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bq21040
SLUSCE2D – APRIL 2016 – REVISED JANUARY 2019
bq21040 0.8-A, Single-Input, Single Cell Li-Ion and Li-Pol Battery Charger
1 Features
3 Description
•
The bq21040 device is a highly integrated Li-Ion and
Li-Pol linear battery charger device targeted at spacelimited portable applications. The device operates
from either a USB port or AC adapter. The high input
voltage range with input overvoltage protection
supports low-cost unregulated adapters.
1
•
•
Charging
– 1% Charge Voltage Accuracy
– 10% Charge Current Accuracy
– Low Battery Leakage Current (1 µA)
– Programmable Charge Current using External
Resistor up to 800 mA
– 4.2-V Li-Ion and Li-Pol Charger
Protection
– 30-V Input Rating; with 6.6-V Input
Overvoltage Protection
– Input Voltage Dynamic Power Management
– 125°C Thermal Regulation; 150°C Thermal
Shutdown Protection
– OUT Short-Circuit Protection and ISET Short
Detection
– Overtemperature Sensing Protection Through
NTC
– Fixed 10-Hour Safety Timer
System
– Status Indication – Charging/Done
– Available in Small SOT-23 Package
The battery is charged in three phases: conditioning,
constant current and constant voltage. In all charge
phases, an internal control loop monitors the IC
junction temperature and reduces the charge current
if an internal temperature threshold is exceeded.
The charger power stage and charge current sense
functions are fully integrated. The charger function
has high accuracy current and voltage regulation
loops, charge status display, and charge termination.
The pre-charge current and termination current
threshold are fixed to 20% and 10%, respectively.
The fast charge current value is programmable
through an external resistor.
Device Information(1)
2 Applications
•
•
•
•
The bq21040 has a single power output that charges
the battery. A system load can be placed in parallel
with the battery as long as the average system load
does not keep the battery from charging fully during
the 10 hour safety timer.
PART NUMBER
EPOS
Medical Endoscopes
BLE Speaker and Headsets
Low-Power Handheld Devices
bq21040
PACKAGE
SOT-23 (6)
BODY SIZE (NOM)
3.00 mm × 1.75 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Simplified Schematic
bq21040
VIN
VIN
VOUT
BAT
TEMP
1 µF
ISET
TS
RISET
PACK+
1 µF
NTC
+
±
System
Load
RCHG
PACK±
GND
CHG
Copyright © 2016, Texas Instruments Incorporated
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.
bq21040
SLUSCE2D – APRIL 2016 – REVISED JANUARY 2019
www.ti.com
Table of Contents
1
2
3
4
5
6
7
8
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Device Comparison ...............................................
Pin Configuration and Functions .........................
Specifications.........................................................
1
1
1
2
3
3
3
7.1
7.2
7.3
7.4
7.5
7.6
7.7
3
4
4
4
4
6
Absolute Maximum Ratings ......................................
ESD Ratings ............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Timing Requirements ................................................
Typical Operational Characteristics (Protection
Circuits Waveforms)...................................................
7
Detailed Description .............................................. 8
8.1 Overview ................................................................... 8
8.2 Functional Block Diagram ......................................... 9
8.3 Feature Description................................................. 10
8.4 Device Functional Modes........................................ 13
9
Application and Implementation ........................ 17
9.1 Application Information............................................ 17
9.2 Typical Application .................................................. 17
10 Power Supply Recommendations ..................... 22
11 Layout................................................................... 22
11.1 Layout Guidelines ................................................. 22
11.2 Layout Example .................................................... 22
11.3 Thermal Considerations ........................................ 23
12 Device and Documentation Support ................. 24
12.1
12.2
12.3
12.4
12.5
Receiving Notification of Documentation Updates
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
24
24
24
24
24
13 Mechanical, Packaging, and Orderable
Information ........................................................... 24
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision C (August 2017) to Revision D
Page
•
Changed HBM From: ±1000 To: ±2000 in the ESD Ratings.................................................................................................. 4
•
Changed CDM From: ±250 To: ±500 in the ESD Ratings ..................................................................................................... 4
Changes from Revision B (May 2017) to Revision C
Page
•
Changed Simplified Schematic .............................................................................................................................................. 1
•
Changed 250 kΩ to 237 kΩ in TS pin description.................................................................................................................. 3
•
Changed RTS max from 25.8 kΩ to 258 kΩ ............................................................................................................................ 4
•
Changed Low temperature charging to Normal temperature charging in VTS-0C Test Conditions .......................................... 6
•
Changed low temperature charging to normal temperature charging in VHYS-0C Test Conditions ......................................... 6
•
Changed High temperature charging to Normal temperature charging in VTS-45C Test Conditions ....................................... 6
•
Changed high temperature charging to normal temperature charging in VHYS-45C Test Conditions ...................................... 6
•
Deleted Load Regulation graph ............................................................................................................................................. 7
•
Deleted Line Regulation graph .............................................................................................................................................. 7
•
Changed Figure 6 ................................................................................................................................................................ 11
•
Deleted The bq21040 does not have a safety timer. in Timers ........................................................................................... 15
•
Changed Figure 10 .............................................................................................................................................................. 17
Changes from Revision A (April 2016) to Revision B
Page
•
Changed MIN and MAX values in the Electrical Characteristics table, Changed MIN and MAX values for Fast
charge current factor, KISET ................................................................................................................................................. 1
•
Added Receiving Notification of Documentation Updates section ........................................................................................ 1
2
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5
SLUSCE2D – APRIL 2016 – REVISED JANUARY 2019
Device Comparison
PART NO.
