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bq24070, bq24071
SLUS694G – MARCH 2006 – REVISED DECEMBER 2014
bq2407x Single-Chip Li-Ion Charge and System Power-Path Management IC
1 Features
3 Description
•
•
The bq24070 and bq24071 are highly integrated Liion linear charger and system power-path
management devices targeted at space-limited
portable applications. The bq2407x devices offer DC
supply (AC adapter) power-path management with
autonomous power-source selection, power FETs
and current sensors, high-accuracy current and
voltage regulation, charge status, and charge
termination, in a single monolithic device.
1
•
•
•
•
•
•
•
•
•
Small 3.5-mm × 4.5-mm VQFN Package
Designed for Single-Cell Li-Ion- or Li-PolymerBased Portable Applications
Integrated Dynamic Power-Path Management
(DPPM) Feature Allowing the AC Adapter to
Simultaneously Power the System and Charge the
Battery
Power Supplement Mode Allows Battery to
Supplement the AC Input Current
Autonomous Power Source Selection (AC Adapter
or BAT)
Supports Up to 2 A Total Current
Thermal Regulation for Charge Control
Charge Status Outputs for LED or System
Interface Indicates Charge and Fault Conditions
Reverse Current, Short-Circuit, and Thermal
Protection
Power Good Status Outputs
4.4-V and 6-V Options for System Output
Regulation Voltage
The bq2407x devices power the system while
independently charging the battery. This feature
reduces the charge and discharge cycles on the
battery, allows for proper charge termination, and
allows the system to run with an absent or defective
battery pack. This feature also allows for the system
to instantaneously turn on from an external power
source in the case of a deeply discharged battery
pack. The IC design is focused on supplying
continuous power to the system when available from
the AC adapter or battery sources.
Device Information(1)
PART NUMBER
bq24070
PACKAGE
BODY SIZE (NOM)
VQFN (20)
3.50 mm × 4.50 mm
2 Applications
bq24071
•
•
•
•
(1) For all available packages, see the orderable addendum at
the end of the datasheet.
Smart Phones and PDAs
MP3 Players
Digital Cameras and Handheld Devices
Internet Appliances
Simplified Schematic(1)
AC Adapter
(2)
IN
OUT
VDC
GND
System
Q1
40 mΩ
BAT
PACK+
+
PACK−
bq24070/1
Q2
UDG−04082
(1)
See Figure 2 and Functional Block Diagram for more detailed feature information.
(2)
P-FET back gate body diodes are disconnected to prevent body diode conduction.
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.
bq24070, bq24071
SLUS694G – MARCH 2006 – REVISED DECEMBER 2014
www.ti.com
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
5
5
8
Absolute Maximum Ratings .....................................
ESD Ratings..............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Typical Characteristics ..............................................
Detailed Description .............................................. 9
8.1 Overview ................................................................... 9
8.2 Functional Block Diagram ....................................... 10
8.3 Feature Description................................................. 11
8.4 Device Functional Modes........................................ 14
9
Application and Implementation ........................ 20
9.1 Application Information............................................ 20
9.2 Typical Application .................................................. 20
10 Power Supply Recommendations ..................... 23
11 Layout................................................................... 23
11.1 Layout Guidelines ................................................. 23
11.2 Layout Example .................................................... 23
11.3 Thermal Considerations ........................................ 24
12 Device and Documentation Support ................. 25
12.1
12.2
12.3
12.4
12.5
Documentation Support ........................................
Related Links ........................................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
25
25
25
25
25
13 Mechanical, Packaging, and Orderable
Information ........................................................... 25
4 Revision History
Changes from Revision F (December 2009) to Revision G
•
2
Page
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
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SLUS694G – MARCH 2006 – REVISED DECEMBER 2014
5 Device Comparison Table
PART
NUMBER
bq24070
bq24071
(1)
(2)
TA
BATTERY
VOLTAGE (V)
–40°C to 125°C
4.2
(1)
OUT PIN
STATUS
Regulated to 4.4 V (2)
Production
Regulated to 6 V
PACKAGE
MARKING
BRQ
BTR
This product is RoHS compatible, including a lead concentration that does not exceed 0.1% of total product weight, and is suitable for
use in specified lead-free soldering processes. In addition, this product uses package materials that do not contain halogens, including
bromine (Br) or antimony (Sb) above 0.1% of total product weight.
If IN < VO(OUT-REG), the IN is connected to the OUT pin by a P-FET, (Q1).
6 Pin Configuration and Functions
GND
VREF
RHL Package
20 Pins
Top View
STAT1
2
STAT2
3
18
PG
IN
4
17
OUT
BAT
5
16
OUT
BAT
6
15
OUT
ISET2
7
14
TMR
MODE
8
13
DPPM
20 19
11 12
GND
TS
VSS
9 10
ISET1
CE
1
Pin Functions
PIN
I/O
DESCRIPTION
NAME
NO.
BAT
5, 6
I/O
CE
9
I
Chip enable input (active high)
DPPM
Battery input and output.
13
I
Dynamic power-path management set point (account for scale factor)
19, 20
I
Ground input
IN
4
I
Charge input voltage
ISET1
10
I/O
ISET2
7
I
Charge current set point for USB port. (High = 500 mA, Low = 100 mA) See half-charge current mode
using ISET2.
MODE
8
I
Power source selection input (Low for USB mode current limit)
GND
OUT
Charge current set point and precharge and termination set point
15, 16, 17
O
Output terminal to the system
PG
18
O
Power-good status output (open-drain)
STAT1
2
O
Charge status output 1 (open-drain)
STAT2
3
O
Charge status output 2 (open-drain)
TMR
14
I/O
Timer program input programmed by resistor. Disable fast-charge safety timer and termination by tying
TMR to VREF.
TS
12
I/O
Temperature sense input
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Pin Functions (continued)
PIN
I/O
DESCRIPTION
NAME
NO.
