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bq24257: Not Recommended For New Designs
bq24257
bq24258
SLUSBG0C – FEBRUARY 2013 – REVISED OCTOBER 2014
2
bq24257, bq24258 2-A Single Input I C, Standalone Switch-Mode Li-Ion/LiFePO4 Battery
Charger with Integrated Current-Sense Resistor
1
1 Features
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
High-efficiency Switch-mode Charger with
Integrated Current Sense Resistor
BC1.2 D+, D– Detection with Dead Battery
Provision (DBP) Pin-to-Sync with External USBPHI
USB Charging Compliant
Selectable Input Current Limit of 100 mA,
150 mA, 500 mA, 900 mA. 1.5 A, and 2 A
Watchdog Timer with Disable Bit
Integrated 4.9-V, 50-mA LDO
Complete System Level Protection
– Input UVLO, Input Overvoltage Protection
(OVP), Battery OVP, Sleep Mode, VIN_DPM
– Input Current Limit
– Charge Current Limit
– Thermal Regulation and Thermal Shutdown
– Voltage Based, JEITA Compatible NTC
Monitoring Input
– Safety Timer
In Host Mode, Programmable VBATREG, ICHG, ILIM,
VIN_DPM, VOVP and safety timer in host mode (after
I2C™ Communication and Before Watchdog
Timer Times Out)
In Standalone Mode, Resistor Programmable
ICHG, ILIM, and VIN_DPM in Standalone Mode (before
I2C™ Communication and After Watchdog Timer
Times Out)
20-V Maximum Input Voltage Rating
10.5-V Maximum Operating Input Voltage
Low RDS(on) Integrated Sense Resistor for up to 2A Charging Rate
Open Drain Status Outputs
Synchronous Fixed-frequency PWM Controller
Operating at 3 MHz for Small Inductor Support
AnyBoot Robust Battery Detection Algorithm
Charge Time Optimizer for Improved Charge
Times at any Given Charge Current
3 Description
The bq2425x is a highly integrated single-cell Li-Ion
battery charger with integrated current sense resistor
targeted for space-limited, portable applications with
high capacity batteries. The single cell charger has a
single input that operates from either a USB port or
AC wall adapter for a versatile solution. BC1.2
compatible D+, D- detection allows for recognition of
CDP, DCP, SDP, and non-standard USB adapters.
The use of an accessory dead battery provision
(DBP) pin allows for the system to sync a dead
battery state in order to enable or disable the BC1.2
detection in the event of an external USB-PHI.
The bq24257 has two modes of operation: 1) I2C
mode, and 2) Standalone mode. In I2C mode, the
host can adjust the charge parameters and monitor
the status of the charger operation. In Standalone
mode, the external resistor sets the input current limit,
charge current limit, and the input DPM level. This
mode also serves as the default settings when a DCP
adapter is present. The bq24257 enters host mode
while the I2C registers are accessed and the
watchdog timer has not expired (if enabled).
Device Information(1)
PART NUMBER
PACKAGE
bq24257
bq24258
(Product Preview)
BODY SIZE (NOM)
QFN (24)
4.15 mm x 4.15 mm
YFF (30)
2.027 mm x 2.427 mm
QFN (24)
4.15 mm x 4.15 mm
YFF (30)
2.027 mm x 2.427 mm
(1) For all available packages, see the orderable addendum at
the end of the datasheet.
Simplified Schematic for bq24257
CPMID
1µF
PMID
IN
VBUS
DD+
GND
SW
LO
1.0PH
CIN
CBOOT
33 nF
2.2PF
VDPM
3 MHz
PWM
BOOT
PGND
D-
CSIN
1PF
D+
Rsns
LDO
BAT
1 PF
System Load
VGPIO
22PF
2 Applications
•
•
•
•
Mobile Phones, Smart Phones
MP3 Players
Handheld Devices
Portable Media Player
LDO
SCL
SCL
SDA
SDA
Host GPIO1
TS
TEMP
PACK+
+
STAT
PACK-
GPIO2
/CE
GPIO3
/PG
ILIM
ISET
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. UNLESS OTHERWISE NOTED, this document contains PRODUCTION
DATA.
bq24257
bq24258
bq24257: Not Recommended For New Designs
SLUSBG0C – FEBRUARY 2013 – REVISED OCTOBER 2014
www.ti.com
Table of Contents
1
2
3
4
5
6
7
8
9
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Description(cont.) ..................................................
Device and Documentation Support....................
1
1
1
2
2
2
9.6 Typical Characteristics ............................................ 11
10 Detailed Description ........................................... 14
10.1
10.2
10.3
10.4
10.5
Overview ...............................................................
Functional Block Diagram .....................................
Feature Description...............................................
Device Functional Modes......................................
Register Maps .......................................................
14
15
16
29
31
6.1 Trademarks ............................................................... 2
6.2 Electrostatic Discharge Caution ................................ 3
11 Application and Implementation........................ 37
Device Comparison Table..................................... 3
Pin Configuration and FunctionsYFF package
status from preview to final. ................................. 3
Specifications......................................................... 5
12 Power Supply Recommendations ..................... 41
13 Layout................................................................... 41
9.1
9.2
9.3
9.4
9.5
14 Mechanical, Packaging, and Orderable
Information ........................................................... 42
ABSOLUTE MAXIMUM RATINGS ..........................
Handling Ratings ......................................................
RECOMMENDED OPERATING CONDITIONS .......
Thermal Information .................................................
ELECTRICAL CHARACTERISTICS .........................
5
5
6
6
7
11.1 Application Information.......................................... 37
11.2 Typical Application ............................................... 38
13.1 Layout Guidelines ................................................. 41
13.2 Layout Example .................................................... 41
13.3 Device and Documentation Support ..................... 42
4 Revision History
Changes from Original (February 2013) to Revision A
•
Changed Changed from a Product Brief to full data sheet..................................................................................................... 1
Changes from Revision A (March 2013) to Revision B
•
Page
Page
Changed Changed the Product Preview data sheet .............................................................................................................. 1
Changes from Revision B (#IMPLIED) to Revision C
Page
•
Changed datasheet to meet superior datasheet standards. ................................................................................................. 2
•
Changed YFF package status from preview to final. ............................................................................................................ 3
5 Description(cont.)
The bq24258 has only one mode of operation which is the Standalone. In this mode, the external resistor sets
the input current limit, charge current limit, and the input DPM level. This mode also serves as the default
settings when a DCP adapter is present. The EN1, EN2, and EN3 pin are available in the bq24258 spin to
support USB 3.0 compliance.
The battery is charged in four phases: trickle charge, pre-charge, constant current and constant voltage. In all
charge phases, an internal control loop monitors the device junction temperature and reduces the charge current
if the internal temperature threshold is exceeded. Additionally, a voltage-based, JEITA compatible battery pack
thermistor monitoring input (TS) is included that monitors battery temperature for safe charging.
6 Device and Documentation Support
6.1 Trademarks
I2C is a trademark of NXP B.V. Corporation.
All other trademarks are the property of their respective owners.
2
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Copyright © 2013–2014, Texas Instruments Incorporated
Product Folder Links: bq24257 bq24258
bq24257
bq24258
bq24257: Not Recommended For New Designs
www.ti.com
SLUSBG0C – FEBRUARY 2013 – REVISED OCTOBER 2014
6.2 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.
7 Device Comparison Table
DEVICE
DEFAULT
OVP
D+/D– or
EN1, EN2, EN3
DEFAULT
VOREG
VLOWV
TS or
DBP
Termination (1)
CHEM
I2C
ADDRESS
DEFAULT
USB ILIM
bq24257
6.5 V
D+/D-
4.2 V
3V
TS
10%
Li / LiPo
Yes
0x6A
100mA
bq24258
(Product
Preview)
10.5 V
EN1, EN2, EN3
4.2 V
3V
TS
10%
LiFePO4
No
0x6A
N/A (2)
(1)
(2)
Default behavior unless changed via I2C.
Selectable via the EN1, EN2, EN3 pins.
8 Pin Configuration and Functions
B
C
CSIN
PGND
BAT
CSIN
SW
IN
SW
SW
PGND
IN
IN
PMID
PGND
5
IN
CSIN
4
BOOT
BAT
BAT
3
ILIM
2
VDPM
A
1
LDO
30-Pin DSBGA, 24-Pin QFN
YFF, RGE Package
(Top View)
24
23
22
21
20
19
/CE
1
18
SW
D+
2
17
SW
D-
3
16
PGND
AGND
4
15
PGND
SDA
5
14
CSIN
SCL
6
13
CSIN
bq24257
D
E
ISET
/PG
D-
/CE
D+
SCL
STAT
VDPM
PMID
BOOT
TS
ISET
BAT
BAT
PMID
IN
ILIM
12
BOOT
LDO
11
ILIM
PGND
10
/PG
SDA
9
VDPM
TS
24
23
22
21
20
19
STAT
F
8
LDO
7
bq24257 WCSP
A
B
C
1
2
3
4
5
BAT
CSIN
PGND
SW
IN
BAT
BAT
CSIN
CSIN
PGND
SW
PGND
SW
IN
IN
/CE
1
18
SW
NC
2
17
SW
EN3
3
16
PGND
AGND
4
15
PGND
EN1
5
14
CSIN
EN2
6
13
CSIN
PMID
E
/PG
EN2
STAT
VDPM
BOOT
F
TS
EN1
PGND
LDO
ILIM
7
8
9
10
11
12
BAT
/CE
BAT
PGND
TS
EN3
ISET
ISET
/PG
D
STAT
bq24258
bq24258 WCSP
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bq24257: Not Recommended For New Designs
SLUSBG0C – FEBRUARY 2013 – REVISED OCTOBER 2014
www.ti.com
Pin Functions
PIN NAME
bq24257
bq24257
YFF
IN
A5,B5,C5
PMID
4
bq24258
(Product
Preview)
bq24258
(Product
Preview)
I/O
DESCRIPTION
RGE
YFF
RGE
19
A5,B5,C5
19
I
Input power supply. IN is connected to the external DC supply (AC adapter or
USB port). Bypass IN to PGND with >2-μF ceramic capacitor
D5
20
D5
20
I
Connection between blocking FET and high-side FET. Connect a 1-μF capacitor
from PMID to PGND as close to the PMID and PGND pins as possible
SW
A4,B4,C4
17-18
A4,B4,C4
17-18
O
Inductor Connection. Connect to the switching side of the external inductor.