VO(REG)
VOVP
TS
PACKAGE
bq21040
4.20 V
6.6 V
TS
3.00 mm × 1.75 mm × 1.45 mm SOT-23
6 Pin Configuration and Functions
DBV Package
6-Pin SOT-23
Top View
TS
1
6
VIN
OUT
2
5
GND
CHG
3
4
ISET
Pin Functions
PIN
NAME
NO.
I/O
DESCRIPTION
CHG
3
O
Low (FET on) indicates charging and Open Drain (FET off) indicates no Charging or Charge
complete.
GND
5
—
Ground terminal
ISET
4
I
Programs the Fast-charge current setting. External resistor from ISET to VSS defines fast charge
current value. Range is 10.8kΩ (50mA) to 675Ω (800mA).
OUT
2
O
Battery connection. System load may be connected. Expected range of bypass capacitors 1μF to
10μF.
TS
1
I
Temperature sense terminal connected to bq21040 -10k at 25°C NTC thermistor, in the battery
pack. Floating T terminal or pulling High puts part in TTDM “Charger” Mode and disable TS
monitoring, Timers and Termination. Pulling terminal Low disables the IC. If NTC sensing is not
needed, connect this terminal to VSS through an external 10 kΩ resistor. A 237 kΩ from TS to
ground will prevent IC entering TTDM mode when battery with thermistor is removed.
VIN
6
I
Input power, connected to external DC supply (AC adapter or USB port). Expected range of
bypass capacitors 1μF to 10μF, connect from IN to VSS.
7 Specifications
7.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) (1)
Input voltage
(2)
MIN
MAX
UNIT
IN (with respect to VSS)
–0.3
30
V
OUT (with respect to VSS)
–0.3
7
V
PRE-TERM, ISET, ISET2, TS, /CHG (with respect to VSS)
–0.3
7
V
A
Input current
IN
1.25
Output current (continuous)
OUT
1.25
A
Output sink current
CHG
15
mA
Junction temperature, TJ
–40
150
°C
Storage temperature, Tstg
–65
150
°C
(1)
(2)
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
All voltage values are with respect to the network ground terminal unless otherwise noted.
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SLUSCE2D – APRIL 2016 – REVISED JANUARY 2019
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7.2 ESD Ratings
VALUE
V(ESD)
(1)
(2)
Electrostatic discharge
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1)
±2000
Charged-device model (CDM), per JEDEC specification JESD22C101 (2)
±500
UNIT
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.
7.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
MIN
IN voltage range
VIN
IN operating voltage range, restricted by VDPM and VOVP
IIN
Input current, IN terminal
IOUT
Current, OUT terminal
TJ
Junction temperature
RISET
Fast-charge current programming resistor
RTS
10k NTC thermistor range without entering TTDM
NOM
MAX
UNIT
3.5
28
V
4.45
6.45
V
0.8
A
0.8
A
0
125
°C
0.675
10.8
kΩ
1.66
258
kΩ
7.4 Thermal Information
bq21040
THERMAL METRIC (1)
DBV (SOT-23)
UNIT
6 PINS
RθJA
Junction-to-ambient thermal resistance
130.8
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
75.2
°C/W
RθJB
Junction-to-board thermal resistance
45.5
°C/W
ψJT
Junction-to-top characterization parameter
31.8
°C/W
ψJB
Junction-to-board characterization parameter
45.5
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
n/a
°C/W
(1)
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report.
7.5 Electrical Characteristics
over operating free-air temperature range (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
INPUT
UVLO
Undervoltage lockout exit
VIN: 0 V to 4 V
3.15
3.3
3.45
V
VHYS-UVLO
Hysteresis on VUVLO_RISE falling
VIN: 0 V to 4 V, VUVLO_FALL =
VUVLO_RISE – VHYS-UVLO
175
227
280
mV
VIN-DT
Input power good detection
threshold is VOUT+VIN-DT
(Input power good if VIN > VOUT + VINDT); VOUT = 3.6 V, VIN: 3.5 V to 4 V
30
80
145
mV
VHYS-INDT
Hysteresis on VIN-DT falling
VOUT = 3.6 V, VIN: 4 V to 3.5 V
VOVP
Input overvoltage protection
threshold
VIN: 5 V to 12 V
VHYS-OVP
Hysteresis on OVP
VIN: 11 V to 5 V
VIN-DPM
Adaptor low input voltage
protection. Restricts lout at VINDPM
Feature active in adaptor mode; Limit
Input Current to 50 mA; VOUT = 3.5 V;
RISET = 825
31
6.5
6.65
mV
6.8
95
4.24
4.3
V
mV
4.46
V
500
Ω
ISET SHORT CIRCUIT TEST
RISET_SHORT
4
Highest resistance considered a
fault (short). Monitored for
IOUT>90mA
RISET: 250 Ω to 540 Ω, Iout latches off.