VREF
1
O
Internal reference signal
VSS
11
–
Ground input (the thermal pad on the underside of the package) There is an internal electrical connection
between the exposed thermal pad and VSS pin of the device. The exposed 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.
7 Specifications
7.1 Absolute Maximum Ratings (1)
over operating free-air temperature range (unless otherwise noted)
Input voltage
Input voltage
MIN
MAX
IN (DC voltage with respect to VSS)
–0.3
18
BAT, CE, DPPM, PG, Mode, OUT, ISET1, ISET2, STAT1, STAT2, TS, (all DC
voltages with respect to VSS)
–0.3
7
VREF (DC voltage with respect to VSS)
–0.3
VO(OUT) +
0.3
TMR
–0.3
VO + 0.3
Input current
Output current
UNIT
V
3.5
OUT
4
BAT (2)
–4
A
3.5
Output source
current (in
regulation at
3.3-V VREF)
VREF
30
mA
Output sink
current
PG, STAT1, STAT2,
15
mA
Junction temperature, TJ
–40
Lead temperature (soldering, 10 s)
300
Storage temperature, Tstg
(1)
(2)
150
–65
°C
150
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating
Conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. All voltage
values are with respect to the network ground terminal unless otherwise noted.
Negative current is defined as current flowing into the BAT pin.
7.2 ESD Ratings
VALUE
V(ESD)
(1)
(2)
Electrostatic discharge
Human body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1)
±1000
Charged-device model (CDM), per JEDEC specification JESD22C101 (2)
±250
UNIT
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. Manufacturing with
less than 500-V HBM is possible with the necessary precautions. Pins listed as ±XXX V may actually have higher performance.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process. Manufacturing with
less than 250-V CDM is possible with the necessary precautions. Pins listed as ±YYY V may actually have higher performance.
7.3 Recommended Operating Conditions
(1)
VCC
Supply voltage (VIN)
IIN
Input current
TJ
Operating junction temperature range
(1)
4
MIN
MAX
4.35
16
–40
UNIT
V
2
A
125
°C
Verify that power dissipation and junction temperatures are within limits at maximum VCC .
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SLUS694G – MARCH 2006 – REVISED DECEMBER 2014
7.4 Thermal Information
bq2407x
THERMAL METRIC (1)
RHL
UNIT
20 PINS
RθJA
Junction-to-ambient thermal resistance
40.1
RθJC(top)
Junction-to-case (top) thermal resistance
42.0
RθJB
Junction-to-board thermal resistance
16.6
ψJT
Junction-to-top characterization parameter
0.7
ψJB
Junction-to-board characterization parameter
16.6
RθJC(bot)
Junction-to-case (bottom) thermal resistance
4.2
(1)
°C/W
For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.
7.5 Electrical Characteristics
over junction temperature range (0°C ≤ TJ ≤ 125°C) and the recommended supply voltage range (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
INPUT BIAS CURRENTS
ICC(SPLY)
Active supply current, VCC
VVCC > VVCC(min)
1
2
ICC(SLP)
Sleep current (current into BAT
pin)
VIN < V(BAT)
2.6 V ≤ VI(BAT) ≤ VO(BAT-REG),
Excludes load on OUT pin
2
5
ICC(IN-STDBY)
Input standby current
VI(IN) ≤ 6V, Total current into IN pin with chip
disabled, Excludes all loads, CE=LOW, after
t(CE-HOLDOFF) delay
ICC(BAT-STDBY)
BAT standby current
Total current into BAT pin with input present
and chip disabled;
Excludes all loads, CE=LOW,
after t(CE-HOLDOFF) delay,
0°C ≤ TJ ≤ 85°C (1)
IIB(BAT)
Charge done current, BAT
Charge DONE, input supplying the load
mA
200
μA
45
65
1
5
OUT PIN-VOLTAGE REGULATION
VO(OUT-REG)
Output regulation
voltage
bq24070
VI(IN) ≥ 4.4 V + VDO
4.4
4.5
bq24071
VI(IN) ≥ 6 V + VDO
6.0
6.3
V
OUT PIN – DPPM REGULATION
V(DPPM-SET)
DPPM set point (2)
VDPPM-SET < VOUT
2.6
3.8
V
I(DPPM-SET)
DPPM current source
Input present
95
100
105
μA
SF
DPPM scale factor
V(DPPM-REG) = V(DPPM-SET) × SF
1.139
1.150
1.162
300
475
40
100
OUT PIN – FET (Q1, Q2) DROP-OUT VOLTAGE RDS(on))
V(INDO)
IN-to-OUT dropout voltage (3)
VI(IN) ≥ VCC(min), Mode = High,
II(IN) = 1 A, (IO(OUT)+ IO(BAT)), or no input
V(BATDO)
BAT-to-OUT dropout voltage
(discharging)
VI
(1)
(2)
(3)
(BAT)
≥ 3 V, II(BAT)= 1.0 A, VCC < VI(BAT)
mV
This includes the quiescent current for the integrated LDO.
V(DPPM-SET) is scaled up by the scale factor for controlling the output voltage V(DPPM-REG).
VDO(max), dropout voltage is a function of the FET, RDS(on), and drain current. The dropout voltage increases proportionally to the
increase in current.