BOOT
E5
21
E5
21
I
High-Side MOSFET Gate-Driver Supply. Connect a 0.033-μF ceramic capacitor
(voltage rating > 15 V) from BOOT to SW to supply the gate drive for the highside MOSFETs.
PGND
A3,B3,C3,
F3
15-16
A3,B3,C3,
D3,F3
15-16
CSIN
A2,B2,C2
13-14
A2,B2,C2
13-14
I
System Voltage Sense and SMPS output filter connection. Connect CSIN to the
system output at the output bulk capacitors. Bypass CSIN locally with at least 1
μF.
BAT
A1,B1,C1
11-12
A1,B1,C1
11-12
I/O
Battery Connection. Connect to the positive terminal of the battery. Additionally,
bypass BAT with at least 20-μF capacitor to GND.
TS
F1
9
F1
9
I
Battery Pack NTC Monitor. Connect TS to the center tap of a resistor divider
from LDO to GND. The NTC is connected from TS to GND. The TS function
provides four thresholds for JEITA or PSE compatibility. See the NTC Monitor
section for more details on operation and selecting the resistor values.
VDPM
E4
23
E4
23
I
Input DPM Programming Input. Connect a resistor divider between IN and GND
with VDPM connected to the center tap to program the Input Voltage based
Dynamic Power Management threshold (VIN_DPM). The input current is
reduced to maintain the supply voltage at VIN_DPM. The reference for the
regulator is 1.2 V. Short pin to GND if external resistors are not desired—this
sets a default of 4.68 V for the input DPM threshold.
ISET
D1
10
D1
10
I
Charge Current Programming Input. Connect a resistor from ISET to GND to
program the fast charge current.
ILIM
F5
22
F5
22
I
Input Current Limit Programming Input. Connect a resistor from ILIM to GND to
program the input current limit for IN. The current limit is programmable from 0.5
A to 2 A. ILIM has no effect on the USB input. If an external resistor is not
desired, short to GND for a 2-A default setting.
CE
D4
1
D4
1
I
Charge Enable Active-Low Input. Connect CE to a high logic level to place the
battery charger in standby mode.
EN1
--
--
F2
5
I
EN2
--
--
E2
6
I
Input Current Limit Configuration Inputs. Use EN1, EN2, and EN3 to control the
maximum input current and enable USB compliance. See Table 1 for
programming details.
EN3
--
--
D2
3
I
PG
E1
8
E1
8
O
Power Good Open Drain Output. PG is pulled low when a valid supply is
connected to IN. A valid supply is between VBAT + VSLP and VOVP. If no
supply is connected or the supply is out of this range, PG is high impedance.
STAT
E3
7
E3
7
O
Status Output. STAT is an open-drain output that signals charging status and
fault interrupts. STAT pulls low during charging. STAT is high impedance when
charging is complete or the charger is disabled. When a fault occurs, a 256-μs
pulse is sent out as an interrupt for the host. STAT is enabled/disabled using the
EN_STAT bit in the control register. STAT indicates recharge cycles. Connect
STAT to a logic rail using an LED for visual indication or through a 10-kΩ
resistor to communicate with the host processor.
Power Ground terminal. Connect to the ground plane of the circuit. For QFN
only, connect to the thermal pad of the device.
NC
--
--
--
2
SCL
E2
6
--
--
Not connected
SDA
F2
5
D+
D3
2
--
--
I
D-
D2
3
--
--
I
LDO
F4
24
F4
24
O
AGND
--
4
--
4
I
I2C Interface Clock. Connect SCL to the logic rail through a 10-kΩ resistor.
I/O
I2C Interface Data. Connect SDA to the logic rail through a 10-kΩ resistor.
BC1.2 compatible D+/D- Based Adapter Detection. Detects DCP, SDP, and
CDP. Also complies with the unconnected dead battery provision clause. D+
and D- are connected to the D+ and D- outputs of the USB port at power up.
Also includes the detection of Apple™ and TomTom™ adapters where a 500mA input current limit is enabled.
LDO output. LDO is regulated to 4.9 V and drives up to 50 mA. Bypass LDO
with a 1-μF ceramic capacitor. LDO is enabled when VUVLO < VIN < 19 V.
Analog Ground for QFN only. Connect to the thermal pad and the ground plane
of the circuit.
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bq24258
bq24257: Not Recommended For New Designs
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SLUSBG0C – FEBRUARY 2013 – REVISED OCTOBER 2014
9 Specifications
9.1 ABSOLUTE MAXIMUM RATINGS (1)
over operating free-air temperature range (unless otherwise noted)
Pin voltage range (with respect
to PGND)
MIN
MAX
IN
–1.3
20
V
SW
–0.7
12
V
PMID, BOOT
–0.3
20
V
CSIN, BAT, EN1,EN2, EN3, LDO, SCL, SDA, STAT, D+, D–, CE, ISET,
ILIM, VDPM
–0.3
7
V
–0.3
BOOT relative to SW
Output current (continuous)
Output sink current
UNIT
5
V
IN
2
A
CSIN, BAT
4
A
STAT
5
mA
Operating free-air temperature range
–40
85
°C
Junction temperature, TJ
–40
125
°C
(1)
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.
9.2 Handling Ratings
Tstg
Storage temperature range
MIN
MAX
UNIT
–65
150
°C
Lead temperature (soldering, 10 s)
V(ESD)
(1)
(2)
Electrostatic discharge
300
Human body model (HBM), per ANSI/ESDA/JEDEC JS-001, all
pins (1)
Charged device model (CDM), per JEDEC specification
JESD22-C101, all pins (2)
2
500
kV
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.
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bq24257: Not Recommended For New Designs
SLUSBG0C – FEBRUARY 2013 – REVISED OCTOBER 2014
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9.3 RECOMMENDED OPERATING CONDITIONS
All voltages are with respect to PGND if not specified. Currents are positive into, negative out of the specified pin. Consult
Packaging Section of the data book for thermal limitations and considerations of packages.
VIN
MIN
MAX
IN voltage range
4.35
18
IN operating voltage range (bq24258)
4.35
10.5
IN operating voltage range (bq24257)
4.35
6.5
UNITS
(1)
V
IIN
Input current
2
A
ICHG
Current in charge mode, BAT
2
A
IDISCHG
Current in discharge mode, BAT
RISET
Charge current programming resistor range
RILIM
Input current limit programming resistor range
TJ
Operating junction temperature range, TJ
(1)
4
A
75
Ω
105
Ω
0
125
ºC
The inherent switching noise voltage spikes should not exceed the absolute maximum rating on either the BOOT or SW pins. A tight
layout minimizes switching noise.
9.4 Thermal Information
THERMAL METRIC
bq24257,
bq24258
bq24257,
bq24258
QFN
YFF
24 PINS
30 PINS
RθJA
Junction-to-ambient thermal resistance
32.9
76.5
RθJC(top)
Junction-to-case (top) thermal resistance
32.8
0.2
RθJB
Junction-to-board thermal resistance
10.6
44.0
ψJT
Junction-to-top characterization parameter
0.3
1.6
ψJB
Junction-to-board characterization parameter
10.7
43.4
RθJC(bot)
Junction-to-case (bottom) thermal resistance
2.3
n/a
6
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UNIT
°C/W
Copyright © 2013–2014, Texas Instruments Incorporated
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bq24257: Not Recommended For New Designs
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SLUSBG0C – FEBRUARY 2013 – REVISED OCTOBER 2014
9.5 ELECTRICAL CHARACTERISTICS
bq24257 App Circuit, VUVLO < VIN < VOVP AND VIN > VBAT+VSLP, TJ = 0°C – 125°C and TJ = 25°C for typical values (unless
otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
INPUT CURRENTS
VUVLO < VIN < VOVP and VIN > VBAT + VSLP,
PWM switching, CE enable
IIN
IBAT
Supply current from IN
13
mA
VUVLO < VIN < VOVP and VIN > VBAT + VSLP,
PWM switching, CE disable
Battery discharge current in high
impedance SYSOFF mode , (BAT,
SW,CSIN)
5
0°C< TJ < 85°C, High-Z Mode
170
225
μA
0°C< TJ < 85°C, VBAT = 4.2 V,
VIN = 0 V or 5V, High-Z Mode
16
22
μA
1
μA
mΩ
0°C< TJ < 85°C, VBAT = 4.2 V,
VIN = 0V, SYSOFF Mode
BATTERY CHARGER
RSNS
Internal battery charger MOSFET onresistance
I2C mode
VBATREG
Measured from BAT to CSIN, VBAT = 4.2V
(WCSP)
20
30
Measured from BAT to CSIN, VBAT = 4.2V
(QFN)
30
40
Operating in voltage regulation,
Programmable range
SA mode
TJ = 25°C
Voltage regulation accuracy
TJ = 0°C to 125°C
3.5
4.44
V
4.2
–0.5%
0.5%
–0.75%
0.75%
Fast charge current range
VLOWV ≤ VBAT < VBATREG
500
2000
Fast charge current accuracy
I2C mode
–7%
+7%
ICHG_LOW
Low charge current Setting
Set via I2C
297
330
363
mA
KISET
Programmable fast charge current
factor
232.5
250
267.5
AΩ
ICHG
ICHG =
mA
KISET
RISET
(0.5 A ≤ ICHG < 2 A)
VISET
Maximum ISET pin voltage (in
regulation)
RISET-SHORT
Short circuit resistance threshold
0.42
Battery voltage rising bq24257
VLOWV
Hysteresis for VLOWV
IPRECHG
Pre-charge current
(VBATUVLO < VBAT < VLOWV)
Ipre-charge is percentile of the external
fast charge settings.
