SLUS527 – DECEMBER 2002
FEATURES
D Designed for Off-Line Charger Design for
D
D
D
D
D
D
D
D
D
DESCRIPTION
Single-Cell Li-Ion Packs
Provides Control Feedback to a Primary-Side
Controller
Robust Battery Insertion and Removal
Detection
Charge Current and Voltage Regulation
Feedback to Primary-Side for High-Accuracy
Charging
Charge Termination by Minimum Current and
Time
Pre-Charge Conditioning Regulator with
Safety Timer
Charge Status Outputs for LED or Host
Processor Interface Indicates Chargein-Progress, Charge Completion, and Fault
Conditions
Temperature Monitoring Before and During
Charge
Short-Circuit Protection
Small, 14-Pin TSSOP Package
APPLICATIONS
D Cradle Chargers for Digital Cameras
D Desktop Chargers
D Handheld Devices
The bq24901 Li-Ion charge management devices
are designed specifically for off-line charger
applications. The bq24901 resides on the
secondary-side of the transformer and provides
the control feedback to a variety of primary side
controllers. The bq24901 offers current or voltage
regulation feedback, temperature monitoring,
charge status, and adjustable charge termination,
in a single monolithic device. During
battery-absent or charge-complete conditions,
the bq24901 continuously regulates the
secondary-side voltage, used as VCC supply to
the device.
The bq24901 features a time-limited precon–
ditioning phase to condition deeply discharged
cells. The pre-conditioning phase is achieved by
linear regulation in the secondary side. Following
preconditioning, the bq24901 regulates the
charge current to the value set by the external
current sense resistor. Once the battery reaches
the charge voltage, the voltage regulation loop
takes over and completes the charge cycle. The
accuracy of the voltage regulation is better than
±30mV. Charge is terminated based on minimum
current. The minimum current level is set through
TADJ pin. An internal five-hour charge timer
provides a backup for charge termination.
The bq24901 is designed to reliably detect battery
insertion and removal conditions, including packs
with open protectors. Other standard features
include a recharge feature activated when the
battery voltage falls below the VRCH threshold.
Copyright 2002, Texas Instruments Incorporated
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1
SLUS527 – DECEMBER 2002
DESCRIPTION (continued)
In addition to the standard features, the bq24901 offers battery temperature monitoring and status display. The
temperature-sense circuit continuously measures battery temperature using an external thermistor and
suspends charge until the battery temperature is within the user–defined thresholds. The STAT pins indicate
conditions of operation of the charger. These outputs can be used to drive an LED or interface to a host
microcontroller.
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.
ORDERING INFORMATION
TA
CHARGE REGULATION
VOLTAGE
PACKAGE DEVICES(1)
TOP SIDE MARKINGS
–20°C to 85°C
4.2 V
bq24901PW
bq24901
(1) The PW package is also available taped and reeled. Add an R suffix to the device type (i.e., bq24901PWR) for quantities of 2,500 devices per
reel.