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Electrical Characteristics (continued)
over junction temperature range (0°C ≤ TJ ≤ 125°C) and the recommended supply voltage range (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
OUT PIN - BATTERY SUPPLEMENT MODE
VBSUP1
Enter battery supplement mode
(battery supplements OUT current
in the presence of input source
VI(BAT)> 2 V
VBSUP2
Exit battery supplement mode
VI(BAT)> 2 V
VI(OUT)
≤ VI(BAT)
– 60 mV
VI(OUT)
≥ VI(BAT)
– 20 mV
V
OUT PIN - SHORT CIRCUIT
IOSH1
BAT to OUT short-circuit recovery
Current source between BAT to OUT for
short-circuit recovery to
VI(OUT) ≤ VI(BAT) –200 mV
RSHIN
IN to OUT short-circuit limit
VI(OUT) ≤ 1 V
10
mA
500
Ω
BAT PIN CHARGING – PRECHARGE
V(LOWV)
Precharge to fast-charge transition
threshold
Voltage on BAT
TDGL(F)
Deglitch time for fast-charge to
precharge transition (4)
tFALL = 100 ns, 10 mV overdrive,
VI(BAT) decreasing below threshold
IO(PRECHG)
Precharge range
1 V < VI(BAT) < V(LOWV), t < t(PRECHG),
IO(PRECHG) = (K(SET) × V(PRECHG))/ RSET
V(PRECHG)
Precharge set voltage
1 V < VI(BAT) < V(LOWV), t < t(PRECHG)
225
100
2.9
3
3.1
22.5
V
ms
10
150
mA
250
275
mV
1000
1500
mA
BAT PIN CHARGING - CURRENT REGULATION
IO(BAT)
Battery charge current range (5)
VI (BAT) > V(LOWV), Mode = High
IOUT(BAT) = (K(SET) × V(SET) / RSET),
VI(OUT) > VO(OUT-REG) + V(DO-MAX)
RPBAT
BAT to OUT pullup
VI
V(SET)
Battery charge current set
voltage (6)
Voltage on ISET1, VVCC ≥ 4.35 V,
VI(OUT)- VI(BAT) > V(DO-MAX),
VI(BAT) > V(LOWV)
2.47
2.50
2.53
K(SET)
Charge current set factor, BAT
100 mA ≤ IO(BAT) ≤ 1.5 A
375
425
450
10 mA ≤ IO(BAT) ≤ 100 mA (7)
300
450
600
(BAT)<
1V
Ω
1000
V
USB MODE INPUT CURRENT LIMIT
I(USB)
USB input port current range
ISET2 = Low
80
ISET2 = High
400
90
100
mA
500
BAT PIN CHARGING VOLTAGE REGULATION, VO (BAT-REG) + V (DO-MAX) < VCC, ITERM < IBAT(OUT) ≤ 1 A
Battery charge voltage
VO(BAT-REG)
4.2
TA = 25°C
Battery charge voltage regulation
accuracy
V
–0.5%
0.5%
–1%
1%
10
150
CHARGE TERMINATION DETECTION
I(TERM)
Charge termination detection
range
VI(BAT) > V(RCH),
I(TERM) = (K(SET) × V(TERM))/ RSET
V(TERM)
Charge termination set voltage,
measured on ISET1
VI(BAT) > V(RCH) , Mode = High
230
250
270
VI(BAT) > V(RCH) , Mode = Low
95
100
130
TDGL(TERM)
Deglitch time for termination
detection
tFALL = 100 ns, 10 mV overdrive,
ICHG increasing above or decreasing below
threshold
22.5
mA
mV
ms
TEMPERATURE SENSE COMPARATORS
VLTF
High voltage threshold
Temp fault at V(TS) > VLTF
2.465
2.500
2.535
VHTF
Low voltage threshold
Temp fault at V(TS) < VHTF
0.485
0.500
0.515
V
ITS
Temperature sense current source
94
100
106
μA
TDGL(TF)
Deglitch time for temperature fault
detection (4)
(4)
(5)
(6)
(7)
6
R(TMR) = 50 kΩ, VI(BAT) increasing or
decreasing above and below;
100-ns fall time, 10-mv overdrive
22.5
V
ms
All deglitch periods are a function of the timer setting and is modified in DPPM or thermal regulation modes by the percentages that the
program current is reduced.
When input current remains below 2 A, the battery charging current may be raised until the thermal regulation limits the charge current.
For half-charge rate, V(SET) is 1.25 V ± 25 mV.
Specification is for monitoring charge current through the ISET1 pin during voltage regulation mode, not for a reduced fast-charge level.
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Electrical Characteristics (continued)
over junction temperature range (0°C ≤ TJ ≤ 125°C) and the recommended supply voltage range (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
VO(BAT-REG)
–0.100
VO(BAT-REG)
–0.125
UNIT
BATTERY RECHARGE THRESHOLD
VO(BATVRCH
Recharge threshold voltage
REG)
–0.075
R(TMR) = 50 kΩ, VI(BAT) increasing
or decreasing below threshold,
100-ns fall time, 10-mv overdrive
Deglitch time for recharge
detection (4)
TDGL(RCH)
22.5
V
ms
STAT1, STAT2, AND PG, OPEN-DRAIN (OD) OUTPUTS (8)
VOL
Low-level output saturation voltage
ILKG
Input leakage current
IOL = 5 mA, An external pullup
resistor ≥ 1 K required.
1
0.25
V
5
μA
ISET2, CE INPUTS
VIL
Low-level input voltage
0
VIH
High-level input voltage
1.4
IIL
Low-level input current, CE
–1
IIH
High-level input current, CE
IIL
Low-level input current, ISET2
VISET2 = 0.4 V
IIH
High-level input current, ISET2
VISET2 = VCC
t(CE-HLDOFF)
Holdoff time, CE
CE going low only
VIL
Low-level input voltage
Falling Hi→Low; 280 K ± 10% applied when
low.