Battery under voltage lockout
threshold
VBAT rising
VBAT_UVLO
40
55
75
2.9
3
3.1
Battery voltage falling
VBATSHRT
Battery voltage rising
Hysteresis for VBATSHRT
Battery voltage falling
IBATSHRT
Trickle charge current
(VBAT < VBATSHRT)
tDGL(BATSHRT)
Deglitch time for trickle charge tp precharge transition
Termination current threshold
ITERM
Termination current threshold
tolerance
tDGL(TERM)
Deglitch time for charge termination
10
12
2.37
2.5
2.63
1.9
Termination Current on SA only
Both rising and falling, 2-mV overdrive,
tRISE, tFALL = 100 ns
Recharge threshold voltage
Below VBATREG
Deglitch time
VBAT falling below VRCH, tFALL = 100 ns
V
200
mV
32
ms
2
35
2.1
V
mV
50
mA
256
us
10
%ICHG
–10%
VRCH
% ICHG
100
25
tDGL(RCH)
V
mV
8
Deglitch time for pre-charge to fast
charge transition
Battery short threshold
Ω
100
Battery UVLO hysteresis
tDGL(LOWV)
V
10%
64
70
115
ms
160
32
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mV
ms
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bq24257: Not Recommended For New Designs
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www.ti.com
ELECTRICAL CHARACTERISTICS (continued)
bq24257 App Circuit, VUVLO < VIN < VOVP AND VIN > VBAT+VSLP, TJ = 0°C – 125°C and TJ = 25°C for typical values (unless
otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
BATTERY CHARGER LiFePO4 (bq24258)
VREG-OVCHG
Over charge voltage regulation
3.76
3.8
3.84
V
VFLT-CHG
Float charge regulation
3.46
3.5
3.54
V
VOVCHG
Overcharge comparator for LiFePo
3.65
3.7
3.75
VBAT rising
VOVCHG-HYS
tDGL(OVCHG)
VBAT falling
Deglitch on the overcharge
comparator
V
300
mV
32
ms
BATTERY DETECTION
VBATREG_HI
Battery detection high regulation
voltage
Same as VBATREG
VBATREG
V
VBATREG_LO
Battery detection low regulation
voltage
360 mV offset from VBATREG
VBATREG
- 480mV
V
VBATDET_HI
Battery detection comparator
VBATREG = VBATREG_HI
VBATREG
- 120 mV
V
VBATDET_LO
Battery detection comparator
VBATREG = VBATREG_LO
VBATREG
+ 120 mV
V
IDETECT
Battery detection sink current)
Always on during battery detection
7.5
mA
tDETECT
Battery detection time
For both VBATREG_HI and VBATREG_LO
32
ms
Tsafe
Safety timer accuracy
–10%
10%
INPUT PROTECTION
IIN
Input current limiting
IIN_LIMIT = 100 mA
90
95
100
IIN_LIMIT = 150 mA
135
142.5
150
IIN_LIMIT = 500 mA
450
475
500
IIN_LIMIT = 900 mA
810
860
910
IIN_LIMIT = 1500 mA
1400
1475
1550
IIN_LIMIT = 2000 mA
1850
1950
2050
ILIM =
IIN_LIMIT = External
ILIM
Maximum input current limit
programmable range for IN input
KILIM
Maximum input current factor for IN
input
VILIM
Maximum ILIM pin voltage (in
regulation)
RILIM-SHORT
Short circuit resistance threshold
VREF_DPM
VDPM_SHRT
VUVLO
tDGL(SLP)
VOVP
8
240
55
270
2000
mA
300
AΩ
83
V
105
Ω
SA mode
4.2
10
V
I2C mode
4.2
4.76
V
2%
VIN_DPM threshold accuracy
Both I2C and SA mode
-2%
DPM regulation voltage
External resistor setting only
1.15
VIN_DPM short threshold
If VDPM is shorted to ground, VIN_DPM
threshold will use internal default value
IC active threshold voltage
VIN rising
IC active hysteresis
VIN falling from above VUVLO
Sleep-mode entry threshold, VSUPPLYVSLP
RILIM
0.42
VIN_DPM threshold range
VIN_DPM
KILIM
500
ILIM = 500 mA to 2 A
mA
1.2
1.25
0.3
3.15
3.35
V
V
3.5
175
V
mV
VIN falling
0
50
100
mV
Sleep-mode exit hysteresis
VIN rising
40
100
160
mV
Deglitch time for supply rising above
VSLP+VSLP_EXIT
Rising voltage, 2-mV over drive, tRISE =
100ns
Input supply OVP threshold voltage
(bq24258)
IN rising
IN_OVP
-200mV
IN_OVP
IN_OVP
+200mV
Input supply OVP threshold voltage
(bq24257)
IN rising
IN_OVP
-200mV
IN_OVP
IN_OVP
+200mV
VOVP hysteresis
IN falling from VOVP
100
6.8
VBAT
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32
ms
V
mV
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ELECTRICAL CHARACTERISTICS (continued)
bq24257 App Circuit, VUVLO < VIN < VOVP AND VIN > VBAT+VSLP, TJ = 0°C – 125°C and TJ = 25°C for typical values (unless
otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
Deglitch time for IN Rising above
VOVP
IN rising voltage, tRISE = 100ns
Battery OVP threshold voltage
VBAT threshold over VBATREG to turn off
charger during charge
VBATOVP hysteresis
Lower limit for VBAT falling from above
VBOVP
1
BOVP Deglitch
Battery entering/exiting BOVP
1
RON(BLK)
Internal blocking MOSFET onresistance
Measured from IN to PMID (WCSP and
QFN)
RON(HS)
Internal high-side MOSFET onresistance
RON(LS)
Internal low-side MOSFET onresistance
ICbC
Cycle-by-cycle current limit
fOSC
Oscillator frequency
DMAX
Maximum duty cycle
DMIN
Minimum duty cycle
tDGL(OVP)
VBOVP
tDGL(BOVP)
MAX
UNIT
32
102.5
105
ms
107.5 % VBATREG
ms
PWM CONVERTER
TSHTDWN
TREG
60
100
mΩ
Measured from PMID to SW (WCSP and
QFN)
100
150
mΩ
Measured from SW to PGND (WCSP and
QFN)
110
165
mΩ
2.6
3.2
3.8
A
2.7
3
3.3
MHz
95%
0%
Thermal trip
150
Thermal hysteresis
10
Thermal regulation threshold
Charge current begins to cut off
VLDO
LDO output voltage
VIN = 5.5V, ILDO = 0 to 50 mA
ILDO
Maximum LDO output current
VLDO
LDO dropout voltage (VIN – VLDO)
°C
125
LDO
4.65
4.95
5.25
V
50
VIN = 5 V, ILDO = 50 mA
mA
200
300
30
30.4
mV
BATTERY-PACK NTC MONITOR
VHOT
High temperature threshold
VTS falling
VHYS(HOT)
Hysteresis on high threshold
VTS
VWARM
Warm temperature threshold
VTS falling
VHYS(WARM)
Hysteresis on warm temperature
threshold
VTS rising
VCOOL
Cool temperature threshold
VTS rising
VHSY(COOL)
Hysteresis on cool temperature
threshold
VTS falling
VCOLD
Low temperature threshold
VTS rising
VHYS(COLD)
Hysteresis on low threshold
VTS falling
VTS_DIS
TS disable threshold
tDGL(TS)
Deglitch time on TS change
29.6
rising
1
37.9
38.3
38.7
%VLDO
1
56.5
56.5
56.9
%VLDO
1
59.6
60
60.4
1
70
%VLDO
73
%VLDO
%VLDO
32
ms
INPUTS (DBP, EN1, EN2, EN3, CE, SCL, SDA)
VIH
Input high threshold
VIL
Input low threshold
1
V
0.4
V
STATUS OUTPUTS (STAT, PG, CHG)
VOL
Low-level output saturation voltage
IO = 5 mA, sink current
IIH
High-level leakage current
Hi-Z and 5 V applies
0.4
V
1
uA
TIMERS
tSAFETY
tWATCH-DOG
45 min safety timer
2700
s
6 hr safety timer
21600
s
9 hr safety timer
32400
s
Watch dog timer
50
s
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ELECTRICAL CHARACTERISTICS (continued)
bq24257 App Circuit, VUVLO < VIN < VOVP AND VIN > VBAT+VSLP, TJ = 0°C – 125°C and TJ = 25°C for typical values (unless
otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
D+, D– DETECTION
IDP_SRC
D+ current source for DCD
DCD
7
13
µA
RDM_DWN
D– pull-down resistance for DCD
DCD
14.25
24.8
kΩ
VDP_LOW
D+ low comparator threshold for DCD
DCD
0.85
0.9
0.95
V
VDP_SRC
D+ source voltage for primary
detection
Primary Detection
0.5
0.6
0.7
V
IDP_SRC_PD
D+ source voltage output current for
primary detection
Primary Detection
200
IDM_SINK
D– sink current for primary detection
Primary Detection
50
100
150
µA
VDAT_REF
Primary detection threshold
Primary Detection
250
325
400
mV
VLGC
Primary detection threshold
Primary Detection
0.85
0.9
0.95
V
VDM_SRC
D– source voltage for Secondary
Detection
Secondary Detection
0.5
0.6
0.7
V
IDM_SRC_PD
D– source voltage output current for
secondary detection
Secondary Detection
200
IDP_SINK
D+ sink current for secondary
detection
Secondary Detection
50
100
150
µA
VDAT_REF
Secondary detection threshold
Secondary Detection
250
325
400
mV
VATT_LO
Apple/TomTom detection low
threshold
Apple, TomTom Detection
1.8
1.85
1.975
V
VATT_HI