PACKAGE DISSIPATION RATING TABLE
PACKAGE
θJA
TA ≤ 25°C
POWER RATING
DERATING FACTOR
ABOVE TA = 25°C
PW
110°C/ W
907 mW
9.07 mW/°C/
ABSOLUTE MAXIMUM RATINGS
over operating free-air temperature range unless otherwise noted(1)
Supply voltage, VCC
I
Input
t voltage
lt
range, VI
bq24901
UNIT
with respect to VSS
11.5
V
SNS, BAT, STAT1, STAT2, VCOMP, ICOMP, SCOMP, OPTD, CC
(all with respect to Vss)
11.5
TADJ, VREF (all with respect to Vss)
TS (with respect to Vss)
Output sink/source current, IO
O tp t sink current
Output
c rrent
V
7
–0.3 to VCC + 0.3 V
STAT1, STAT2, OPTD
20
CC
80
VREF
1
mA
Operating free-air temperature range, TA
–40 to 100
Junction temperature range, TJ
–40 to 125
Storage temperature, Tstg
–65 to 150
°C
Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds
300
(1) Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only,
and functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is
not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
RECOMMENDED OPERATING CONDITIONS
MIN
Supply voltage, VCC
Operating free-air temperature, TA
2
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MAX
UNIT
3
10
V
–20
85
°C
SLUS527 – DECEMBER 2002
ELECTRICAL CHARACTERISTICS
Over recommended operating free-air temperature and supply voltage (unless otherwise noted)
TEST CONDITIONS
PARAMETER
MIN
TYP
MAX
UNIT
SUPPLY CURRENT
ICC(VCC)
IIB(BAT)
Input current
IIB(TS)
IIB(SNS)
Input bias current on TS pin
Input bias current on BAT pin
Input bias current on SNS pin
IIB(TADJ)
Input bias current on TADJ pin
BATTERY VOLTAGE and VCC REGULATION
VO(REG)
VCC
Output voltage
VCC > VCC(min)
VI(BAT) > VO(REG), when not in charge
2
VI(TS) = 2.5 V
VCC = 6 V,
VI(SNS) = 6 V when not in charge
VI(TADJ) = VREF
1
0°C ≤ TA ≤ 70°C
Supply voltage
mA
1
1
µA
A
1
4.17
4.20
4.23
5.8
6.0
6.3
184
200
216
mV
VCC
V
V
CURRENT REGULATION
Current regulation threshold
voltage
V(SNS)
Voltage at pin SNS relative to BAT,
0°C ≤ TA ≤ 70°C, V(LOWV)≤ V(SNS)≤ VO(REG)
Input common mode range on
SNS pin
V(UVT)
PRE-CHARGE AND SHORT-CIRCUIT CURRENT REGULATION
Pre-charge voltage threshold
ISC
Short-circuit current
CHARGE TERMINATION DETECTION
Charge termination current detect
threshold
V(ITERM)
Voltage at pin SNS relative to BAT pin, 0°C ≤
TA ≤ 70°C
V(UVT) ≤ VI(BAT) ≤ V(LOWV)
0°C ≤ TA ≤ 70°C, 0 ≤ VI(BAT) ≤ V(UVT)
Voltage at pin SNS relative to BAT pin,
0°C ≤ TA ≤ 70°C
TADJ pin tied to VREF pin,
VI(SNS) = VO(REG)VI(BAT) > V(RCH)
Voltage at pin SNS relative to BAT pin,
0°C ≤ TA ≤ 70°C
TADJ pin tied to VSS pin,
VI(SNS) = VO(REG)VI(BAT) > V(RCH)
10
20
5.4
16
20
30
mV
30.0
mA
24
mV
7.5
10.0
12.5
VO(REG)
–210
VO(REG)
– 160
VO(REG)
– 110
V(EN-TERM)
Enable termination voltage
(VI(SNS) – VI(BAT)) < V(ITERM) , VBAT increasing
above threshold
t(TRMDET2)
Falling-edge delay for termination
detection
(VSNS – VBAT) increasing above threshold,
VI(BAT) > V(EN–TERM),
100 ns fall time
2 mV overdrive
100
µs
t(TRMDET1)
Rising-edge delay for termination
detection
(VSNS – VBAT) increasing above threshold,
VI(BAT) > V(EN–TERM),
100 ns fall time
2 mV overdrive
20
ms
V
TEMPERATURE COMPARATOR
V(LTF)
V(HTF)
Cold temperature threshold voltage
V(TCO)
Cutoff temperature threshold voltage
Hot temperature threshold voltage
LTF hysteresis
VTS,
VTS,
VCC ≥ 3.5 V
VCC ≥ 3.5 V
VTS,
VCC ≥ 3.5 V
Hysteresis for LTF threshold voltage
72.6
73.5
74.1
33.7
34.4
35.1
28.7
29.3
29.9
0.1
0.6
1.1
3.00
3.05
3.15
%VCC
LOW BATTERY VOLTAGE (LOWV) THRESHOLD COMPARATOR
V(LOWV)
(1)
V
Ensured by design. Not production tested.