Cycle power to reset
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Electrical Characteristics (continued)
over operating free-air temperature range (unless otherwise noted)
PARAMETER
IOUT_CL
Maximum OUT current limit
regulation (clamp)
TEST CONDITIONS
MIN
VIN = 5 V, VOUT = 3.6 V, RISET: 250 Ω to
540 Ω, Iout latches off after tDGL-SHORT
1.05
0.75
TYP
MAX
UNIT
1.4
A
0.85
V
BATTERY SHORT PROTECTION
VOUT(SC)
OUT terminal short-circuit detection
threshold/precharge threshold
Vout:3V to 0.5V, no deglitch
VOUT(SC-HYS)
OUT terminal short hysteresis
Recovery ≥ VOUT(SC) + VOUT(SC-HYS);
Rising, no deglitch
IOUT(SC)
Source current to OUT terminal
during short-circuit detection
0.8
77
10
15
mV
20
mA
QUIESCENT CURRENT
IOUT(PDWN)
Battery current into OUT terminal
VIN = 0V
1
µA
IOUT(DONE)
OUT pin current, charging
terminated
VIN = 6 V, VBAT > VBAT(REG), net current
is into OUT pin
6
µA
IIN(STDBY)
Standby current into IN pin
TS = Low, VIN ≤ 6 V
125
µA
ICC
Active supply current, IN pin
TS = Low, VIN = 6 V, no load on OUT
pin, VBAT > VBAT(REG)
1000
µA
4.23
V
800
mA
325
550
mV
KISET/
RISET
KISET/
RISET
KISET/
RISET
KISET (60mA < I VOUT > VLOWV; VIN = 5 V,
RISET = 0.675 to 52 kΩ
10
VDO(IN-OUT)
Drop-Out, VIN – VOUT
Adjust VIN down until IOUT = 0.5 A, VOUT
= 4.15 V, RISET = 1.08kΩ
IOUT
Output fast charge formula
VOUT(REG) > VOUT > VLOWV; VIN = 5 V
KISET
Fast charge current factor
4.2
A
AΩ
PRECHARGE
VLOWV
Pre-charge to fast-charge transition
threshold
Pre-charge
Default pre-charge current
VBAT < VLOWV, ICHG = 50 mA
Termination Threshold Current,
default setting
VOUT > VRCH; RISET = 1 kΩ
TERMINATION
%TERM
RECHARGE OR REFRESH
VRCH
Recharge detection threshold
VIN = 5 V, VTS = 0.5 V, VOUT = 4.25 V to
VRCH
VO(REG) - VO(REG) - VO(REG) 120 mV
95 mV
70 mV
mV
VIN = 5 V, VTS = 0.5 V, battery absent
VO(REG) - VO(REG) - VO(REG) 450 mV
400 mV
350 mV
mV
BATT DETECT
VREG-BD
VOUT Reduced regulation during
battery detect
IBD-SINK
Sink current during VREG-BD
VBD-HI
7
High battery detection threshold
VIN = 5 V, VTS = 0.5 V, battery absent
VBD-LO
Low battery detection threshold
10
mA
VO(REG) - VO(REG) - VO(REG) 150 mV
100 mV
50 mV
V
VREGBD+0.50
VREGBD+0.1
VREGBD+0.15
V
48
50
53
µA
27
30
34
µA
4
5
6.5
µA
BATTERY-PACK NTC MONITOR
INTC 50µA
NTC bias current
INTC-DIS-10K
10K NTC bias current when
charging is disabled
VTS = 0 V
INTC-FLDBK -10K
INTC is reduced prior to entering
TTDM to keep cold thermistor from
entering TTDM
VTS = 1.525 V
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Electrical Characteristics (continued)
over operating free-air temperature range (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
1550
1600
1650
mV
1800
1950
VTTDM(TS)
Termination and timer disable
mode-Threshold-Enter
VTS: 0.5 V to 1.7 V; timer held in reset
IHYS-TTDM(TS)
Hysteresis exiting TTDM
VTS: 1.7 V to 0.5 V; timer enabled
VCLAMP(TS)
TS maximum voltage clamp
VTS = Open (float)
VTS_I-FLDBK
TS voltage where INTC is reduce to INTC adjustment (90 to 10%; 45 to 6.6
keep thermistor from entering
µs) takes place near this spec
TTDM
threshold. VTS: 1.425 V to 1.525 V
1475
mV
CTS
Optional capacitance – ESD
0.22
µF
100
VTS-0C
Low temperature CHG pending
Normal temperature charging to
pending; VTS: 1 V to 1.5 V
VHYS-0C
Hysteresis at 0°C
Charge pending to normal temperature
charging; VTS: 1.5 V to 1 V
VTS-45C
High temperature CHG disable
Normal temperature charging to
pending; VTS: 0.5 V to 0.2 V
VHYS-45C
Hysteresis at 45°C
Charge pending to normal temperature
charging; VTS: 0.2 V to 0.5 V
VTS-EN-10K
Charge enable threshold (10k NTC) VTS: 0 V to 0.175 V
VTS-DIS_HYS-10K
HYS below VTS-EN-10k to disable
(10k NTC)
1220
mV
2000
1250
1280
100
260
290
20
mV
mV
88
VTS: 0.125 V to 0 V
mV
mV
275
80
mV
96
12
mV
mV
THERMAL REGULATION
TJ(REG)
Temperature regulation limit
125
TJ(OFF)
Thermal shutdown temperature
155
TJ(OFF-HYS)
Thermal shutdown hysteresis
°C
20
CHG INDICATION
VOL
Output Low Voltage-CHG FET on first charge after power-up
ISINK = 5 mA
0.4
V
ILEAK
Leakage current into IC
V CHG = 5 V
1
µA
7.6 Timing Requirements
MIN
NOM
MAX
UNIT
INPUT
tDGL(OVP_SET)
Input over-voltage blanking time
VIN: 5 V to 12 V
tDGL(OVP_REC)
Deglitch time exiting OVP
Time measured from VIN: 12V to 5V
113
µs
30
µs
1
ms
ISET SHORT CIRCUIT TEST
tDGL_SHORT
Deglitch time transition from ISET short Clear fault by disconnecting IN or cycling
to IOUT disable
(high / low) TS
PRECHARGE – SET INTERNALLY
tDGL1(LOWV)
Deglitch time on pre-charge to fastcharge transition
70
µs
tDGL2(LOWV)
Deglitch time on fast-charge to precharge transition
32
ms
Deglitch time, termination detected
29
ms
29
ms
25
ms
30
ms
TERMINATION
tDGL(TERM)
RECHARGE OR REFRESH
tDGL1(RCHG)
Deglitch time, recharge threshold
detected
VIN = 5 V, VTS = 0.5 V, VOUT: 4.25 V to 3.5
V in 1 µs; tDGL(RCHG) is time to ISET ramp
BATTERY DETECT ROUTINE
tDGL(HI/LOW REG)
Regulation time at VREG or VREG-BD
BATTERY-PACK NTC MONITOR; TS TERMINAL
tDGL(TS)
6
Deglitch for TS thresholds: 0/45C.