VIH
High-level input voltage
Input RMode sets external hysteresis
IIL
Low-level input current, Mode
0.4
1
–20
V
μA
40
3.3
6.2
ms
MODE INPUT
0.975
1
VIL + .01
1.025
VIL + .024
V
V
μA
–1
TIMERS
K(TMR)
R(TMR)
Timer set factor
(9)
t(CHG) = K(TMR) × R(TMR)
External resistor limits
t(PRECHG)
Precharge timer
I(FAULT)
Timer fault recovery pullup from
OUT to BAT
0.313
0.414
s/Ω
30
0.360
100
kΩ
0.09 ×
t(CHG)
0.10 × t(CHG) 0.11 × t(CHG)
1
s
kΩ
CHARGER SLEEP THRESHOLDS (PG THRESHOLDS, LOW → POWER GOOD)
V(SLPENT)
(10)
Sleep-mode entry threshold
V(UVLO) ≤ VI(BAT) ≤ VO(BAT-REG),
No t(BOOT-UP) delay
V(SLPEXIT)
(10)
Sleep-mode exit threshold
V(UVLO) ≤ VI(BAT) ≤ VO(BAT-REG),
No t(BOOT-UP) delay
Deglitch time for sleep mode (11)
R(TMR) = 50 kΩ,
V(IN) decreasing below threshold, 100-ns fall
time, 10-mv overdrive
t(DEGL)
VVCC ≤
VI(BAT)
+125 mV
VVCC ≥
VI(BAT)
+190 mV
22.5
V
ms
START-UP CONTROL BOOT-UP
t(BOOT-UP)
Boot-up time
On the first application of input with Mode
Low
120
150
180
ms
(8)
(9)
See Charger Sleep mode for PG (VCC = VIN) specifications.
To disable the fast-charge safety timer and charge termination, tie TMR to the VREF pin. Tying the TMR pin high changes the timing
resistor from the external value to an internal 50 kΩ ±25%, which can add an additional tolerance to any timed specification. The TMR
pin normally regulates to 2.5 V when the charge current is not restricted by the DPPM or thermal feedback loops. If these loops become
active, the TMR pin voltage will be reduced proportionally to the reduction in charge current and the clock frequency will be reduced by
the same percentage (timed durations will count down slower, extending their time). The TMR pin is clamped at 0.80 V, for a maximum
time extension of 2.5 V ÷ 0.8 V × 100 = 310%.
(10) The IC is considered in sleep mode when IN is absent (PG = OPEN DRAIN).
(11) Does not declare sleep mode until after the deglitch time and implement the needed power transfer immediately according to the
switching specification.
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Electrical Characteristics (continued)
over junction temperature range (0°C ≤ TJ ≤ 125°C) and the recommended supply voltage range (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
SWITCHING POWER SOURCE TIMING
Switching power source from input
to battery
tSW-BAT
When input applied. Measure from:
[PG: Lo → Hi to I(IN) > 5 mA],
I(OUT) = 100 mA,
RTRM = 50 K
50
μs
THERMAL SHUTDOWN REGULATION (12)
T(SHTDWN)
TJ(REG)
Temperature trip
TJ (Q1 and Q3 only)
Thermal hysteresis
TJ (Q1 and Q3 only)
155
Temperature regulation limit
TJ (Q2)
115
Undervoltage lockout
Decreasing VCC
2.45
30
°C
135
UVLO
V(UVLO)
2.50
Hysteresis
2.65
V
27
mV
3.3
V
VREF OUTPUT
VO(VREF)
Regulation accuracy
IO(VREF)
Output current
RDS(on)
On resistance
C(OUT)
Active only if IN or USB is present,
VI(OUT) ≥ VO(VREF) + (IO(VREF) × RDS(on))
Output regulation voltage
(14)
(13)
–5%
5%
20
OUT to VREF
Output capacitance
mA
50
Ω
1
μF
(12) Reaching thermal regulation reduces the charging current. Battery supplement current is not restricted by either thermal regulation or
shutdown. Input power FETs turn off during thermal shutdown. The battery FET is only protected by a short-circuit limit which typically
does not cause a thermal shutdown (input FETs turning off) by itself.
(13) In standby mode (CE low) the accuracy is ±10%.
(14) VREF output capacitor not required, but one with a value of 0.1 μF is recommended.
7.6 Typical Characteristics
4.44
VOUT, VAC = 5.5 V
II = 100 A
+3 Sigma
4.42
Voltage - V
4.4
Mean
4.38
4.36
-3 Sigma
4.34
4.32
-60
-40
-20
0
20
40
60
80
100
120
140
o
T - Temperatures - C
Figure 1. SIGMA Typical OUT Voltage Regulation, bq24070
8
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8 Detailed Description
8.1 Overview
The bq2407x device is a highly-integrated Li-ion linear charger and system power-path management device
targeted at space-limited portable applications. The bq2407x devices offer DC supply (AC adapter) power-path
management with autonomous power-source selection, power FETs and current sensors, high-accuracy current
and voltage regulation, charge status, and charge termination, in a single monolithic device.
The bq2407x devices support a precision Li-ion or Li-polymer charging system suitable for single-cell portable
devices. See a typical charge profile, application circuits, and an operational flow chart in Figure 2 through
Figure 6, respectively.
Pre-Conditioning
Phase
Current Regulation Phase
Voltage Regulation and Charge Termination Phase
Regulation
Voltage
Regulation
Current
Minimum
Charge
Voltage
Pre−
Conditioning
and Term
Detect
Charge
Voltage
Charge
Complete
Charge
Current
UDG−04087
Figure 2. Charge Profile
The bq2407x devices power the system while independently charging the battery. This feature reduces the
charge and discharge cycles on the battery, allows for proper charge termination and allows the system to run
with an absent or defective battery pack. This feature also allows for the system to instantaneously turn on from
an external power source in the case of a deeply discharged battery pack. The IC design is focused on supplying
continuous power to the system when available from the AC adapter or battery sources.