Apple/TomTom detection high
threshold
Apple, TomTom Detection
3.2
3.5
4.05
V
CI
Input capacitance
ID_LKG
10
Leakage current into D+/D–
µA
µA
D– , switch open
4.5
D+, switch open
4.5
pF
pF
D–, switch open
-1
1
µA
D+, switch open
-1
1
µA
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9.6 Typical Characteristics
Figure 1. Battery Detection
Figure 2. Battery Removal
88
4.350
ICHG = 2 A
VIN = 5 V
VREG = 4.2 V
86
4.340
4.335
82
VSYS-REG (V)
Efficiency (%)
84
4.345
80
78
76
4.330
4.325
4.320
4.315
74
4.310
72
4.305
bq24257
70
4.300
2.9
3.1
3.3
3.5
3.7
3.9
4.1
VBAT (V)
4.3
0.0
1.0
1.5
2.0
2.5
ISYS (A)
Figure 3. Efficiency vs. Battery Voltage
C004
Figure 4. System Voltage Regulation vs. Load Current
100
100
95
95
90
90
85
85
Efficiency (%)
Efficiency (%)
0.5
C001
80
75
70
65
80
75
70
65
60
V
VIN ==55V
VIN
60
V
VIN ==55V
VIN
55
VIN ==77V
V
VIN
55
VIN ==77V
V
VIN
VIN ==10
V
VIN
10V
50
0
200
400
600
800 1000 1200 1400 1600 1800 2000
Output Current (mA)
VIN ==10
V
VIN
10V
50
0
200
400
Figure 5. Efficiency vs. Output Current
600
800 1000 1200 1400 1600 1800 2000
Output Current (mA)
C002
C003
Figure 6. Efficiency vs. Output Current
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Typical Characteristics (continued)
20
16
18
14
16
Input Current (mA)
18
IBAT ( A)
12
10
8
6
4
CE EN
CE DIS
14
12
10
8
6
2
4
0
2
0
±2
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
VBAT (V)
5.0
0
5
10
15
20
Input Voltage (V)
C007
25
C008
Figure 8. Input IQ with Charge DIS and EN
Figure 7. VBAT IQ vs. IBAT
500
450
Input Current ( A)
400
350
300
250
200
ICHG = 1 A
ILIM = 1.5 A
ISYS = 0 A
VBAT = 3.6 V
150
100
50
0
0
5
10
15
20
Input Voltage (V)
25
C009
Figure 9. Input IQ with Charge Enable and Hz
Figure 10. Startup
ICHG = 1 A
ILIM = 1 A
VBAT = 3.9 V
VOVP = 10.5 V
ICHG = 2 A
ILIM = 0.5 A
ISYS = 0 A
VBAT = 3.6 V
VDPM = 4.36 V
Figure 11. Input OVP Event with INT
12
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Figure 12. VDPM Startup, 4.2 V
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Typical Characteristics (continued)
ICHG = 1 A
ISYS = 0 A
VBAT = 3.3 V
VIN = 5.2 V
Figure 13. 1.0-µH CCM Operation
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10 Detailed Description
10.1 Overview
The bq24257 is a highly-integrated, single-cell, Li-Ion battery charger with integrated current sense resistors
targeted for space-limited, portable applications with high-capacity batteries. The single-cell charger has a single
input that operates from either a USB port or AC wall adapter for a versatile solution.
The bq24257 device has two modes of operation:
1. I2C Mode
2. Standalone Mode
In I2C mode, the host adjusts the charge parameters and monitors the status of the charger operation. In
standalone mode, the external resistor sets the input-current limit, and charge current limit. Standalone mode
also serves as the default settings when a DCP adapter is present. It enters host mode while the I2C registers
are accessed and the watchdog timer has not expired (if enabled). The battery is charged in four phases: trickle
charge, pre-charge, constant current and constant voltage. In all charge phases, an internal control loop monitors
the device junction temperature and reduces the charge current if the internal temperature threshold is
exceeded.
14
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10.2 Functional Block Diagram
PMID
Q1
LDO
LDO
IN
Charge
Pump
Q2
VREF_CBCLIM
ILIM
_
+
BOOT
CbC
Comparator
IIN_LIM
Amp
_
VDPM
+
VREF_INLIM
VIN_DPM
Amp
+
VREF_DPM
PWM
LOOP SELECT
COMPENSATION
DRIVER
_
Host
SW
+
VDPM_DAC
_
V LDO
I2C Only
Q3
TJ
PGND
+
125C
ICHG
Amp
_
ISET
+
VBATREG
Amp
Sleep
Comparator
_
CSIN
_
+
VREF_BATREG
VREF_ICHG
VBAT +VSLP +
VREF_TERM
EN2 / D-
+
EN1 / D+
LDO
Termination
Comparator
Input
current limit
decoder /
D+ and DDecoder
Q4
Recharge Comparator
+
Batt Detect Or
Precharge
Curent Source
VBATREG ± 0.12V
VBAT
BAT
SCL
I2C
Controller
SDA
Charge
Pump
CHARGE
CONTROLLER
/ PG
-
BATSHORT Comparator
STAT
,
+
VBAT
VBATSHRT
Supplement Comparator
V SYS
+
DISABLE
VBAT
V BSUP
VLDO
+
/CE
TS -10°C
+
TS 0°C
+
TS 10 °C
+
TS 45 °C
+
TS 60°C
TS
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10.3 Feature Description
10.3.1 EN1, EN2, EN3 Pins
If the D+, D- detection pins are not used (bq24257), input current limit can be programmed through the host. The
EN1, EN2, and EN3 pins are available in the bq24258 spin to support USB 3.0 compliance. When the input
current limit pins change state, the VIN_DPM threshold changes as well. See Table 1 for details:
Table 1. EN1, and EN2 Truth Table (1)
(1)
16
EN3
EN2
EN1
INPUT CURRENT LIMIT
VINDPM THRESHOLD
0
0
0
500mA
4.36V
0
0
1
Externally programmed by ILIM (up to 2.0A)
Externally programmed VDPM
0
1
0
100mA
4.36V
0
1
1
Input Hi-Z
None
1
0
0
900mA
4.36V
1
0
1
Externally programmed by ILIM (up to 2.0 A)
Externally programmed VDPM
1
1
0
150mA
4.36V
1
1
1
Input Hi-Z
None
If EN3 = 0, it will be USB 2.0 compliant; If EN3 = 1, USB 3.0 compliant.
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10.3.2 I2C and Stand Alone Operation
The bq24257 series offers a unique feature when compared to traditional host mode chargers—the default input
current limit, output current limit and VIN_DPM parameters can be set via external resistors. In traditional host
mode chargers, the default parameters are programmed during manufacturing to set the I2C registers at a
specific default. If an end application calls for an alternate default setting, the traditional charger is left with the
only option of changing the parameters at the manufacturing stage. This may not always be acceptable.
Figure 14 illustrates the behavior of the bq24257 when transitioning between I2C mode and stand alone mode
(except for the bq24257).
Battery or Input
is Inserted
No
VIN or VBAT GOOD?
Yes
i2c command received?
No
ILIM=EN1/EN2
VDPM=External Default
ISET=External Default
Yes
ILIM=Register Value
VDPM=Register Value
ISET=Register Value
No
32s Watchdog Expired?
Yes
Figure 14. I2C and Stand Alone Mode Handoff
Once the battery or input is inserted and above the good thresholds, the device will determines if an I2C
command has been received in order to discern whether to operate from the I2C registers or the external
settings. Note that the bq24257 does not have EN1/EN2 pins and therefore the input current limit will be based
on the D+/D– results. When in host mode (I2C operation), the device will enter stand alone operation once the
watchdog timer expires.
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10.3.2.1 External Settings: ISET, ILIM and VIN_DPM
The fast charge current resistor (RISET) can be set by using the following formula:
K
250
RISET = ISET =
IFC
IFC
(1)
Where IFC is the desired fast charge current setting in Amperes.
The input current limit resistor (RILIM) can be set by using the following formula:
K
270
RILIM = ILIM =
IIC
IIC
(2)
Where IIC is the desired input current limit in Amperes.
Based on the application diagram reference designators, the resistor R1 and R2 can be calculated as follows to
set VIN_DPM:
R + R2
R + R2
VIN _ DPM = VREF _ DPM ´ 1
= 1.2 ´ 1
R2
R2
(3)
VIN_DPM should be chosen first along with R1. Choosing R1 first will ensure that R2 will be greater than the
resistance chosen. This is the case since VIN_DPM should be chosen to be greater than 2x VREF_DPM.