Battery charging
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7.7 Typical Operational Characteristics (Protection Circuits Waveforms)
SETUP: bq21040 typical applications schematic; VIN = 5V, VBAT = 3.6V (unless otherwise indicated)
4.212
546
VO at 0°C
Kiset
VOUT - Output Voltage DC - V
542
Low to High Currents
(may occur in recharge to fast charge transion)
540
Kiset - W
ROUT = 100 Ω
4.21
544
538
High to Low Currents
(may occur in Voltage Regulation - Taper Current)
536
534
532
4.208
4.206
VO at 25°C
4.204
VO at 85°C
4.202
4.2
4.198
530
4.196
4.5
528
0
.15
0.2
0.4
IO - Output Current - A
0.6
0.8
5
6
6.5
Figure 2. Line Regulation
Figure 1. Kiset for Low and High Currents
363.4
4.2
363.2
4.199
IO at 25°C
IO - Output Current - mA
Vreg at 25°C
VOUT - Output Voltage - V
5.5
VI - Input Voltage DC - V
4.198
Vreg at 85°C
4.197
4.196
4.195
Vreg at 0°C
363
362.8
362.4
4.194
362.2
4.193
362
4.192
0
0.2
0.4
0.6
IO - Output current - A
0.8
1
IO at 85°C
362.6
IO at 0°C
361.8
2.5
3
3.5
VO - Output Voltage - V
4
4.5
Figure 4. Current Regulation Over Temperature
Figure 3. Load Regulation Over Temperature
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8 Detailed Description
8.1 Overview
The bq21040 is a highly integrated single cell Li-Ion and Li-Pol charger. The charger can be used to charge a
battery, power a system or both. The charger has three phases of charging: Pre-charge to recover a fully
discharged battery, fast-charge constant current to supply the buck charge safely and voltage regulation to safely
reach full capacity. The charger is very flexible, allowing programming of the fast-charge current. This charger is
designed to work with a USB connection or Adaptor (DC out). The charger also checks to see if a battery is
present.
The charger also comes with a full set of safety features: Temperature Sensing Standard, Over-Voltage
Protection, DPM-IN, Safety Timers, and ISET short protection. All of these features and more are described in
detail below.
The charger is designed for a single power path from the input to the output to charge a single cell Li-Ion or
Li-Pol battery pack. Upon application of a 5VDC power source the ISET and OUT short checks are performed to
assure a proper charge cycle.
If the battery voltage is below the LOWV threshold, the battery is considered discharged and a preconditioning
cycle begins. The amount of the current goes into the battery during this phase is called pre-charge current. It is
fixed to 20% of the fast charge current.
Once the battery voltage has charged to the VLOWV threshold, fast charge is initiated and the fast charge
current is applied. The fast charge constant current is programmed using the ISET terminal. The constant current
provides the bulk of the charge. Power dissipation in the IC is greatest in fast charge with a lower battery voltage.
If the IC reaches 125°C the IC enters thermal regulation, slows the timer clock by half and reduce the charge
current as needed to keep the temperature from rising any further. Figure 5 shows the charging profile with
thermal regulation. Typically under normal operating conditions, the IC’s junction temperature is less than 125°C
and thermal regulation is not entered.
Once the cell has charged to the regulation voltage the voltage loop takes control and holds the battery at the
regulation voltage until the current tapers to the termination threshold. The termination current is set to 10% of
the fast charge current. The CHG terminal is low (LED on) during the first charge cycle only and turns off once
the termination threshold is reached, regardless if termination, for charge current, is enabled or disabled.
8
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8.2 Functional Block Diagram
Internal Charge Current Sense
w/Multiple Outputs
IN
OUT
80 mV
+
Input
Power
Detect
IN
OUT
-
+
-
+
OUT
IN,DPM
+
-
-
Charge
Pump
TjC
-
Fast Charge
Pre-Charge
ISET
+
IOUT x 1.5V
540 AŸ
VO,REG
IN
125 CREF
+
1.5V
-
Pre-CHG Reference
75uA
Term Reference
TjC
+
_
150 CREF
+
_
Charge
Pump
Thermal Shutdown
+
IN
X2 Gain (1:2)
Term: Pre-CHGX2
+
_
_
OVPREF
CHG
On During 1st
Charge Only
+
_
TS_0C
+
_
VREF_0C_COLD
TS_45C
ON
OFF:
CHARGE
CONTROL
VTTDM
TTDM MODE
TS Cold Temperature
Sink Current
45uA
5uA
+
_
VCLAMP
TS Disable
Sink Current
20uA
_
+
_
TS
+
VREF_45C_HOT
45uA
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8.3 Feature Description
VO(REG)
PreConditioning
Phase
Thermal
Regulation
Phase
Current
Regulation
Phase
Voltage Regulation and
Charge Termination
Phase
DONE
IO(OUT)
FAST-CHARGE
CURRENT
PRE-CHARGE
CURRENT AND
TERMINATION
THRESHOLD
Battery Current,
I(OUT)
Battery
Voltage,
V(OUT)
Charge
Complete
Status,
Charger
Off
VO(LOWV)
I(TERM)
IO(PRECHG)
T(THREG)
0A
Temperature, Tj
T(CHG)
T(PRECHG)
DONE
Figure 5. Charging Profile With Thermal Regulation
8.3.1 Power-Down or Undervoltage Lockout (UVLO)
The bq21040 is in power-down mode if the IN terminal voltage is less than UVLO. The part is considered “dead”
and all the terminals are high impedance. Once the IN voltage rises above the UVLO threshold the IC will enter
Sleep Mode or Active mode depending on the OUT terminal (battery) voltage.