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8.2 Functional Block Diagram
Short−Circuit Recovery
500 Ω
BAT
Short−Circuit
Recovery
100 mA /
500 mA
IN
VO(OUT)
OUT
Q1
1 kΩ
Fault
Recovery
3.3 V
VREF
10 mA
VSET
+
I(SNS)
VIO(AC)
AC Charge
Enable VI (SNS)
VO(OUT)
GND
Q2
VI(BAT)
BAT
+
VO(OUT−REG)
VI(ISET1)
ISET1
UVLO
VO(BAT−REG)
TMR
Oscillator
VI(BAT)
VI(BAT)
+
VO(BAT−REG)
VI(ISET1)
VO(OUT)
DPPM
+
DPPM
I(DPPM) Scaling
VDPPM
+
Disable−
Sleep
+
VI(BAT)
200 mV
Suspend
Thermal
Shutdown
1V
+
I(TS)
TS
+
VO(OUT)
TJ(REG)
*
60 mV
+
TJ
V(HTF)
BAT
Charge
Enable
VSET
+
1V
+
Fast Precharge
+
*
V(LTF)
280 kΩ
Power Source Selection
MODE
AC Charge Enable
CE
BAT Charge Enable
VO(BAT−REG)
Recharge
VBAT
*
Precharge
VBAT
Charge
Control
Timer
and
Display
Logic
500 mA/ 100 mA
Fast Precharge
1C − 500 mA
C/S − 100 mA
ISET2
*
PG
V(SET)
VI(ISET1)
Term
GND
*
STAT1
Sleep
VBAT
VIN
*
STAT2
VSS
*
Signal Deglitched
UDG−04084
10
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8.3 Feature Description
8.3.1 Power-Path Management
The bq2407x devices power the system while independently charging the battery. This feature reduces the
charge and discharge cycles on the battery, allows for proper charge termination, and allows the system to run
with an absent or defective battery pack. This feature gives the system priority on input power, allowing the
system to power up with a deeply discharged battery pack. This feature works as follows:
AC Adapter
(2)
IN
OUT
VDC
GND
System
Q1
40 mΩ
BAT
PACK+
+
PACK−
bq24070/1
Q2
UDG−04082
Figure 3. Power-Path Management
8.3.1.1 Case 1: IN Mode (Mode = High)
8.3.1.1.1 System Power
In this case, the system load is powered directly from the AC adapter through the internal transistor Q1 (see
Figure 3). The output is regulated at 4.4 V (bq24070). If the system load exceeds the capacity of the supply, the
output voltage drops down to the voltage of the battery.
8.3.1.1.2 Charge Control
When in IN mode, the battery is charged through switch Q2 based on the charge rate set on the ISET1 input.
8.3.1.1.3 Dynamic Power-Path Management (DPPM)
This feature monitors the output voltage (system voltage) for input power loss due to brown outs, current limiting,
or removal of the input supply. If the voltage on the OUT pin drops to a preset value, V(DPPM) × SF, due to a
limited amount of input current, then the battery charging current is reduced until the output voltage stops
dropping. The DPPM control tries to reach a steady-state condition where the system gets its needed current and
the battery is charged with the remaining current. No active control limits the current to the system; therefore, if
the system demands more current than the input can provide, the output voltage drops just below the battery
voltage and Q2 turns on which supplements the input current to the system. DPPM has three main advantages.
1. This feature allows the designer to select a lower power wall adapter, if the average system load is moderate
compared to its peak power. For example, if the peak system load is 1.75 A, average system load is 0.5 A
and battery fast-charge current is 1.25 A, the total peak demand could be 3 A. With DPPM, a 2-A adaptor
could be selected instead of a 3.25-A supply. During the system peak load of 1.75 A and charge load of 1.25
A, the smaller adaptor’s voltage drops until the output voltage reaches the DPPM regulation voltage
threshold. The charge current is reduced until there is no further drop on the output voltage. The system gets
its 1.75-A charge and the battery charge current is reduced from 1.25 A to 0.25 A. When the peak system
load drops to 0.5 A, the charge current returns to 1 A and the output voltage returns to its normal value.
2. Using DPPM provides a power savings compared to configurations without DPPM. Without DPPM, if the
system current plus charge current exceed the supply’s current limit, then the output is pulled down to the
battery. Linear chargers dissipate the unused power (VIN-VOUT) × ILOAD. The current remains high (at current
limit) and the voltage drop is large for maximum power dissipation. With DPPM, the voltage drop is less (VINV(DPPM-REG)) to the system which means better efficiency. The efficiency for charging the battery is the same
for both cases. The advantages include less power dissipation, lower system temperature, and better overall
efficiency.
3. If possible, the DPPM sustains the system voltage no matter what causes it to drop. The DPPM does this by
reducing the noncritical charging load while maintaining the maximum power output of the adaptor.
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Feature Description (continued)
The DPPM voltage, V(DPPM), is programmed as follows:
V (DPPM−REG) = I (DPPM) × R(DPPM) × SF
where
•
•
•
R(DPPM) is the external resistor connected between the DPPM and VSS pins
I(DPPM) is the internal current source
SF is the scale factor as specified in the specification table
(1)
The safety timer is dynamically adjusted while in DPPM mode. The voltage on the ISET1 pin is directly
proportional to the programmed charging current. When the programmed charging current is reduced, due to
DPPM, the ISET1 and TMR voltages are reduced and the timer clock is proportionally slowed, extending the
safety time. In normal operation V(TMR) = 2.5 V; and, when the clock is slowed, V(TMR) is reduced. When
V(TMR) = 1.25 V, the safety timer has a value close to 2 times the normal operation timer value. See Figure 10
through Figure 9.
8.3.1.2 Case 2: USB Mode (Mode = L)
8.3.1.2.1 System Power
In this case, the system load is powered from a USB port through the internal switch Q1 (see Figure 3). In this
case, Q1 regulates the total current to the 100-mA or 500-mA level, as selected on the ISET2 input. The output,
VOUT, is regulated to 4.4 V (bq24070). The power management of the system is responsible for keeping its
system load below the USB current level selected (if the battery is critically low or missing). Otherwise, the output
drops to the battery voltage; therefore, the system should have a low-power mode for USB power application.
