typical Characteristics (continued)
Test conditions (unless otherwise noted) for typical operating performance are: VIN = 5 V, CIN = 1 μF, COUT = 1 μF, RBAT =
100 kΩ, ROUT = 16 Ω, TA = 25°C (see Figure 12)
695
4.4
690
4.35
BVOVP (VVBAT Increasing)
685
4.3
BVOVP - V
IOCP - mA
680
675
4.25
4.2
670
4.15
665
4.1
Bat-OVP Recovery (VVBAT Decreasing)
660
655
-50
0
50
Temperature - °C
100
4.05
-50
150
-30
-10
10
30
50
70
Temperature - °C
90
110
130
Figure 6. Battery OVP Thresholds vs Free-Air Temperature
Figure 5. OCP Threshold vs Free-Air Temperature
1200
2.5
CE = L
1000
2
IDD, ISTDBY - mA
IVBAT - nA
800
1.5
1
600
400
CE = H
200
0.5
0
0
-50
-200
0
50
Temperature - °C
100
0
150
5
10
15
20
25
30
35
VIN - V
Figure 8. Supply Current vs Input Voltage
Figure 7. Leakage Current (BAT pin) vs Free-Air
Temperature
18
16
14
VPGATE - V
12
10
8
6
4
2
0
0
5
10
15
20
25
30
35
VIN - V
Figure 9. PGATE Voltage vs Input Voltage
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8 Detailed Description
8.1 Overview
The bq24308 device is a highly integrated circuit designed to provide protection to Li-ion batteries from failures of
the charging circuit. The device continuously monitors the input voltage, the input current, and the battery
voltage. In case of an input overvoltage condition, the device immediately removes power from the charging
circuit by turning off an internal switch. In the case of an overcurrent condition, it limits the current to a safe value
for a blanking duration before turning the switch off. Additionally, the device also monitors its own die
temperature and switches off if it becomes too hot.
The input and overcurrent threshold is user-programmable. The device can be controlled by a processor using
the CE pin.
8.2 Functional Block Diagram
Q1
IN
Charge Pump,
Bandgap,
Bias Gen
OUT
V REF
VISNS
VREF
VREF
Current limiting loop
VO(REG)Loop
V REF
ILIM
OFF
OCP Comparator
VREF - Δ
tBLANK(OCP)
VI SNS
VIN
VVLIM
CONTROL
AND STATUS
OVP Comparator
tBLANK(OVP)
VIN
VREF
CE
tDGL(PGOOD)
UVLO
VBAT
PGATE
level shift
THERMAL
VREF
SHUTDOWN
tDGL(BOVP)
VIN
VGCLMP
VSS
8
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8.3 Feature Description
8.3.1 Input Overvoltage Protection
The bq24308 device integrates an input overvoltage protection feature to protect downstream devices from faulty
input sources. If the input voltage rises above VOVP, the internal FET Q1 is turned off, removing power from the
circuit. As shown in Figure 16 to Figure 17, the response is very rapid, with the FET turning off in less than a
microsecond. When the input voltage returns below VOVP – Vhys(OVP) (but is still above UVLO), the FET Q1 is
turned on again after a deglitch time of tON(OVP) to ensure that the input supply has stabilized. Figure 18 shows
the recovery from input OVP.
8.3.2 Input Overcurrent Protection
The device can supply load current up to IOCP continuously. If the load current tries to exceed this threshold, the
current limits IOCP for a maximum duration of tBLANK(OCP). If the load current returns to less than IOCP before
tBLANK(OCP) times out, the device continues to operate (see Figure 19). However, if the overcurrent situation
persists for tBLANK(OCP), the FET Q1 is turned off for a duration of tREC(OCP). The FET is then turned on again and
the current is monitored all over again (see Figure 20 and Figure 21).
To prevent the input voltage from spiking up due to the inductance of the input cable, Q1 is turned off slowly in
an overcurrent fault condition, resulting in a "soft-stop", as shown in Figure 22. The overcurrent threshold is
programmed to a level greater than IOCP by connecting a resistor RILIM from the ILIM pin to VSS. The
programmed overcurrent threshold is given by the following equation:
IOCP(program) = IOCP + KILIM ÷ RILIM.