8.3.2 Power-up
The IC is alive after the IN voltage ramps above UVLO (see sleep mode), resets all logic and timers, and starts
to perform many of the continuous monitoring routines. Typically the input voltage quickly rises through the
UVLO and sleep states where the IC declares power good, starts the qualification charge at 100mA starts the
safety timer and enables the CHG terminal. See Figure 6.
8.3.3 Sleep Mode
If the IN terminal voltage is between than VOUT+VDT and UVLO, the charge current is disabled, the safety timer
counting stops (not reset) and the CHG terminal is high impedance. As the input voltage rises and the charger
exits sleep mode, the safety timer continues to count, charge is enabled and the CHG terminal returns to its
previous state. See Figure 7.
8.3.4 New Charge Cycle
A new charge cycle is started when a good power source is applied, performing a chip disable/enable (TS
terminal), exiting Termination and Timer Disable Mode (TTDM), detecting a battery insertion or the OUT voltage
dropping below the VRCH threshold. The CHG terminal is active low only during the first charge cycle, therefore
exiting TTDM or a dropping below VRCH will not turn on the CHG terminal FET, if the CHG terminal is already
high impedance.
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VTS
1.8V
Normal
Operation
Disabled
HOT
Fault
Disabled
Cold
Fault
Normal
Operation
TTDM
Mode
Cold
Fault
Normal
Operation
tDGL(TTDM)
Enter
Normal
Operation
TTDM
Mode
tDGL(TTDM)
Enter
tDGL(TTDM)
Exit
TTDM
t < tDGL(TTDM)
Exit
TTDMHYS
tDGL(TS)
tDGL(TS)
tDGL(TS)
0°C
0°CHYS
tDGL(TS)
tDGL(TS)
tDGL(TS)
45°CHYS
45°C
Dots Show Threshold Trip Points
followed by a deglitch time before
transitioning into a new mode.
EN
DISHYS
0V
Drawing Not to Scale
t
Figure 6. TS Battery Temperature Bias Threshold and Deglitch Timers
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Apply Input
Power
Is power good?
VBAT + VDT < VOVP &
VUVLO < VIN
No
Yes
Is chip enabled?
VTS > VEN
No
Yes
Set the Current Limit to 100 mA
and Start Charge Perform ISET &
OUT short tests
Yes
Set the charge current based on
ISET
Yes
Return to Charge
Figure 7. bq21040 Power-Up Flow Diagram
8.3.5 Overvoltage-Protection (OVP) – Continuously Monitored
If the input source applies an overvoltage, the pass FET, if previously on, turns off after a deglitch, tBLK(OVP). The
timer ends and the CHG terminal goes to a high impedance state. After the overvoltage returns to a normal
voltage, the timer continues, charge continues, and the CHG terminal goes low after a 25ms deglitch.
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CHG Terminal Indication
The charge terminal has an internal open drain FET which is on (pulls down to VSS) during the first charge only
(independent of TTDM) and is turned off once the battery reaches voltage regulation and the charge current
tapers to the termination threshold set by the PRE-TERM resistor. The bq21040 does not terminate charge,
however, the CHG terminal will turn off once the battery current reaches 10% of the programmed charge current.
The charge terminal is high impedance in sleep mode and OVP and returns to its previous state once the
condition is removed.
Cycling input power, pulling the TS terminal low and releasing or entering pre-charge mode causes the CHG
terminal to go reset (go low if power is good and a discharged battery is attached) and is considered the start of
a first charge.
8.4 Device Functional Modes
8.4.1
CHG LED Pull-up Source
For host monitoring, a pullup resistor is used between the STATUS terminal and the VCC of the host and for a
visual indication a resistor in series with an LED is connected between the STATUS terminal and a power
source. If the CHG source is capable of exceeding 7 V, a 6.2-V Zener should be used to clamp the voltage. If the
source is the OUT terminal, note that as the battery changes voltage, and the brightness of the LEDs vary.
Table 1. Charging States and CHG LED
CHARGING STATE
CHG FET/LED
First charge after VIN applied
ON
Refresh charge
OVP
OFF
SLEEP
TEMP FAULT
ON for 1st Charge
8.4.2 IN-DPM (VIN-DPM or IN-DPM)
The IN-DPM feature is used to detect an input source voltage that is folding back (voltage dropping), reaching its
current limit due to excessive load. When the input voltage drops to the VIN-DPM threshold the internal pass FET
starts to reduce the current until there is no further drop in voltage at the input. This would prevent a source with
voltage less than VIN-DPM to power the out terminal. This works well with current limited adaptors and USB ports
as long as the nominal voltage is above 4.3 V. This is an added safety feature that helps protect the source from
excessive loads.
8.4.3 OUT
The Charger’s OUT terminal provides current to the battery and to the system, if present. This IC can be used to
charge the battery plus power the system, charge just the battery or just power the system (TTDM) assuming the
loads do not exceed the available current. The OUT terminal is a current limited source and is inherently
protected against shorts. If the system load ever exceeds the output programmed current threshold, the output
will be discharged unless there is sufficient capacitance or a charged battery present to supplement the
excessive load.