The DPPM feature keeps the output from dropping below its programmed threshold, due to the battery charging
current, by reducing the charging current.
8.3.1.2.2 Charge Control
When in USB mode, Q1 regulates the input current to the value selected by the ISET2 pin (0.1/0.5 A). The
charge current to the battery is set by the ISET1 resistor (typically > 0.5 A). Because the charge current typically
is programmed for more current than the USB current limit allows, the output voltage drops to the battery voltage
or DPPM voltage, whichever is higher. If the DPPM threshold is reached first, the charge current is reduced until
VOUT stops dropping. If VOUT drops to the battery voltage, the battery is able to supplement the input current to
the system.
8.3.1.2.3 Dynamic Power-Path Management (DPPM)
The theory of operation is the same as described in CASE 1, except that Q1 is restricted to the USB current level
selected by the ISET2 pin.
The DPPM voltage, V(DPPM), is programmed as follows:
V (DPPM−REG) = I (DPPM) × R(DPPM) × SF
where
•
•
•
R(DPPM) is the external resistor connected between the DPPM and VSS pins
I(DPPM) is the internal current source
SF is the scale factor as specified in the specification table
(2)
8.3.1.2.4 Application Curve Descriptions
Refer to the applications section to view the curves. Figure 10 illustrates DPPM and battery supplement modes
as the output current (IOUT) is increased; channel 1 (CH1) VIN (VAC) = 5.4 V; channel 2 (CH2) VOUT; channel 3
(CH3) IOUT = 0 to 2.2 A to 0 A; channel 4 (CH4) VBAT = 3.5 V; I(PGM-CHG) = 1 A. The output load is increased from
0 A to approximately 2.2 A and back to 0 A as shown in the bottom waveform. As the IOUT load reaches 0.5 A,
along with the 1-A charge current, the adaptor starts to current limit, the output voltage drops to the DPPM-OUT
threshold of 4.26 V. This is DPPM mode. The IN input tracks the output voltage by the dropout voltage of the IN
FET. The battery charge current is then adjusted back as necessary to keep the output voltage from falling any
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Feature Description (continued)
further. Once the output load current exceeds the input current, the battery has to supplement the excess current
and the output voltage falls just below the battery voltage by the dropout voltage of the battery FET. This is the
battery supplement mode. When the output load current is reduced, the operation described is reversed as
shown. If the DPPM-OUT voltage was set below the battery voltage, during input current limiting, the output falls
directly to the battery's voltage.
Under USB operation, when the loads exceeds the programmed input current thresholds a similar pattern is
observed. If the output load exceeds the available USB current, the output instantly goes into the battery
supplement mode.
Figure 8 illustrates when a battery is inserted for power up; channel 1 (CH1) VIN = 0 V; channel 2 (CH2) VUSB =
0 V; channel 3 (CH3) VOUT; output current, IOUT = 0.25 A for VOUT > 2 V; channel 4 (CH4) VBAT = 3.5 V; C(DPPM) =
0 pF. When there are no power sources and the battery is inserted, the output tracks the battery voltage if there
is no load ( 1 V × 500 Ω/ (Vin–Vout)} such that the pullup
resistor is able to lift the output voltage above 1 V, for the input FET to be turned back on.
If the output drops 200 mV below the battery voltage, the battery FET, Q2 is considered in short circuit and the
battery FET turns off. To recover from this state, there is a 10-mA current source from the battery to the output.
Once the output load is reduced, such that the 10-mA current source can pick up the output within 200 mV of the
battery, the FET turns back on.
If the short is removed, and the minimum system load is still too large [R VI(BAT), Battery Present, CE pin = High and DPPM Pin Not Floating
8.4.3.1 Automous Power Selection and Boot-Up Sequence
The MODE control pin selects the priority of the input sources. If an input source is not available, the battery is
selected as the source. With the MODE pin high, the bq2407x charges from the input at the charge rate set by
the ISET1 pin. With the MODE pin low, the bq2407x defaults to the USB charging at the charge rate, and the
supply current is limited by the ISET2 pin (100 mA for ISET2 = Low, 500 mA for ISET2 = High). This feature
allows the use of a single connector (mini-USB cable), where the host programs the MODE pin according to the
source that is connected (AC adaptor or USB port). Table 2 summarizes the MODE pin function.
Table 2. Power Source Selection Function Summary
MODE STATE
AC
ADAPTER
MAXIMUM
CHARGE RATE (1)
Low
Present
ISET2
USB
Enabled
Absent
N/A
Battery
Disabled
Present
ISET1
IN
Disabled
Absent
N/A
Battery
Disabled
High
(1)
SYSTEM
POWER
SOURCE
USB BOOT-UP
FEATURE
Battery charge rate is always set by ISET1, but may be reduced by a limited input source (ISET2 USB mode) and IOUT system load.
With Mode= Low, in order to facilitate the system start-up and USB enumeration, the bq2407x offers a
proprietary boot-up sequence. On the first application of power to the bq2407x, this feature enables the 100-mA
USB charge rate for a period of approximately 150 ms, (t(BOOT-UP)), ignoring the ISET2 and CE inputs setting.
At the end of this period, the bq2407x implement CE and ISET2 input settings. See Figure 9.
V(OUT) is regulated to VO(OUT-REG) as long as the the system load, I(SYS), plus the battery charge current, IO(BAT),
set by ISET1 does not exceed the maximum input current of
IIN = 2 A if MODE is high or
IIN set by ISET2 if MODE is low.
If V(OUT) drops to the DPPM pin preset value, V(DPPM) × SF, due to a limited amount of input current, then the
battery charging current is dynamically reduced until the output voltage stops dropping. If the system demands
more current than the input can provide, the output voltage drops just below the battery voltage and Q2 turns on
which allows the battery to supplement the input current to the system. The DPPM circuity is explained in detail
in Power-Path Management. The following sections explain the battery charge process in detail. Floating the
DPPM pin disables battery charging.