If resistors are not desired for BOM count reduction, the VDPM and the ILIM pins can be shorted to set the
internal defaults. However, the ISET resistor must be populated as this will be interpreted as a fault. Table 2
summarizes the settings when the ILIM, ISET, and VIN_DPM pins are shorted to GND.
Table 2. ILIM, VDPM, and ISET Short Behaviors
18
PIN SHORTED
BEHAVIOR
ILIM
Input current limit = 2 A
VDPM
VIN_DPM = 4.68 V
ISET
Fault—charging suspended
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10.3.3 BC1.2 D+/D– Detection
The bq24257 includes a fully BC1.2 compatible D+/D– source detection. This detection supports the following
types of ports:
• DCP (dedicated charge port)
• CDP (charging downstream port)
• SDP (standard downstream port)
• Apple™/TomTom™ ports
This D+/D– detection algorithm does not support ACA (accessory charge adapter) identification, but the input
current will default to 500mA when a charge port is attached to the ACA and bq24257 is connected to the OTG
port.
The D+/D– detection algorithm is only active when the device is in standalone mode (e.g. the host is not
communicating with the device and the watch dog timer has expired). However, when the device is in host mode
(that is, host is communicating via I2C to the device) writing a ‘1’ to register 0x04 bit location 4 (DPDM_EN)
forces the device to perform a D+/D– detection on the next power port insertion. This allows the D+/D– detection
to be enabled in both host mode and default mode.
The D+/D– detection algorithm has 5 primary states. These states are termed the following:
1. Data Contact Detect
2. Primary Detection
3. Secondary Detection
4. Non-standard Adapter Detection (for Apple™ / TomTom™)
5. Detection Configuration
The DCD state determines if the device has properly connected to the D+/D– lines. If the device is not in host
mode and VBUS is inserted (or DPDM_EN is true) the device will enter the DCD state and enable the
appropriate algorithm. If the DCD timer expires, the device will enter the Non-standard Adapter Detection (for
Apple™ / TomTom™) state. Otherwise it will enter the Primary Detection state.
When entering the Primary Detection state, the appropriate algorithm is enabled to determine whether to enter
the secondary detection state for DCP and CDP or the secondary detection state for SDP/Non-Standard
adaptors.
The non-standard adapter detection state for Apple™ / TomTom™ tests for the unique conditions for these nonstandard adapters. If the algorithm passes the unique conditions found with these adapters, it will proceed to the
Detection Configuration state. Otherwise it will revert back to the primary detection state.
The secondary detection state determines whether the input port is a DCP, CDP, SDP, or other non-standard
adapters. If the Primary Detection state indicated that the input port is either a DCP or CDP, the device will
enable the appropriate algorithm to differentiate between the two. If the Primary Detection state indicated that the
input port is either a SDP or non-standard adapter, the device will enable the appropriate algorithm to
differentiate between these two ports. Once complete, the device will continue to the Detection Configuration
state.
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DCP
Settings
www.ti.com
No
VBAT > VBATGD?
Yes
Turn on V DP_SRC
And keep it on until
CLR_VDP is set to ‘1’ in i2c
DCP
External ILIM
Start 6 hr timer
Non
Standard
Adapter
SDP
Settings
CDP
Settings
VBAT > VBATGD
Yes
No
Turn on VDP_SRC
And keep it on until
CLR_VDP is set to ‘1’
CDP and
weak battery
CDP and
good battery
SDP and
weak battery
SDP and
good battery
Apple/TT or
Non-Standard
IILIM=100mA
Start 45 min timer
IILIM=1500mA
Start 6 hr timer
IILIM=100mA
Start 45 min timer
Hi-Z mode
IILIM=0.5A
Start 6 hr timer
Detection Done.
Set detection
status in register
Figure 15. Detection Configuration State
The detection configuration state sets the input current limit of the device along with the charge timer. The
exception to the CDP and the SDP settings are due to the Dead Battery Provision (DBP) clause for unconnected
devices. This clause states that the device can pull a maximum of 100mA when not connected due to a dead
battery. During the battery wakeup time, the device sources a voltage on the D+ pin in order to comply with the
DBP clause. Once the battery is good, the system can clear the D+ pin voltage by writing a ‘1’ to address 0x07
bit position 4 (CLR_VDP). The device must connect to the host within 1sec of clearing the D+ pin voltage per the
DPB clause.
A summary of the input current limits and timer configurations for each charge port type are found in Table 3.
Table 3. D+, D– Detection Results per Charge Port Type
20
CHARGE PORT TYPE
INPUT CURRENT LIMIT
CHARGE TIMER
DCP
External ILIM
6 hours
45 minutes
CDP Dead Battery
100 mA
CDP Good Battery
1500 mA
6 hours
SDP Dead Battery
100 mA
45 minutes
SDP Good Battery
Hi-Z
N/A
Non-Standard
500 mA
6 hours
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10.3.4 Transient Response
The bq2425x includes an advanced hybrid switch mode control architecture. When the device is regulating the
charge current (fast-charge), a traditional voltage mode control loop is used with a Type-3 compensation
network. However, the bq2425x switches to a current mode control loop when the device enters voltage
regulation. Voltage regulation occurs in two charging conditions: 1) Battery voltage regulation (IBAT < ICHG), and 2)
Charge Done. This architecture allows for superior transient performance when regulating the voltage due to the
simplification of the compensation when using current mode control. The below transient response plot illustrates
a 0 A to 2-A load step with 4.7 ms full cycle and 12% duty cycle. A 3.9 V Li-Ion battery is used. The input voltage
is set to 5 V, charge current is set to 0.5 A and the input current is limited to 0.5 A. . Note that a high line
impedance input supply was used to indicate a realistic input scenario (adapter and cable). This is illustrated by
the change in VIN seen at the input of the IC.
The figure shows a ringing at both the input voltage and the input current. This is caused by the input current
limit speed up comparator.
Figure 16. 2A Load step Transient
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10.3.5
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AnyBoot Battery Detection
The bq24257 includes a sophisticated battery detection algorithm used to provide the system with the proper
status of the battery connection. The AnyBoot battery algorithm also guarantees the detection of voltage based
battery protectors that may have a long closure time (due to the hysteresis of the protection switch and the cell
capacity). The AnyBoot battery detection algorithm is utilizes a dual-voltage based detection methodology where
the csin rail will switch between two primary voltage levels. The period of the voltage level shift is 64ms and
therefore the power supply rejection of the down-system electronics will see this shift as essentially DC.
The AnyBoot algorithm has essentially 3 states. The 1st state is used to determine if the device has terminated
with a battery attached. If it has terminated due to the battery not being present, then the algorithm moves to the
2nd and 3rd states. The 2nd and 3rd states shift the csin voltage level between 4.2V and 3.72V. In each state there
are comparator checks to determine if a battery has been inserted. The two states guarantees the detection of a
battery even if the voltage of the cell is at the same level of the comparator thresholds. The algorithm will remain
in states 2 and 3 until a battery has been inserted. The flow diagram details for the Anyboot algorithm are shown
in Figure 17.
22
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Enter Battery
Detection
BATREG = Vreg
setting – 480mV
No
VBAT >
BATREG+120mV?
Yes
Yes
Battery Detected, STAT
register updated, and PTM
mode aborted (if enabled)
Yes
Battery Detected, STAT
register updated and
Exit Battery Detection
Yes
Battery Detected, STAT
register updated and
Exit Battery Detection
32ms Timer Expired?
No
No
25ms Timer Expired?
Yes
BATREG = 4.2V
No
VBAT < 4.08V?
Yes
32ms Timer Expired?
No
No
25ms Timer Expired?
Yes
ONLY ON FIRST LOOP ITERATION
“No Battery” Condition
BATREG = 4.2V
Update STAT Registers and send Fault Pulse
Yes
EN_PTM=1 and
NVM_EN_PTM=1?
Enter PTM mode
Exit Battery Detection
No
BATREG = 3.72V
No
VBAT > 3.84V?
Yes
32ms Timer Expired?
No
No
25ms Timer Expired?
Yes
Figure 17. AnyBoot Battery Detection Flow Diagram
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10.3.5.1 Input Voltage Based DPM
During normal charging process, if the input power source is not able to support the programmed or default
charging current, the supply voltage deceases. Once the supply drops to VIN_DPM, the input current limit is
reduced down to prevent the further drop of the supply. When the IC enters this mode, the charge current is
lower than the set. This feature ensures IC compatibility with adapters with different current capabilities without a
hardware change.
10.3.5.2 Sleep Mode
The bq2425x enters the low-power sleep mode if the voltage on VIN falls below sleep-mode entry threshold,
VBAT + VSLP, and VIN is higher than the under-voltage lockout threshold, VUVLO. This feature prevents draining the
battery during the absence of VIN. When VIN < VBAT + VSLP, the bq2425x turns off the PWM converter, turns on
the battery FET, sends a single 256 μs pulse is sent on the STAT output and the FAULT/STAT bits of the status
registers are updated in the I2C. Once VIN > VBAT + VSLP with the hysteresis, the FAULT bits are cleared and the
device initiates a new charge cycle.
10.3.5.3 Hiz Mode
Set the HZ_MODE bit to 1 to put the device in Hiz mode. In Hiz, the charger device is in low-power standby
mode and the switch mode controller is disabled.
10.3.5.4 Input Over-Voltage Protection
The bq2425x provides over-voltage protection on the input that protects downstream circuitry. The built-in input
over-voltage protection to protect the device and other components against damage from over voltage on the
input supply (Voltage from VIN to PGND). When VIN > VOVP, the bq2425x turns off the PWM converter, turns the
battery FET, sends a single 256 μs pulse is sent on the STAT output and the FAULT/STAT bits of the status
registers and the battery/supply status registers are updated in the I2C. Once the OVP fault is removed, the
FAULT bits are cleared and the device returns to normal operation. The OVP threshold for the bq2425x is
programmable from 6.5 V to 10.5 V using VOVP bits in register #7.