8.4.4 ISET
An external resistor is used to Program the Output Current (50 to 800 mA) and can be used as a current monitor.
RISET = KISET / IOUT
where
•
•
IOUT is the desired fast charge current;
KISET is a gain factor found in the electrical specification
(1)
For greater accuracy at lower currents, part of the sense FET is disabled to give better resolution. Figure 1
shows the transition from low current to higher current. Going from higher currents to low currents, there is
hysteresis and the transition occurs around 0.15 A.
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1.8
1.6
IO - Output Current - A
1.4
IOUT Clamp min - max
IOUT Fault min - max
The ISET resistor is short protected and will detect a resistance lower than ≉340 Ω. The detection requires at
least 80mA of output current. If a “short” is detected, then the IC will latch off and can only be reset by cycling the
power. The OUT current is internally clamped to a maximum current between 1.05 A and 1.4 A and is
independent of the ISET short detection circuitry, as shown in Figure 8. Also, see Figure 23 and Figure 24.
1.2
IOUT Internal Clamp Range
1
0.8
IOUT Programmed
max
0.6
ISET Short
Fault
Range
min
0.4
0.2
Non Restricted
Operating Area
0
100
1000
10000
ISET - W
Figure 8. Programmed/Clamped Out Current
8.4.5 TS
The TS function is designed to follow the temperature sensing standard for Li-Ion and Li-Pol batteries. There are
two thresholds, 45°C and 0°C. Normal operation occurs between 0°C and 45°C.
The TS feature is implemented using an internal 50μA current source to bias the thermistor (designed for use
with a 10k NTC β = 3370 (SEMITEC 103AT-2 or Mitsubishi TH05-3H103F) connected from the TS terminal to
VSS. If this feature is not needed, a fixed 10kΩ can be placed between TS and VSS to allow normal operation.
This may be done if the host is monitoring the thermistor and then the host would determine when to pull the TS
terminal low to disable charge.
The TS terminal has two additional features, when the TS terminal is pulled low or floated/driven high. A low
disables charge (similar to a high on the BAT_EN feature) and a high puts the charger in TTDM.
Above 45°C or below 0°C the charge is disabled. Once the thermistor reaches ≉–10°C the TS current folds back
to keep a cold thermistor (between –10°C and –50°C) from placing the IC in the TTDM mode. If the TS terminal
is pulled low into disable mode, the current is reduce to ≉30μA, see Figure 6. Since the ITS curent is fixed along
with the temperature thresholds, it is not possible to use thermistor values other than the 10k NTC (at 25°C).
8.4.6 Termination and Timer Disable Mode (TTDM) - TS Terminal High
The battery charger is in TTDM when the TS terminal goes high from removing the thermistor (removing battery
pack/floating the TS terminal) or by pulling the TS terminal up to the TTDM threshold.
When entering TTDM, the 10 hour safety timer is held in reset and termination is disabled. A battery detect
routine is run to see if the battery was removed or not. If the battery was removed then the CHG terminal will go
to its high impedance state if not already there. If a battery is detected the CHG terminal does not change states
until the current tapers to the termination threshold, where the CHG terminal goes to its high impedance state if
not already there (the regulated output will remain on).
The charging profile does not change (still has pre-charge, fast-charge constant current and constant voltage
modes). This implies the battery is still charged safely and the current is allowed to taper to zero.
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When coming out of TTDM, the battery detect routine is run and if a battery is detected, then a new charge cycle
begins and the CHG LED turns on.
If TTDM is not desired upon removing the battery with the thermistor, one can add a 237k resistor between TS
and VSS to disable TTDM. This keeps the current source from driving the TS terminal into TTDM. This creates
≉0.1°C error at hot and a ≉3°C error at cold.
8.4.7 Timers
The pre-charge timer is set to 30 minutes. The pre-charge current, can be programmed to off-set any system
load, making sure that the 30 minutes is adequate.
The fast charge timer is fixed at 10 hours and can be increased real time by going into thermal regulation, INDPM or if in USB current limit. The timer clock slows by a factor of 2, resulting in a clock than counts half as fast
when in these modes. If either the 30 minute or ten hour timer times out, the charging is terminated and the CHG
terminal goes high impedance if not already in that state. The fast charge timer is reset by disabling the IC,
cycling power or going into and out of TTDM.
8.4.8 Termination
Once the OUT terminal goes above VRCH, (reaches voltage regulation) and the current tapers down to the
termination threshold (10% of the fast charge current), the CHG terminal goes high impedance and a battery
detect route is run to determine if the battery was removed or the battery is full. If the battery is present, the
charge current will terminate. If the battery was removed along with the thermistor, then the TS terminal is driven
high and the charge enters TTDM. If the battery was removed and the TS terminal is held in the active region,
then the battery detect routine will continue until a battery is inserted.
8.4.9 Battery Detect Routine
The battery detect routine should check for a missing battery while keeping the OUT terminal at a useable
voltage. Whenever the battery is missing the CHG terminal should be high impedance.
The battery detect routine is run when entering and exiting TTDM to verify if battery is present, or run all the time
if battery is missing and not in TTDM. On power-up, if battery voltage is greater than VRCH threshold, a battery
detect routine is run to determine if a battery is present.
The battery detect routine is disabled while the IC is in TTDM, or has a TS fault. See Figure 9 for the Battery
Detect Flow Diagram.
8.4.10 Refresh Threshold
After termination, if the OUT terminal voltage drops to VRCH (100mV below regulation) then a new charge is
initiated, but the CHG terminal remains at a high impedance (off).