(1)
8.3.3 Battery Overvoltage Protection
The battery overvoltage threshold BVOVP is internally set to 4.35 V. If the battery voltage exceeds the BVOVP
threshold for longer than tDGL(BOVP), the FET Q1 is turned off (see Figure 23). This switch-off is also a soft-stop.
The FET Q1 is turned ON (soft-start) once the battery voltage drops to BVOVP – VHYS-BOVP.
8.3.4 Thermal Protection
If the junction temperature of the device exceeds TJ(OFF), FET Q1 is turned off. The FET is turned back on when
the junction temperature falls below TJ(OFF) – TJ(OFF-HYS).
8.3.5 Enable Function
The device has an enable pin, which can be used to enable or disable the device. When the CE pin is driven
high, the internal FET is turned off. When the CE pin is low, the FET is turned on if other conditions are safe. The
CE pin has an internal pulldown resistor of 200 kΩ (typical) and can be left floating.
8.3.6 PGATE Output
The bq24308 contains an external PFET driver (PGATE) for reverse polarity protection. When used with an
external P-Channel MOSFET, in addition to OVP, OCP, and Battery-OVP, the device offers protection against
input reverse polarity up to –30 V. When an input source with correct polarity is connected, the device first turns
on due to current flow through the body-diode of the external FET. The PGATE pin then goes low, turning ON
the external FET. For input voltages larger than VGCLMP, the voltage on the PGATE pin is driven to VIN – VGCLMP.
This ensures that the gate to source voltage seen by the external FET does not exceed –VGCLMP.
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8.4 Device Functional Modes
8.4.1 OPERATION Mode
The bq24308 device continuously monitors the input voltage, the input current, and the battery voltage. As long
as the input voltage is less than VOVP, the output voltage tracks the input voltage (less the drop caused by
RDSON of Q1). During fault conditions, the internal FET is turned off and the output is isolated from the input
source.
8.4.2 POWER-DOWN Mode
The device remains in POWER-DOWN mode when the input voltage at the IN pin is below the undervoltage
lock-out threshold, VUVLO. The FET Q1 (see Functional Block Diagram) connected between IN and OUT pins is
off. See Figure 10.
8.4.3 POWER-ON RESET Mode
The device resets all internal timers when the input voltage at the IN pin exceeds the UVLO threshold. The gate
driver for the external P-FET is enabled. The device then waits for duration tDGL(PGOOD) for the input voltage to
stabilize. If, after tDGL(PGOOD), the input voltage and battery voltage are safe, FET Q1 is turned ON. The device
has a soft-start feature to control the inrush current. This soft-start minimizes voltage ringing at the input (the
ringing occurs because the parasitic inductance of the adapter cable and the input bypass capacitor form a
resonant circuit). Figure 14 shows the power-up behavior of the device. Because of the deglitch time at poweron, if the input voltage rises rapidly to beyond the OVP threshold, the device will not switch on at all, as shown in
Figure 15.
10
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Device Functional Modes (continued)
Any State
If VIN < VUVLO,
go to Power Down
Power Down
All IC functions OFF
VIN > VUVLO?
No
Yes
Reset
Timers reset
Q1 off
Turn on PGATE
No
CE = Low ?
Yes
VIN < VOVP ?
Turn off Q1
No
Yes
I < IOCP ?
Turn off Q1
No
Wait tREC(OCP)
Yes
VVBAT < BVOVP ?
Turn off Q1
No
Yes
TJ < TJ(OFF) ?
No
Turn off Q1
Yes
Turn on Q1
Figure 10. State Diagram
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9 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
9.1 Application Information
The bq24308 device protects against overvoltage, overcurrent, and battery overvoltage events that occur due to
faulty adapter or other input sources. If any of these faults occur, the bq24308 device isolates the downstream
devices from the input source.
9.2 Typical Application
The typical values for an application are VOVP = 6.3 V, IOCP = 700 mA, and BVOVP = 4.35 V.
AC Adapter
VDC
GND
CIN
1
IN
OUT 8
1 mF
COUT
1 mF
Charging
Circuit
bq24308
SYSTEM
ILIM
5
7
VSS
CE
VBAT 6
2
RILIM
Optional
Terminal numbers shown are for the 2 × 2 DSG package.