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3
SLUS527 – DECEMBER 2002
ELECTRICAL CHARACTERISTICS (continued)
Over recommended operating free-air temperature and supply voltage (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
BATTERY RECHARGE THRESHOLD (VRCH) COMPARATOR
V(RCH)
VO(REG)
– 0.24
Recharge threshold voltage
VO(REG)
– 0.12
V
V
POWER-ON RESET (POR)
V(POR)
TIMERS
POR threshold voltage
t(PRECHG)
Precharge time
t(CHG)
Charge time
VI(BAT) < V(LOWV)
V(LOWV) < VI(BAT) < VO(REG),
(VI(SNS) – VI(BAT)) < V(ITERM)
2.60
2.70
2.85
1,350
1,800
2,250
13,500
18,000
22,500
s
OPTO-DRIVER PIN (OPTD)
VSAT(OPTD)
Output saturation voltage
I(OPTDLKG)
Opto-driver leakage current
gM
Transconductance
Gain-bandwidth product
IO(OPTD) = 10 mA
V(OPTD) = 5 V,
VI(BAT) < VO(REG)
VCC = 5.8 V,
(VI(SNS) – VI(BAT)) < 184 mV
IO(OPTD) = 5 mA
IO(OPTD) = 5 mA, RLOAD = 100 Ω
5
100
mV
100
µA
500
S
1
MHz
DISCHARGE CURRENT, DISCHARGE VOLTAGE, CONDITION CURRENT AND WAKE CURRENT
1 V≤ VI(BAT) ≤ 4.2 V
I(DISCHG)
t(DISCHG1)
Discharge current
60
300
800
Discharge time 1
250
310
370
t(DISCHG2)
V(DISCHG)
Discharge time 2
20
25
30
1.5
2.0
2.5
Discharge voltage(1)
0.8
Batter detection current
Battery
c rrent
I(DETECT_min) at VCC = 5.8 V,VI(BAT) = 4.2 V
I(DETECT_max) at VCC = 6 V, VI(BAT) = 0 V
0.8
I(WK_SRC)
current source 1
Wake current,
I(WK_SRC_min) at VCC = 5.8 V,VI(BAT) = 4.2 V
I(WK_SRC_max) at VCC = 6 V, VI(BAT) = 0 V
Wake current,
c rrent source
so rce 2
I(WK_SINK_min) at VCC = 5.8 V,
VI(BAT) = 4.2 V
I(WK_SINK_max) at VCC = 6 V,VI(BAT) = 0 V
0
I(WK_SINK)
I(DETECT)
t(WK)
Wake time
CHARGE STATUS OUTPUT (STAT1/STAT2)
VOL(STATx) Low-level output saturation voltage
VOLTAGE REFERENCE OUTPUT (VREF)
VREF voltage threshold
V
mA
30
1000
IO(STATx) = 10 mA, VCC ≥ 3.5 V
0°C ≤ TA ≤ 70°C
ms
30
100
0 V < IO(VREF) < 500 µA,
µA
1.18
125
µA
A
150
ms
0.5
V
1.22
V
CHARGE CONTROL OUTPUT (CC)
VOL
COUT
Low-level output voltage (FstChg)
Output capacitance
IO(CC) = 40 mA (sink)
LDO to BAT,
LDO to VSS
0.45
V
0.1
10.0
µF
2.00
2.15
V
UNDERVOLTAGE THRESHOLD SHORT-CIRCUIT PROTECTION
V(UVT)
(1)
4
Undervoltage threshold voltage
Ensured by design. Not production tested.
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SLUS527 – DECEMBER 2002
PW PACKAGE†
(TOP VIEW)
OPTD
VCC
SCOMP
ICOMP
VCOMP
STAT1
STAT2
1
2
3
4
5
6
7
14
13
12
11
10
9
8
VSS
CC
SNS
BAT
TS
VREF
TADJ
TERMINAL FUNCTIONS
TERMINAL
NAME
NO.
I/O
DESCRIPTION
BAT
11
I
Battery voltage sense input. This input is tied directly to the positive side of the battery pack.