8.4.11 Starting a Charge on a Full Battery
The termination threshold is raised by ≉14%, for the first minute of a charge cycle so if a full battery is removed
and reinserted or a new charge cycle is initiated, that the new charge terminates (less than 1 minute). Batteries
that have relaxed many hours may take several minutes to taper to the termination threshold and terminate
charge.
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Start
BATT_DETECT
Start 25ms timer
Timer Expired?
No
Yes
Is VOUTVREG-300mV?
Battery Present
Turn off Sink Current
Return to flow
No
Battery Absent
Don’t Signal Charge
Turn off Sink Current
Return to Flow
Figure 9. Battery Detect Routine (bq21040)
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9 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
9.1 Application Information
The bq21040 device is a highly integrated Li-Ion and Li-Pol linear charger device targeted at space-limited
portable applications. The device operates from either a USB port or AC adapter. The high input voltage range
with input overvoltage protection supports low-cost unregulated adapters. This device has a single power output
that charges the battery. A system load can be placed in parallel with the battery as long as the average system
load does not keep the battery from charging fully during the 10 hour safety timer.
9.2 Typical Application
IOUT_FAST_CHG = 540mA; IOUT_PRE_CHG = 108mA; IOUT_TERM = 54mA
bq21040
VIN
VIN
VOUT
BAT
TEMP
1 µF
ISET
TS
RISET
PACK+
1 µF
NTC
+
±
System
Load
RCHG
PACK±
GND
CHG
Copyright © 2016, Texas Instruments Incorporated
Figure 10. Typical Application Circuit
9.2.1 Design Requirements
• Supply voltage = 5 V
• Fast charge current: IOUT-FC = 540 mA; ISET-terminal 2
• Termination Current Threshold: %IOUT-FC = 10% of Fast Charge or about 54mA
• Pre-Charge Current by default is twice the termination Current or about 108mA
• TS – Battery Temperature Sense = 10k NTC (103AT)
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Typical Application (continued)
9.2.2 Detailed Design Procedure
9.2.2.1 Calculations
9.2.2.1.1 Program the Fast Charge Current, ISET:
RISET = [K(ISET) / I(OUT)]
(2)
From the Electrical Characteristics table:
• K(SET) = 540AΩ
• RISET = [540AΩ/0.54A] = 1.0 kΩ
Selecting the closest standard value, use a 1.0 kΩ resistor between ISET (terminal 16) and Vss.
9.2.2.1.2 Pre-Charge and Termination Current Thresholds, ITERM, and PRE-CHG
TERM = I(OUT) × 10%IOUT-FC
TERM = 540mA × 10% = 54mA
(3)
(4)
One can calculate the pre-charge current by using 20% of the fast charge current (factor of 2 difference).
PRE-Charge = I(OUT) × 20%IOUT-FC
PRE-Charge = 540mA × 20% = 108mA
(5)
(6)
9.2.2.1.3 TS Function
Use a 10k NTC thermistor in the battery pack (103AT).
To Disable the temp sense function, use a fixed 10k resistor between the TS (terminal 1) and Vss.
9.2.2.1.4
CHG
LED Status: connect a 1.5kΩ resistor in series with a LED between the OUT terminal and the CHG terminal.
Processor Monitoring: Connect a pull-up resistor between the processor’s power rail and the CHG terminal.
9.2.2.2 Selecting In and Out Terminal Capacitors
In most applications, all that is needed is a high-frequency decoupling capacitor (ceramic) on the power terminal,
input and output terminals. Using the values shown on the application diagram, is recommended. After
evaluation of these voltage signals with real system operational conditions, one can determine if capacitance
values can be adjusted toward the minimum recommended values (DC load application) or higher values for fast
high amplitude pulsed load applications. Note if designed for high input voltage sources (bad adaptors or wrong
adaptors), the capacitor needs to be rated appropriately. Ceramic capacitors are tested to 2x their rated values
so a 16V capacitor may be adequate for a 30V transient (verify tested rating with capacitor manufacturer).
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Typical Application (continued)
9.2.3 Application Curves
SETUP: bq21040 typical applications schematic; VIN = 5V, VBAT = 3.6V (unless otherwise indicated)
Figure 11. Power-Up Timing
Figure 12. Power-Up Timing – No Battery or Load in TTDM
Figure 13. Start-Up in Thermal Regulation
Figure 14. TS Entering and Leaving Cold Temperature
Figure 15. OVP 8-V Adaptor — Hot Plug
Figure 16. OVP From Normal Power-Up
Operation – VIN 0 V → 6 V → 7 V → 6 V→ 0 V
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Typical Application (continued)
.
Fixed 10kΩ resistor, between TS and GND.
Figure 18. Power-Up Timing with No Battery and No
Load – Battery Detection
Figure 17. TS Enable and Disable
Figure 20. Battery Removal With OUT and
TS Disconnect 1st, With 100-Ω Load
Figure 19. Battery Removal – GND Removed 1st, 42-Ω
Load
Continuous battery detection when not in TTDM
CH4: IOUT (1A/Div)
Battery voltage swept from 0V to 4.25V to 3.9V.
Figure 21. Battery Removal With Fixed TS = 0.5 V
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Figure 22. Battery Charge Profile
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Typical Application (continued)
CH4: IOUT (1A/Div)
CH4: IOUT (0.2A/Div)
Figure 23. ISET Shorted During Normal Operation
Figure 24. ISET Shorted Prior to USB Power-up
CH4: IOUT (0.2A/Div)
Figure 25. DPM – Adaptor Current Limits – VIN Regulated
The IC temperature rises to 125°C and enters thermal
regulation. Charge current is reduced to regulate the IC at
125°C. VIN is reduced, the IC temperature drops, the charge
current returns to the programmed value
Figure 26. DPM – USB Current Limits – VIN Regulated to
4.4 V
VIN swept from 5 V to 3.9 V to 5 V
VBAT = 4 V
.