24
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10.3.5.5 NTC Monitor (contact the local TI representative for function availability)
The bq24257 includes the integration of an NTC monitor pin that complies with the JEITA specification (PSE also
available upon request). The voltage based NTC monitor allows for the use of any NTC resistor with the use of
the circuit shown below:
LDO
R2
TS
NTC
R3
Figure 18. Voltage Based NTC Circuit
The use of R3 is only necessary when the NTC does not have a beta near 3500K. When deviating from this
beta, error will be introduced in the actual temperature trip thresholds. The trip thresholds are summarized below
which are typical values provided in the specification table.
Table 4. Ratiometric TS Trip Thresholds for JEITA Compliant Charging
VHOT
30.0%
VWARM
38.3%
VCOOL
56.5%
VCOLD
60%
When sizing for R2 and R3, it is best to solve two simultaneous equations that ensure the temperature profile of
the NTC network will cross the VHOT and VCOLD thresholds. The accuracy of the VWARM and VCOOL thresholds will
depend on the beta of the chosen NTC resistor. The two simultaneous equations are shown below:
%VCOLD
æ R3 RNTC
ö
TCOLD ÷
ç
ç R3 + RNTC
÷
TCOLD ø
= è
´ 100
æ R3 RNTC
ö
TCOLD
ç
÷ + R2
ç R3 + RNTC
÷
TCOLD
è
ø
%VHOT
æ R3 RNTC
ö
THOT ÷
ç
ç R3 + RNTC
÷
THOT ø
= è
´ 100
æ R3 RNTC
ö
THOT
ç
÷ + R2
ç R3 + RNTC
÷
THOT
è
ø
(4)
Where the NTC resistance at the VHOT and VCOLD temperatures must be resolved as follows:
b 1
-1
TCOLD To
RNTC
TCOLD
RNTC
THOT
= Ro e
(
β 1
-1
THOT To
=Ro e
(
)
)
(5)
To be JEITA compliant, TCOLD must be 0°C and THOT must be 60°C. If an NTC resistor is chosen such that the
beta is 4000K and the nominal resistance is 10kΩ, the following R2 and R3 values result from the above
equations:
R2 = 5 kΩ
R3 = 9.82 kΩ
Figure 19 illustrates the temperature profile of the NTC network with R2 and R3 set to the above values.
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Example NTC Network Profile of %LDO vs. TEMP
60
Tcool
LDO Percent (%)
55
50
45
40
Twarm
35
30
0
10
20
30
40
50
60
Temperature (C)
Figure 19. Voltage Based NTC Circuit Temperature Profile
For JEITA compliance, the TCOOL and TWARM levels are to be 10°C and 45°C respectively. However, there is
some error due to the variation in beta from 3500K. As shown above, the actual temperature points at which the
NTC network crosses the VCOOL and VWARM are 13°C and 47°C respectively. This error is small but should be
considered when choosing the final NTC resistor.
Once the resistors are configured, the internal JEITA algorithm will apply the below profile at each trip point for
battery voltage regulation and charge current regulation.
Charge
Programmed VBAT_REG
4.10 V max
4.06 V typ
No Charge
No Charge
Programmed ICHG (1C)
Charge
0.5C
No Charge
No Charge
TS_DIS
VCOLD
VCOOL
VWARM
VHOT
Figure 20. JEITA Profile for Voltage and Current Regulation Loops
26
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10.3.6 Production Test Mode
To aid in end mobile device product manufacturing, the bq24257 includes a Production Test Mode (PTM), where
the device is essentially a DC-DC buck converter. In this mode the input current limit to the charger is disabled
and the output current limit is limited only by the inductor cycle-by-cycle current (e.g. 3.5A). The PTM mode can
be used to test systems with high transient loads such as GSM transmission without the need of a battery being
present.
As a means of safety, the Anyboot algorithm will determine if a battery is not present at the output prior to
enabling the PTM mode. If a battery is present and the software attempts to enter PTM mode, the device will not
enable PTM mode.
10.3.7 Safety Timer
At the beginning of charging process, the bq24257 starts the safety timer. This timer is active during the entire
charging process. If charging has not terminated before the safety timer expires, the IC enters suspend mode
where charging is disabled. The safety timer time is selectable using the I2C interface. A single 256μs pulse is
sent on the STAT output and the FAULT/ bits of the status registers are updated in the I2C.
This function prevents continuous charging of a defective battery if the host fails to reset the safety timer. The
safety timer runs at 2x the normal rate under the following conditions: Pre-charge mode, during thermal
regulation where the charge current is reduced, during TS fault where the charge current reduced due to
temperature rise on the battery, input current limit. The safety timer is suspended during OVP, TS fault where
charge is disabled, thermal shut down, and sleep mode.
10.3.8 Fault Modes
The bq2425x family includes several hardware fault detections. This allows for specific conditions that could
cause a safety concern to be detected. With this feature, the host can be alleviated from monitoring unsafe
charging conditions and also allows for a “fail-safe” if the host is not present. Table 5 summarizes the faults that
are detected and the resulting behavior.
Table 5. Fault Condition
Fault Condition
Charger Behavior
Safety Timer Behavior
Suspended
Input OVP
ICHG Disabled
Input UVLO
ICHG Disabled
Reset
Sleep (VIN < VBAT)
ICHG Disabled
Suspended
TS Fault (Batter Over Temp)
ICHG Disabled
Suspended
Thermal Shutdown
ICHG Disabled
Suspended
Timer Fault
ICHG Disabled
Reset
No Battery
ICHG Disabled
Suspended
ISET Short
ICHG Disabled
Suspended
Input Fault and LDO Low
ICHG Disabled
Suspended
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10.3.9 Watchdog Timer
In addition to the safety timer, the bq24257 contains a 50-second watchdog timer that monitors the host through
the I2C interface. Once a write is performed on the I2C interface, a watchdog timer is reset and started. The
watchdog timer can be disabled by writing “0” on WD_EN bit of register #1. Writing “1” on that bit enables it and
reset the timer.
If the watchdog timer expires, the IC enters DEFAULT mode where the default charge parameters are loaded
and charging continues. The I2C may be accessed again to re-initialize the desired values and restart the
watchdog timer as long as the safety timer has not expired. Once the safety timer expires, charging is disabled.
10.3.10 Thermal Regulation and Thermal Shutdown
During the charging process, to prevent overheat of the chip, bq2425x monitors the junction temperature, TJ, of
the die and begins to taper down the charge current once TJ reaches the thermal regulation threshold, TREG.
The charge current is reduced when the junction temperature increases about above TREG. Once the charge
current is reduced, the system current is reduced while the battery supplements the load to supply the system.
This may cause a thermal shutdown of the IC if the die temperature rises too. At any state, if TJ exceeds
TSHTDWN, bq2425x suspends charging and disables the buck converter. During thermal shutdown mode, PWM is
turned off, all timers are suspended, and a single 256 μs pulse is sent on the STAT output and the FAULT/STAT
bits of the status registers are updated in the I2C. A new charging cycle begins when TJ falls below TSHTDWN
by approximately 10°C.
28
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10.4 Device Functional Modes
The bq24257 family provides a switch-mode buck regulator with output non-power path and a charge controller
to provide optimum performance over the full battery charge cycle. The control loop for the buck regulator has 6
primary feedback loops that can set the duty cycle:
1. Constant Current (CC)
2. Constant Voltage (CV)
3. Input Current (IILIM)
4. Input Voltage (VIN_DPM)
5. Die Temperature
6. Cycle by Cycle Current
The feedback with the minimum duty cycle is chosen as the active loop. The bq24257 supports a precision Li-Ion
or Li-Polymer charging system for single-cell applications. The bq24257 includes an integrated charge sense
resistor for highly accurate charge current sensing while reducing the external BOM requirements. Figure 21
below illustrates a typical charge profile.
Trickle
Charge
Precharge
Current Regulation
Phase (CC)
Voltage Regulation
Phase (CV)
Termination
VBATREG
ICHG
ICHG
VCSIN
VBAT
VLOWV
VBATSHRT
IPRECHG
ITERM
IBATSHRT
Charging on
Charge done
Figure 21. Li-ion Battery Charge Profile
The bq24258 supports an advanced Lithium-Iron-Phosphate (LiFePO4) algorithm. This allows for the charger to
source the charge current up to the VREG-OVCHG level before entering the float charge region. See Figure 22
below for the charge profile characteristics:
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Device Functional Modes (continued)
Trickle
Charge
Precharge
VBATREG
(3.8V)
VOVRCHG
(3.7V)
VFLTCHG
(3.5V)
Current Regulation
Phase (CC)
Discharge
Float Charge
ICHG
ICHG
VCSIN
VBAT
VLOWV
VBATSHRT
IPRECHG
IBATSHRT
Figure 22. LiFePO4 Battery Charge Profile
30
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10.5 Register Maps
Register #1
Memory location: 00, Reset state: x0xx xxxx
BIT
•
•
•
•
NAME
Read/Write
FUNCTION
B7(MSB)
WD_FAULT
Read only
Read: 0 – No fault
1 – WD timeout if WD enabled
B6
WD_EN
Read/Write
0 – Disable
1 – Enable (also resets WC timer)
B5
STAT_1
Read only
B4
STAT_0
Read only
B3
FAULT_3
Read only
B2
FAULT_2
Read only
B1
FAULT_1
Read only
B0(LSB)
FAULT_0
Read only
00 –
01 –
10 –
11 –
Ready
Charge in progress
Charge done
Fault
0000 –
0001 –
0010 –
0011 –
0100 –
0101 –
0110 –
0111 –
1000 –
1001 –
1010 –
Normal
Input OVP
Input UVLO
Sleep
Battery Temperature (TS) Fault
Battery OVP
Thermal Shutdown
Timer Fault
No Battery connected
ISET short
Input Fault & LDO Low
WD_FAULT – ‘0’ indicates no watch dog fault has occurred, where a ‘1’ indicates a fault has previously
occurred.