Figure 11. Typical Application Diagram
9.2.1 Design Requirements
For this design example, use the parameters listed in Table 1.
Table 1. Design Parameters
DESIGN PARAMETER
EXAMPLE VALUE
Supply Voltage
5V
INILIM
1A
9.2.2 Detailed Design Procedure
9.2.2.1 Selection of RBAT
It is strongly recommended that the battery not be tied directly to the VBAT pin of the device, as under some
failure modes of the device, the voltage at the IN pin may appear on the VBAT pin. This voltage can be as high
as 30 V, and applying 30 V to the battery in case of the failure of the device and can be hazardous. Connecting
the VBAT pin through RBAT prevents a large current from flowing into the battery in case of failure of the device.
In the interests of safety, RBAT should have a very high value. The problem with a large RBAT is that the voltage
drop across this resistor because of the VBAT bias current IVBAT causes an error in the BVOVP threshold. This
error is over and above the tolerance on the nominal 4.35-V BVOVP threshold.
12
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Choosing RBAT in the range from 100 KΩ to 470 kΩ is a good compromise. In the case of a device failure, with
RBAT equal to 100 kΩ, the maximum current flowing into the battery would be (30 V – 3 V) ÷ 100 kΩ = 270 μA,
which is low enough to be absorbed by the bias currents of the system components. RBAT equal to 100 kΩ would
result in a worst-case voltage drop of RBAT × IVBAT = 1 mV. This is negligible compared to the internal tolerance of
50 mV on the BVOVP threshold.
If the Bat-OVP function is not required, the VBAT pin should be connected to VSS.
9.2.2.2 Selection of RCE
The CE pin can be used to enable and disable the device. If host control is not required, the CE pin can be tied
to ground or left unconnected, permanently enabling the device.
In applications where external control is required, the CE pin can be controlled by a host processor. As in the
case of the VBAT pin (see previous discussion), the CE pin should be connected to the host GPIO pin through
as large a resistor as possible. The limitation on the resistor value is that the minimum VOH of the host GPIO pin
less the drop across the resistor should be greater than VIH of the bq24308 device's CE pin. The drop across the
resistor is given by RCE × IIH.
9.2.2.3 Selection of Input and Output Bypass Capacitors
The input capacitor CIN in Figure 12 and Figure 13 is for decoupling and serves an important purpose. Whenever
there is a step change downwards in the system load current, the inductance of the input cable causes the input
voltage to spike up. CIN prevents the input voltage from overshooting to dangerous levels. It is strongly
recommended that a ceramic capacitor of at least 1 μF be used at the input of the device. It should be located in
close proximity to the IN pin.
COUT in Figure 12 and Figure 13 is also important: If a very fast (< 1 µs rise-time) overvoltage transient occurs at
the input, the current that charges COUT causes the device’s current-limiting loop to kick in, reducing the gatedrive to FET Q1. This results in improved performance for input overvoltage protection. COUT should also be a
ceramic capacitor of at least 1 µF, located close to the OUT pin. COUT also serves as the input decoupling
capacitor for the charging circuit downstream of the protection device.
AC Adapter
VDC
GND
CIN
1
IN
OUT 8
1 mF
COUT
1 mF
Charging
Circuit
bq24308
ILIM
5
7
SYSTEM
VSS
CE
VBAT 6
2
RILIM
Optional
Figure 12. Overvoltage, Overcurrent, and Battery Overvoltage Protection
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QEXT
AC Adapter
VDC
GND
100 KΩ
CIN
1
IN
1 μF
OUT 8
COUT
1 μF
3 PGATE
bq24080
Charger IC
bq24308
SYSTEM
100 KΩ
VBAT 6
RBAT
7 ILIM
VSS
47 KΩ
RILIM
Optional
CE 5
RCE
2
Figure 13. OVP, OCP, BATOVP With Input Reverse-Polarity Protection
9.2.2.4 Selection of the PGATE External MOSFET
The PGATE output drives the gate of an external MOSFET to protect the device from reverse polarity input
voltages. The MOSFET must be sized to handle the expected current in the application. Additionally, the
impedance of the MOSFET is in series with the internal FET of the bq24308, so that the overall acceptable
system resistance must be taken into account. Ensure the MOSFET VDS maximum rating exceeds the worstcase expected reverse voltage in the application. The bq24308 withstands up to –30 V, so a 30 V rating on the
MOSFET is a good target. The maximum VGS of the MOSFET must be greater than –17 V to ensure operation
up to 30 V inputs.