Figure 27. Charge Cycle With Thermal Regulation
Figure 28. Entering and Exiting UVLO
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10 Power Supply Recommendations
The devices are designed to operate from an input voltage supply range between 3.5 V and 28 V and current
capability of at least the maximum designed charge current. This input supply should be well regulated. If located
more than a few inches from the bq21040 IN and GND terminals, a larger capacitor is recommended.
11 Layout
11.1 Layout Guidelines
To obtain optimal performance, the decoupling capacitor from IN to GND (thermal pad) and the output filter
capacitors from OUT to GND (thermal pad) should be placed as close as possible to the bq21040, with short
trace runs to both IN, OUT, and GND (thermal pad).
• All low-current GND connections should be kept separate from the high-current charge or discharge paths
from the battery. Use a single-point ground technique incorporating both the small signal ground path and the
power ground path.
• The high current charge paths into IN terminal and from the OUT terminal must be sized appropriately for the
maximum charge current in order to avoid voltage drops in these traces
• The bq21040 is packaged in a thermally-enhanced MLP package. The package includes a thermal pad to
provide an effective thermal contact between the IC and the printed circuit board (PCB); this thermal pad is
also the main ground connection for the device. Connect the thermal pad to the PCB ground connection. It is
best to use multiple 10mil vias in the power pad of the IC and close enough to conduct the heat to the bottom
ground plane. The bottom ground place should avoid traces that “cut off” the thermal path. The thinner the
PCB the less temperature rise. The EVM PCB has a thickness of 0.031 inches and uses 2 oz. (2.8mil thick)
copper on top and bottom, and is a good example of optimal thermal performance.
11.2 Layout Example
Figure 29. Board Layout
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11.3 Thermal Considerations
The bq21040 is packaged in a thermally-enhanced MLP package. The package includes a thermal pad to
provide an effective thermal contact between the IC and the printed circuit board (PCB). The power pad should
be directly connected to the VSS terminal. The most common measure of package thermal performance is
thermal impedance (RθJA) measured (or modeled) from the chip junction to the air surrounding the package
surface (ambient). The mathematical expression for ψJT is:
ψJT = (TJ – T) / P
where
•
•
•
TJ = Chip junction temperature
P = Device power dissipation
T = Case temperature
(7)
Factors that can influence the measurement and calculation of ψJT include:
1. Whether or not the device is board mounted
2. Trace size, composition, thickness, and geometry
3. Orientation of the device (horizontal or vertical)
4. Volume of the ambient air surrounding the device under test and airflow
5. Whether other surfaces are in close proximity to the device being tested
Due to the charge profile of Li-Ion and Li-Pol batteries the maximum power dissipation is typically seen at the
beginning of the charge cycle when the battery voltage is at its lowest. Typically after fast charge begins the pack
voltage increases to ≉3.4V within the first 2 minutes. The thermal time constant of the assembly typically takes a
few minutes to heat up so when doing maximum power dissipation calculations, 3.4V is a good minimum voltage
to use. This is verified, with the system and a fully discharged battery, by plotting temperature on the bottom of
the PCB under the IC (pad should have multiple vias), the charge current and the battery voltage as a function of
time. The fast charge current will start to taper off if the part goes into thermal regulation.
The device power dissipation, P, is a function of the charge rate and the voltage drop across the internal
PowerFET. It can be calculated from the following equation when a battery pack is being charged:
P = [V(IN) – V(OUT)] × I(OUT) + [V(OUT) – V(BAT)] × I(BAT)
(8)
The thermal loop feature reduces the charge current to limit excessive IC junction temperature. It is
recommended that the design not run in thermal regulation for typical operating conditions (nominal input voltage
and nominal ambient temperatures) and use the feature for non typical situations such as hot environments or
higher than normal input source voltage. With that said, the IC will still perform as described, if the thermal loop
is always active.
11.3.1 Leakage Current Effects on Battery Capacity
To determine how fast a leakage current on the battery will discharge the battery is an easy calculation. The time
from full to discharge can be calculated by dividing the Amp-Hour Capacity of the battery by the leakage current.
For a 0.75AHr battery and a 10μA leakage current (750 mAHr / 0.010 mA = 75000 hours), it would take 75k
hours or 8.8 years to discharge. In reality the self discharge of the cell would be much faster so the 10μA
leakage would be considered negligible.
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12 Device and Documentation Support
12.1 Receiving Notification of Documentation Updates
To receive notification of documentation updates, navigate to the device product folder on ti.com. In the upper
right corner, click on Alert me to register and receive a weekly digest of any product information that has
changed. For change details, review the revision history included in any revised document.
12.2 Community Resources
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
12.3 Trademarks
E2E is a trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
12.4 Electrostatic Discharge Caution
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
12.5 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
13 Mechanical, Packaging, and Orderable Information
The following pages include mechanical packaging and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
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PACKAGE OPTION ADDENDUM
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10-Dec-2018
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
Lead/Ball Finish
MSL Peak Temp
(2)
(6)
(3)
Op Temp (°C)
Device Marking
(4/5)
BQ21040DBVR
ACTIVE
SOT-23
DBV
6
3000
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
0 to 125
130E
BQ21040DBVT
ACTIVE
SOT-23
DBV
6
250
Green (RoHS
& no Sb/Br)
Call TI
Level-1-260C-UNLIM
0 to 125
130E
(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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