WD_EN – Enables or disables the internal watch dog timer. A ‘1’ enables the watch dog timer and a ‘0’
disables it.
STAT – Indicates the charge controller status
FAULT – Indicates the faults that have occurred. If multiple faults occurred, they can be read by sequentially
addressing this register (e.g. reading the register 2 or more times). Once all faults have been read and the
device is in a non-fault state, the fault register will show “Normal”. Regarding the "Input Fault & LDO Low" ,
the IC will indicates this fault if the LDO is low and at the same time the input is below UVLO or coming out of
UVLO with LDO still low.
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Register #2
Memory location: 01, Reset state: 1010 1100
BIT
•
•
•
•
•
32
NAME
Read/Write
FUNCTION
Write:
1 – Reset all registers to default values
0 – No effect
B7(MSB)
Reset
Write only
B6
IIN_ILIMIT_2
Read/Write
B5
IIN_ILIMIT_1
Read/Write
B4
IIN_ILIMIT
_0
Read/Write
B3
EN_STAT
Read/Write
0 – Disable STAT function
1 – Enable STAT function
B2
EN_TERM
Read/Write
0 – Disable charge termination
1 – Enable charge termination
B1
CE
Read/Write
0 – Charging is enabled
1 – Charging is disabled
B0(LSB)
HZ_MODE
Read/Write
0 – Not high impedance mode
1 – High impedance mode
000 – USB2.0 host with 100mA current limit
001 – USB3.0 host with 150mA current limit
010 – USB2.0 host with 500mA current limit
011 – USB3.0 host with 900mA current limit
100 – Charger with 1500mA current limit
101 – Charger with 2000mA current limit
110 – External ILIM current limit(5)
111- No input current limit with internal clamp at 3A (PTM MODE)
IIN_LIMIT – Sets the input current limit level. When in host mode this register sets the regulation level. However,
when in standalone mode (e.g. no I2C writes have occurred after power up or the WD timer has expired) the
external resistor setting for IILIM sets the regulation level.
EN_STAT – Enables and disables the STAT pin. When set to a ‘1’ the STAT pin is enabled and function
normally. When set to a ‘0’ the STAT pin is disabled and the open drain FET is in HiZ mode.
EN_TERM – Enables and disables the termination function in the charge controller. When set to a ‘1’ the
termination function will be enabled. When set to a ‘0’ the termination function will be disabled. When
termination is disabled, there are no indications of the charger terminating (i.e. STAT pin or STAT registers).
CE – The charge enable bit which enables or disables the charge function. When set to a ‘0’, the charger
operates normally. When set to a ‘1’, the charger is disabled.
HZ_MODE – Sets the charger IC into low power standby mode. When set to a ‘1’, the switch mode controller
is disabled. When set to a ‘0’, the charger operates normally.
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Register #3
Memory location: 02, Reset state: 1000 1111
BIT
NAME
Read/Write
FUNCTION
B7(MSB)
VBATREG_5
(1)
Read/Write
Battery Regulation Voltage: 640mV (default 1)
B6
VBATREG_4
(1)
Read/Write
Battery Regulation Voltage: 320mV (default 0)
B5
VBATREG_3
(1)
Read/Write
Battery Regulation Voltage: 160mV (default 0)
B4
VBATREG_2
(1)
Read/Write
Battery Regulation Voltage: 80mV (default 0)
B3
VBATREG_1
(1)
Read/Write
Battery Regulation Voltage: 40mV (default 1)
B2
VBATREG_0
(1)
Read/Write
Battery Regulation Voltage: 20mV (default 1)
USB_DET_1/EN1
Read Only
USB_DET_0/EN0
Read Only
Return USB detection result or pin EN1/EN0 status –
00 – DCP detected / EN1=0, EN0=0
01 – CDP detected / EN1=0, EN0=1
10 – SDP detected / EN1=1, EN0=0
11 – Apple/TT or non-standard adaptor detected/EN1=1, EN0=1
(4)(5)
B1
B0(LSB)
(1)
•
•
Charge voltage range is 3.5V—4.44V with the offset of 3.5V and step of 20mV (default 4.2V)
VBATREG – Sets the battery regulation voltage
USB_DET/EN – Provides status of the D+/D– detection results for spins that include the D+/D– pins or the
state of EN1/EN2 for spins that include the EN1/EN2 pins.
Register #4
Memory location: 03, Reset state: 0000 0000
BIT
Read/Write
FUNCTION
B7(MSB)
ICHG_4
(1) (2)
Read/Write
Charge current 800mA – (default 0)
B6
ICHG_3
(1) (2)
Read/Write
Charge current: 400mA – (default 0)
B5
ICHG_2
(1) (2)
Read/Write
Charge current: 200mA – (default 0)
B4
ICHG_1
(1) (2)
Read/Write
Charge current: 100mA – (default 0)
B3
ICHG_0
(1) (2)
Read/Write
Charge current: 50mA – (default 0)
ITERM_2
(3)
Read/Write
Termination current sense threshold: 100mA (default 0)
B1
ITERM_1
(3)
Read/Write
Termination current sense threshold: 50mA (default 0)
B0(LSB)
ITERM_0
(3)
Read/Write
Termination current sense threshold: 25mA (default 0)
B2
(1)
(2)
(3)
•
•
NAME
Charge current offset is 500mA and default charge current is 500mA (maximum is 2.0A)
When all bits are 1’s, it is external ISET charging mode
Termination threshold voltage offset is 50mA. The default termination current is 50mA if ICHG is selected from I2C. Otherwise,
termination is set to 10% in external I_set mode with +/-10% accuracy.
ICHG – Sets the charge current regulation
ITERM – Sets the current level at which the charger will terminate
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Register #5
Memory location: 04, Reset state: xx00 x010
BIT
NAME
Read/Write
B7(MSB)
LOOP_STATUS1 (1)
Read Only
B6
LOOP_STATUS0 (1)
Read Only
B5
LOW_CHG
Read/Write
0 – Normal charge current set by 03h
1 – Low charge current setting 330mA (default 0)
B4
DPDM_EN
Read/Write
0 – Bit returns to 0 after D+/D– detection is performed
1 – Force D+/D– detection (default 0)
B3
CE_STATUS
Read Only
0 – CE low
1 – CE high
B2
VINDPM_2 (2)
Read/Write
Input VIN-DPM voltage: 320mV (default 0)
B1
(2)
Read/Write
Input VIN-DPM voltage: 160mV (default 1)
VINDPM_0 (2)
Read/Write
Input VIN-DPM voltage: 80mV (default 0)
B0(LSB)
(1)
(2)
•
•
•
•
34
VINDPM_1
FUNCTION
00 –
01 –
10 –
11 –
No loop is active that slows down timer
VIN_DPM regulation loop is active
Input current limit loop is active
Thermal regulation loop is active
LOOP_STATUS bits show if there are any loop is active that slow down the safety timer. If a status occurs, these bits announce the
status and do not clear until read. If more than one occurs, the first one is shown
VIN-DPM voltage offset is 4.20V and default VIN_DPM threshold is 4.36V.
LOOP_STATUS – Provides the status of the active regulation loop. The charge controller allows for only one
loop to regulate current at a time.
LOW_CHG – When set to a ‘1’, the charge current is reduced 330mA independent of the charge current
setting in register 0x03. When set to ‘0’, the charge current is set by register 0x03.
DPDM_EN – Forces a D+/D– detection routine to be executed once a ‘1’ is written. This is independent of the
input being supplied.
CE_STATUS – Provides the status of the CE pin level. If the CE pin is forced high, this bit returns a ‘1’. If the
CE pin is forced low, this bit returns a ‘0’.
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Register #6
Memory location: 05, Reset state: 101x 1xxx
•
•
•
•
BIT
NAME
Read/Write
B7(MSB)
2XTMR_EN
Read/Write
0 – Timer not slowed at any time
1 – Timer slowed by 2x when in thermal regulation, VIN_DPM or DPPM (default 1)
FUNCTION
B6
TMR_1
Read/Write
B5
TMR_2
Read/Write
Safety Timer Time Limit
00 – 0.75 hour fast charge
01 – 6 hour fast charge (Default 01)
10 – 9 hour fast charge
11 – Disable safety timers
B4
SYSOFF
Read/Write
0 – SYSOFF disabled
1 – SYSOFF enabled
B2
TS_STAT2
Read only
B1
TS_STAT1
Read only
B0(LSB)
TS_STAT0
Read only
TS Fault Mode:
000 – Normal, No TS fault
100 – TS temp < TCOLD (Charging suspended for JEITA and Standard TS)
101 – TFREEZE < TS temp < TCOLD (Charging at 3.9V and 100mA and only for PSE option
only)
110 – TS temp < TFREEZE (Charging suspended for PSE option only)
111 – TS open (TS disabled)
2xTMR_EN – When set to a ‘0’, the 2x Timer function is enabled and allows for the timer to be extended if a
condition occurs where the charge current is reduced (that is, VIN_DPM, thermal regulation, and so on). When
set to a ‘1’, this function is disabled and the normal timer will always be executed independent of the current
reduce conditions.