9.2.3 Application Curves
VIN
VIN
VOUT
tDGL(PGOOD)
VOUT
IOUT
IOUT
VIN = 0 V to 12 V
VIN = 0 V to 6 V
Figure 14. Normal Power-On Showing Soft-Start
14
tR = 50 μs
tR = 20 μs
Figure 15. Power-On with Input Overvoltage
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8.8V
8.4V
VIN < VUVLO
VIN
IN
VIN < VOVP
VIN < VO(REG)
VIN
6.4V
5.92V
VOUT
VOUT
VOUT
tR = 3 μs
VIN = 5 V to 8 V
Figure 16. OVP Response for Input Step
Figure 17. OUT Pin Response to Slow Input Ramp
VIN
VVININ
tON(OVP)
VOUT
tREC(OCP)
IOUT
tBLANK(OCP)
VIN = 8 V to 5 V
tF = 100 μs
Figure 18. Recovery from Input OVP
Figure 19. OCP, Powering up with OUT Pin Shorted to VSS
ROUT = 16W
ROUT = 16W
VOUT
ROUT = 2.8W
V
VOUTOUT
ROUT = 2.8W
IOUT
IOUT limited to 700mA
IOUT limited to 700mA
IOUT
tBLANK(OCP)
ROUT Switches from 16 Ω to 2.8 Ω
ROUT Switches from 16 Ω to 2.8 Ω
Figure 20. OCP, Showing Current Limiting
Figure 21. OCP, Showing Current Limiting and OCP
Blanking
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VVOUT
OUT
VVBAT
tDGL(BOVP)
VOUT
IOUT
VVBAT Steps from 4.3 V to 4.5 V.
Figure 22. Zoom-in on Turnoff Region of Figure 21,
Showing Soft-Stop
16
Figure 23. Battery OVP, tDGL(BOVP) and Soft-Stop
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10 Power Supply Recommendations
The intention is for the bq24308 device to operate with 5-V adapters with a maximum current rating of 1.5 A. The
device operates from sources from 3 V to 5.7 V. Outside of this range, the output is disconnected due to either
UVLO or the OVP function.
11 Layout
11.1 Layout Guidelines
•
•
•
This device is a protection device, and is meant to protect down-stream circuitry from hazardous voltages.
Potentially, high voltages may be applied to this device. It must be ensured that the edge-to-edge clearances
of PCB traces satisfy the design rules for the high voltages. See Figure 24.
The device uses WSON packages with a thermal pad. For good thermal performance, the thermal pad must
be thermally coupled with the PCB ground plane (GND). This requires a copper pad directly under the device.
This copper pad must be connected to the ground plane with an array of thermal vias.
CIN and COUT should be located close to the device. Other components like RILIM (optional) and RBAT must
also be located close to the device.
11.2 Layout Example
GND
VOUT
GND
GND
BAT+
VBAT
VIN
To GATE of FET
Figure 24. Layout Example Recommendation
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12 Device and Documentation Support
12.1 Community Resources
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
12.2 Trademarks
E2E is a trademark of Texas Instruments.
Bluetooth is a trademark of Bluetooth SIG, Inc..
All other trademarks are the property of their respective owners.
12.3 Electrostatic Discharge Caution
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.
12.4 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
13 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
18
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PACKAGE OPTION ADDENDUM
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29-Apr-2022
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
BQ24308DSGR
ACTIVE
WSON
DSG
8
3000
RoHS & Green NIPDAU | NIPDAUAG
Level-2-260C-1 YEAR
0 to 125
DAS
BQ24308DSGT
ACTIVE
WSON
DSG
8
250
RoHS & Green NIPDAU | NIPDAUAG
Level-2-260C-1 YEAR
0 to 125
DAS
(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)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