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8.4.3.2 Charge Control
POR
SLEEP MODE
Vcc > VI(BAT)
checked at all
times?
No
Indicate SLEEP
MODE
Yes
V I(BAT) < V(LOWV)
Yes
Regulate
I O(PRECHG)
Reset and Start
t(PRECHG) timer
Indicate Charge−
In−Progress
?
No
Reset all timers,
Start t (CHG) timer
Regulate Current
or V oltage
Indicate Charge−
In−Progress
No
V I(BAT)
V(RCH)
?
T urn off charge
Yes
Yes
Indicate DONE
Disable I (F AUL T)
No
current
V I(BAT) < V(RCH)
?
Figure 6. Charge Control Operational Flow Chart
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8.4.3.3 Battery Preconditioning
During a charge cycle, if the battery voltage is below the V(LOWV) threshold, the bq2407x applies a precharge
current, IO(PRECHG), to the battery. This feature revives deeply discharged cells. The RSET resistor, connected
between the ISET1 and VSS pins, determines the precharge rate. The V(PRECHG) and K(SET) parameters are
specified in the specifications table. Note that this applies to both IN-mode and USB-mode charging.
V(PRECHG) × K(SET)
I O (PRECHG) =
RSET
(3)
The bq2407x activates a safety timer, t(PRECHG), during the conditioning phase. If V(LOWV) threshold is not reached
within the timer period, the bq2407x turns off the charger and enunciates FAULT on the STAT1 and STAT2 pins.
The time-out is extended if the charge current is reduced by DPPM or thermal regulation. See the Timer Fault
Recovery section for additional details.
8.4.3.4 Battery Charge Current
The bq2407x offers on-chip current regulation with programmable set point. The RSET resistor, connected
between the ISET1 and VSS pins, determines the charge level. The charge level may be reduced to give the
system priority on input current (see DPPM). The V(SET) and K(SET) parameters are specified in the specifications
table.
V(SET) × K(SET)
I O (OUT) =
RSET
(4)
When powered from a USB port, the input current available (0.1 A/0.5 A) is typically less than the programmed
(ISET1) charging current, and therefore, the DPPM feature attempts to keep the output from being pulled down
by reducing the charging current.
The charge level, during IN mode operation only (Mode = High), can be changed by a factor of 2 by setting the
ISET2 pin high (full charge) or low (half charge). The voltage on the ISET1 pin, VSET1, is divided by 2 when in
the half constant current charge mode. Note that with Mode low, the ISET2 pin controls only the 0.1 A/0.5 A USB
current level.
See Power-Path Management for additional details.
8.4.3.5 Battery Voltage Regulation
The voltage regulation feedback is through the BAT pin. This input is tied directly to the positive side of the
battery pack. The bq2407x monitors the battery-pack voltage between the BAT and VSS pins. When the battery
voltage rises to the VO(REG) threshold, the voltage regulation phase begins and the charging current begins to
taper down.
If the battery is absent, the BAT pin cycles between charge done (VO(REG)) and charging (battery recharge
threshold, approximately 4.1 V).
See Figure 8 for power up by battery insertion.
As a safety backup, the bq2407x also monitors the charge time in the charge mode. If charge is not terminated
within this time period, t(CHG), the bq2407x turns off the charger and enunciates FAULT on the STAT1 and
STAT2 pins. See the DPPM operation under Case 1 for information on extending the safety timer during DPPM
operation. See the Timer Fault Recovery section for additional details.
8.4.3.6 Temperature Regulation and Thermal Protection
To maximize charge rate, the bq2407x features a junction temperature regulation loop. If the power dissipation of
the IC results in a junction temperature greater than the TJ(REG) threshold, the bq2407x throttles back on the
charge current to maintain a junction temperature around the TJ(REG) threshold. To avoid false termination, the
termination detect function is disabled while in this mode.
The bq2407x also monitors the junction temperature, TJ, of the die and disconnects the OUT pin from the IN
input if TJ exceeds T(SHTDWN). This operation continues until TJ falls below T(SHTDWN) by the hysteresis level
specified in the specification table.
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The battery supplement mode has no thermal protection. The Q2 FET continues to connect the battery to the
output (system), if input power is not sufficient; however, a short-circuit protection circuit limits the battery
discharge current such that the maximum power dissipation of the part is not exceeded under typical design
conditions.
8.4.3.7 Charge Timer Operation
As a safety backup, the bq2407x monitors the charge time in the charge mode. If the termination threshold is not
detected within the time period, t(CHG), the bq2407x turns off the charger and enunciates FAULT on the STAT1
and STAT2 pins. The resistor connected between the TMR and VSS, RTMR, determines the timer period. The
K(TMR) parameter is specified in the specifications table. In order to disable the charge timer, eliminate RTMR,
connect the TMR pin directly to the VREF pin. Note that this action eliminates the fast-charge safety timer (it does
not disable or reset the precharge safety timer), and also clears any timer fault. TMR pin should not be left
floating.
t (CHG) = K(TMR) × R(TMR)
(5)
While in the thermal regulation mode or DPPM mode, the bq2407x dynamically adjusts the timer period in order
to provide the additional time needed to fully charge the battery. This proprietary feature is designed to prevent
against early or false termination. The maximum charge time in this mode, t(CHG-TREG), is calculated by
Equation 6.
t (CHG) × V(SET)
t (CHG−TREG) =
V (SET – REG)
(6)
Note that because this adjustment is dynamic and changes as the ambient temperature changes and the charge
level changes, the timer clock is adjusted. It is difficult to estimate a total safety time without integrating the
above equation over the charge cycle. Therefore, understanding the theory that the safety time is adjusted
inversely proportionately with the charge current and the battery is a current-hour rating, the safety time
dynamically adjusts appropriately.