SYSOFF – When set to a ‘1’ and the input is removed, the leakage from the BAT pin will be changed to less
than 1µA. Note that this disconnects the battery from the IC. When set to a ‘0’, this function is disabled.
TS_EN – Enables and disables the TS function. When set to a ‘1’ the TS function is disabled otherwise it is
enabled. Only applies to spins that have a TS pin.
TS_STAT – Provides status of the TS pin state for spins that have a TS pin.
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Register #7
Memory location: 06, Reset state: 1110 0000 for the bq24258 and 0010 0000 for the bq24257.
BIT
NAME
Read/Write
B7(MSB)
VOVP_2
Read/Write
B6
VOVP_1
Read/Write
FUNCTION
OVP voltage:
000 – 6.0V; 001 – 6.5V; 010 – 7.0V; 011 – 8.0V
100 – 9.0V; 101 – 9.5V; 110 – 10.0V; 111 –10.5V
B5
VOVP_0
Read/Write
B4
CLR_VDP
Read/Write
0 – Keep D+ voltage source on during DBP charging
B3
FORCE_BATDET
Read/Write
0 – Enter the battery detection routine only if TERM is true or EN_PTM is true
B2
FORCE_PTM
Read/Write
0 – PTM mode is disabled
1 – PTM mode is enabled if OTP_EN_PTM=1
B1
N/A
Read/Write
B0(LSB)
N/A
Read/Write
1 – Turn off D+ voltage source to release D+ line
1 – Enter the battery detection routine
•
•
•
•
36
VOVP – Sets the OVP level
CLR_VDP – When the D+/D– detection has finished, some cases require the D+ pin to force a voltage of
0.6V. This bit allows the system to clear the voltage prior to any communication on the D+/D– pins. A ‘1’
clears the voltage at the D+ pin if present.
FORCE_BATDET – Forces battery detection and provides status of the battery presence. A logic ‘1’ enables
this function.
FORCE_PTM – Puts the device in production test mode (PTM) where the input current limit is disabled. Note
that a battery must not be present prior to using this function. Otherwise the function will not be allowed to
execute. A logic ‘1’ enables the PTM function.
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11 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.
11.1 Application Information
The bq24257EVM-150 evaluation module (EVM) is a complete charger moudule for evaluating the bq24257.
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11.2 Typical Application
Bq24257 and bq24258 devices are highly-integrated, single cell, Li-Ion battery chargers with integrated current
sense resistors targeted for space-limited, portable applications with high-capacity batteries. They are featured
with a high-efficiency switch-mode charger. They have integrated power FETs able to charge at up to a 2-A
charging rate, and an integrated 50-mA LDO. In I2C mode, the bq24257 device has programmable battery
charge voltage (VBATREG), charge current(ICHG), input current limit(ILIM), and input over-voltage protection
threshold (VOVP).
CPMID
1µF
LO
1.0PH
PMID
IN
VBUS
DD+
GND
SW
CIN
CBOOT
33 nF
2.2PF
VDPM
3 MHz
PWM
BOOT
PGND
D-
CSIN
1PF
D+
Rsns
LDO
BAT
1 PF
System Load
VGPIO
22PF
LDO
SCL
SCL
SDA
SDA
TS
TEMP
PACK+
+
Host GPIO1
STAT
PACK-
GPIO2
/CE
GPIO3
/PG
ILIM
ISET
Figure 23. bq24257 Typical Application Circuit
38
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Typical Application (continued)
11.2.1 Design Requirements
Use the following typical application design procedure to select external components values for the bq24257
device.
Table 6. Design Parameters
SPECIFICATION
Input DC voltage, VIN
Input current
Charge current
Output regulation voltage
TEST CONDITION
Recommended input voltage range
MAX
UNIT
4.35
MIN
TYP
10.5
V
2
A
0.5
2
A
Recommended input current range
Fast charge current range
Standalone mode or I2C default mode
4.2
V
2
Output regulation voltage
LDO
I C host mode: operating in voltage regulation,
programmable range
LDO output voltage
3.5
4.44
4.9
V
V
11.2.2 Detailed Design Procedure
11.2.2.1 Components Selection
The inductor selection depends on the application requirements. The bq24257 and bq24258 are designed to
operate at around 1 µH. The value has an effect on efficiency, and the ripple requirements, stability of the
charger, package size, and DCR of the inductor. The 1μH inductor provides a good tradeoff between size and
efficiency and ripple.
Once the inductance has been selected, the peak current is needed in order to choose the saturation current
rating of the inductor. Make sure that the saturation current is always greater than or equal to the calculated
IPEAK. The following equation can be used to calculate the current ripple:
ΔIL = {VBAT (VIN – VBAT)}/(VIN x ƒs x L)
(6)
Then use current ripple to calculate the peak current as follows:
IPEAK = Load x (1 + ΔIL/2)
(7)
In this design example, the regulation voltage is set to 4.2V, the input voltage is 5V and the inductance is
selected to be 1µH. The maximum charge current that can be used in this application is 1A and can be set by
I2C command. The peak current is needed in order to choose the saturation current rating of the inductor. Using
equation 6 and 7, ΔIL is calculated to be 0.224A and the inductor peak current is 1.112A. A 1µF CSIN cap is
needed and 22µF BAT cap is needed on the output trace.
The default settings for external fast charge current and external setting of current limit are chosen to be
IFC=500mA and ILIM=1A. RISET and RILIM need to be calculated using equation 1 and 2 in the data sheet.
The fast charge current resistor (RISET) can be set as follows:
RISET=250/0.5A=500Ω
The input current limit resistor (RILIM) can be set as follows:
RILIM= 270/1A=270Ω
The external settings of VIN_DPM can be designed by calculating R1 and R2 according to equation 3 in this data
sheet and the typical application circuit. VIN_DPM should be chosen first along with R1. VIN_DPM is chosen to
be 4.48V and R1 is set to 274KΩ in this design example. Using equation 3, the value of R2 is calculated to be
100 kΩ.
In this design example, the application needs to be JEITA compliant. Thus, TCOLD must be 0°C and THOT must be
60°C. If an NTC resistor is chosen such that the beta is 4500K and the nominal resistance is 13KΩ, the
calculated R3 and R4 values are 5KΩ and 8.8KΩ respectively. These results are obtained from equation 4 and 5
in this data sheet.
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11.2.3 Application Curves
ICHG = 1 A
ILIM = 1.5 A
ISYS = 0 A
VBAT = 3.6 V
ICHG = 2 A
ILIM = 0.5 A
ISYS = 0 A
VBAT = 3.6 V
VDPM = 4.36 V
Figure 25. VDPM Startup, 4.2 V
Figure 24. Startup
ICHG = 1 A
ISYS = 0 A
VBAT = 3.3 V
VIN = 5.2 V
Figure 26. 1.0-µH CCM Operation
40
Figure 27. 2-A Load Step Transient
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12 Power Supply Recommendations
The devices are designed to operate from an input voltage range between 4.35V and 10.5V. This input supply
must be well regulated. If the input supply is located more than a few inches from the bq24257 charger,
additional bulk capacitance may be required in addition to the ceramic bypass capacitors.
13 Layout
13.1 Layout Guidelines
1. Place the BOOT, PMID, IN, BAT, and LDO capacitors as close as possible to the IC for optimal performance.
2. Connect the inductor as close as possible to the SW pin, and the SYS/CSIN cap as close as possible to the
inductor minimizing noise in the path.
3. Place a 1-μF PMID capacitor as close as possible to the PMID and PGND pins, making the high frequency
current loop area as small as possible.
4. The local bypass capacitor from SYS/CSIN to GND must be connected between the SYS/CSIN pin and
PGND of the IC. This minimizes the current path loop area from the SW pin through the LC filter and back to
the PGND pin.
5. Place all decoupling capacitors close to their respective IC pins and as close as possible to PGND (do not
place components such that routing interrupts power-stage currents). All small control signals must be routed
away from the high-current paths.
6. To reduce noise coupling, use a ground plane if possible, to isolate the noisy traces from spreading its noise
all over the board. Put vias inside the PGND pads for the IC.
7. The high-current charge paths into IN, Micro-USB, BAT, SYS/CSIN, and from the SW pins must be sized
appropriately for the maximum charge current to avoid voltage drops in these traces.
8. For high-current applications, the balls for the power paths must be connected to as much copper in the
board as possible. This allows better thermal performance because the board conducts heat away from the
IC.
13.2 Layout Example
Figure 28. Recommended bq2425x PCB Layout for WCSP Package
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13.3 Device and Documentation Support
13.3.1 Related Links
The table below lists quick access links. Categories include technical documents, support and community
resources, tools and software, and quick access to sample or buy.
Table 7. Related Links
PARTS
PRODUCT FOLDER
SAMPLE & BUY
TECHNICAL
DOCUMENTS
TOOLS &
SOFTWARE
SUPPORT &
COMMUNITY
bq24257
Click here
Click here
Click here
Click here
Click here
bq24258
Click here
Click here
Click here
Click here
Click here
14 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.
42
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PACKAGE OPTION ADDENDUM
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10-Dec-2020
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)
BQ24257RGER
NRND
VQFN
RGE
24
3000
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 85
BQ24257
BQ24257RGET
NRND
VQFN
RGE
24
250
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 85
BQ24257
BQ24257YFFR
NRND
DSBGA
YFF
30
3000
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
-40 to 85
BQ24257
BQ24257YFFT
NRND
DSBGA
YFF
30
250
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
-40 to 85
BQ24257
(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
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