CC
13
O
Charge control output. CC is an open-drain pulldown output that is used to drive an external pass transistor for charge current and voltage control
ICOMP
4
I
Current loop compensation. This is the compensation for the fast charge current regulation loop.
OPTD
1
O
Optocoupler driver output. This open-collector output is used to provide feedback to the primary side
by driving an external optocoupler.
SCOMP
3
I
Supply loop compensation. This is the compensation for the VCC supply regulation loop.
SNS
12
I
Current sense input. Battery current is sensed via the voltage developed on this pin by an external
sense resistor.
STAT1
6
O
Charge status output 1 (open drain)
STAT2
7
O
Charge status output 2 (open drain)
TADJ
8
I
Termination adjust. This input is used to set the minimum current termination level during voltage regulation phase.
TS
10
I
Temperature sense Input. Input for an external battery temperature monitoring.
VCC
2
I
VCOMP
5
I
VCC supply input.
Voltage loop compensation. This is the compensation for the battery regulation loop
VREF
9
O
Voltage reference output. This buffered output provides the internal bandgap voltage.
VSS
14
–
Ground input.
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5
SLUS527 – DECEMBER 2002
FUNCTIONAL BLOCK DIAGRAM
VCC
CC
SNS
2
13
12
11 BAT
+
+
SHUTDOWN
POR
FILTER
SHUTDOWN
ITERM
FILTER
DECODE LOGIC AND
RAMP CONTROL
PRECHARGE
Term_det_EN
(to SM)
VUVT
TERMINATION
ILIM BYPASS
SUSPEND
TS 10
BAT_PRS_wake
(to SM)
BAT
LTF
FILTER
VHEG – 100 mV
SHUT
DOWN
WAKE_SRC
WAKE
HTF
BAT
VCC
TCO
VREF
TADJ
9
8
+
CHARGE
DISCHARGE
CHARGE CONTROL,
TIMER,
AND
DISPLAY LOGIC
VBANDGAP
ICHARGE_SINK
IDSCHRG
TERMINATION
PRECHARGE
SUSPEND
FASTCHARGE
ITERM
START–UP
LOGIC
VIBAT
Term_det_EN BAT_PRS_wake
6
STAT1
7
STAT2
4
ICOMP
5
VCOMP
DISC_RES
VCC
+
SHUTDOWN
SCOMP
3
OPTD
1
FILTER
RAMP
CONTROL
VICHG
FASTCHARGE
+
+
VBANDGAP
VBANDGAP
SHUTDOWN
VSS
SUSPEND
14
DISC_RES
TERMINATION
UDG–02182
6
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SLUS527 – DECEMBER 2002
APPLICATION INFORMATION
The bq24901 supports a precision current and voltage regulated li-ion charging system suitable for single-cells.
Figure 1 shows the typical application diagram, Figure 2 shows a typical charge profile, and Figure 3 shows an
operational flow chart.
XMFR
D2
OPTO1
L1
D1
N1
Q1
COUT
N2
C1
bq24901
C3 N3
PRIMARY
SIDE
CONTROLLER
RS
1
OPTD
2
VCC
3
VSS 14
OPTO1
CC
13
SCOMP
SNS
12
4
ICOMP
BAT 11
5
VCOMP
6
STAT1
VREF
9
7
STAT2
TADJ
8
VCC
+
TS 10
BATTERY PACK
VCC
VCC
UDG–02180
Figure 1. Typical Application Diagram
Current Regulation Phase
Voltage Regulation Phase
Regulation Voltage
Regulation Current
Charge
Voltage
Minimum Charge Voltage
Charge
Current
Pre-Conditioning
and Taper Detect
Fast Charge Timer
Pre-Charge
Timer
Figure 2. Typical Charge Profile
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SLUS527 – DECEMBER 2002
APPLICATION INFORMATION
POR
Check for battery
Presence
Battery
Present?
No
Indicate BATTERY
ABSENT
Yes
Suspend charge
TS pin
in LTF to HTF
range?
No
Indicate CHARGE
SUSPEND
Yes
VBAT