The V(SET) parameter is specified in the specifications table. V(SET-TREG) is the voltage on the ISET pin during the
thermal regulation or DPPM mode and is a function of charge current. (Note that charge current is dynamically
adjusted during the thermal regulation or DPPM mode.)
I (OUT) × R(SET)
V (SET−TREG) =
K(SET)
(7)
All deglitch times also adjusted proportionally to t(CHG-TREG).
8.4.3.8 Timer Fault Recovery
As shown in Figure 6, bq2407x provides a recovery method to deal with timer fault conditions. The following
summarizes this method:
Condition 1: Charge voltage above recharge threshold (V(RCH)) and time-out fault occurs.
Recovery Method: bq2407x waits for the battery voltage to fall below the recharge threshold. This could happen
as a result of a load on the battery, self-discharge, or battery removal. Once the battery falls below the recharge
threshold, the bq2407x clears the fault and starts a new charge cycle. A POR or CE toggle also clears the fault.
Condition 2: Charge voltage below recharge threshold (V(RCH)) and time-out fault occurs.
Recovery Method: Under this scenario, the bq2407x applies the I(FAULT) current. This small current is used to
detect a battery removal condition and remains on as long as the battery voltage stays below the recharge
threshold. If the battery voltage goes above the recharge threshold, then the bq2407x disables the I(FAULT) current
and executes the recovery method described for condition 1. Once the battery falls below the recharge threshold,
the bq2407x clears the fault and starts a new charge cycle. A POR or CE toggle also clears the fault.
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8.4.3.9 Charge Termination and Recharge
The bq2407x monitors the voltage on the ISET1 pin, during voltage regulation, to determine when termination
should occur. Termination occurs when the charge current tapers down to either 1/10th of the programmed fast
charge rate (when the MODE pin is high) or 1/25th of the programmed fast charge rate (when the MODE pin is
low). Once the termination threshold, I(TERM), is detected the bq2407x terminates charge. The RSET resistor,
connected between the ISET1 and VSS pins, programs the fast charge current level and thus the current
termination threshold level. The V(TERM) and K(SET) parameters are specified in the specifications table. Note that
this applies to both IN and USB charging.
V(TERM) × K(SET)
I (TERM) =
R SET
(8)
After charge termination, the bq2407x re-starts the charge once the voltage on the BAT pin falls below the V(RCH)
threshold. This feature keeps the battery at full capacity at all times.
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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
Compared to chargers without dynamic power path management (DPPM), this single-cell LiIon battery charger
provides instant system power even with a deeply discharged battery. The maximum charge current is set by
ISET2 but the input current limit circuitry, controlled by ISET1 and MODE pins or the DPPM circuitry can reduce
the charge current from the maximum desired value.
9.2 Typical Application
Figure 7. Typical Application Circuit
9.2.1 Design Requirements
A bq24070 (VOUT = 4.4 Vreg) is powered through an AC adaptor with IN input is set for approximately 5.1 V (1.5 A
current limit), I(CHG) = 1 A, V(DPPM-SET) = 3.7 V, V(DPPM-REG) = 1.15 × V(DPPM-SET) = 4.26 V, Mode = H, and USB
input is not connected. A 103AT thermistor is inside the battery pack. A 6-hour saftey time-out is desired.
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Typical Application (continued)
9.2.2 Detailed Design Procedure
The minimum required 0.1 μF capacitors are placed on IN and OUT. Additional 10-μF capacitors are included on
IN and OUT to improve load transient response. The recommended (but not required) 33-μF capacitor on BAT is
added to allow for operation when no battery is attached. A 0.22-μF capacitor is connected between BAT and
ISET1 to improve operation at low charge currents.
Rearranging Equation 4 gives RSET = V(SET) x K(SET) / IO(BAT) = 2.5 V x 425 / 1 A = 1062.5 Ω → 1070 Ω. Per
Equation 3, the precharge current is 100 mA and per Equation 8, the termination current is 100 mA. Since MODE
is high, in order to prevent the charge current from being reduced by 1/2, ISET2 is tied high.
Rearranging Equation 5 gives RTMR = t(CHG) / K(TMR) gives 6 hrs x 60 min/hr x 60 s/min / 0.360 s/Ω = 60 kΩ →
60.4 kΩ
Rearranging Equation 1 gives RDPPM = V(DPPM-REG) / (I(DPPM) x SF) = 4.26 V / ( 100 μA x 1.15) = 37.044 kΩ →37.4
kΩ. CDPPM of 10 nF was added to prevent the IC from falsely entering short circuit protection at start-up.
Not shown are 1.5-kΩ resistors and LEDs pulled up to V(IN) from STAT1, STAT2, and PG.
9.2.2.1 Selecting the Input and Output Capacitors
In most applications, all that is needed is a high-frequency decoupling capacitor on the input. A 0.1-μF ceramic
capacitor placed in close proximity to the IN to VSS pins works well. In some applications, depending on the
power-supply characteristics and cable length, adding an additional 4.7-μF to 10-μF ceramic capacitor to the
input might be required.
The bq2407x requires only a small output capacitor for loop stability. A 0.1-μF ceramic capacitor placed between
the OUT and VSS pin is typically sufficient. TI recommends installing at least an additional 10-uF ceramic
capacitor between OUT and VSS in order to improve load transient response.
TI recommends installing a minimum 33-μF capacitor between the BAT pin and VSS (in parallel with the battery).
This configuration ensures proper hot-plug power up with a no-load condition (no system load or battery
attached).
VREF output capacitor with a value of 0.1 μF is required. A 0.22-μF capacitor connected between BAT and ISET1
is recommended to improve operation at low charge currents.
This short-circuit disable feature was implemented mainly for power up when inserting a battery. Because the
BAT input voltage rises much faster than the OUT voltage (Vout
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