TI1 BQ24901 Offlne application Datasheet

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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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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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 <VLOWV
Yes
Regulate
IPRECHG
Reset and Start
T30min timer
Indicate Charge–
In–Progress
No
Suspend charge
Reset and Start
T5hr timer
TS pin
in LTF to TCO
range?
Regulate
Current or Voltage
Yes
No
Indicate CHARGE
SUSPEND
No
TS pin
in LTF to HTF
range?
Indicate Charge–
In–Progress
No
VBAT <VLOWV
Yes
Suspend charge
TS pin
in LTF to TCO
range?
Yes
No
Indicate CHARGE
SUSPEND
Yes
T30min
Expired?
No
No
TS pin
in LTF to HTF
range?
T5hr Expired?
Yes
No
Yes
Reset and Start
T30min timer
Yes
Reset and Start
T5hr timer
VBAT <VLOWV
Yes
No
– Fault Condition
– Enable IDETECT
No
ITERM detection?
Indicate Fault
No
Yes
– Turn off charge
– Enable IDISCHG for
tDISCHG2
Battery
Replaced?
Indicate Charge–
In–Progress
Yes
Charge Complete
VBAT < VRCH ?
No
Indicate DONE
Battery Removed
Yes
Indicate BATTERY
ABSENT
Figure 3. Operational Flow Chart
8
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SLUS527 – DECEMBER 2002
APPLICATION INFORMATION
Charge Qualification and Pre-Conditioning
The bq24901 starts a charge cycle when power is applied and a battery is present. Charge qualification is based
on battery temperature and voltage. The device suspends charge if the battery temperature is outside the VLTF
to VHTF and waits until the battery temperature is within the allowed range. The device also checks the battery
voltage. If the battery voltage is below the low-voltage threshold, VLOWV, the device use pre-conditioning
current, IPRECHG, to charge the battery.
Temperature Sense (TS) Input
The bq24901 continuously monitors battery temperature by measuring the voltage between the TS pin and Vss.
A negative temperature coefficient thermistor (NTC) and an external voltage divider typically develop this
voltage. The bq24901 compares this voltage against its internal thresholds to determine if charging is allowed.
To initiate a charge cycle, the battery temperature must be within the VLTF to VHTF thresholds. If battery
temperature is outside of this range, the device suspends charge and waits until the battery temperature is within
the VLTF to VHTF range. During the charge cycle (both pre-charge and fast charge) the battery temperature must
be within the VLTF to VTCO thresholds. If battery temperature is outside of this range, the bq24901 suspends
charge and waits until the battery temperature is within the VLTF to VHTF range. The device suspends charge
by turning off the CC pin and holding the timer value (i.e. timers are not reset during a suspend condition).
Figure 4 summarizes this operation.
VCC
Charge Suspend
VLTF
VHTF
VTCO
Charge Suspend
Temperature Range
to Initiate Charge
Temperature Range
During Charge Cycle
Charge Suspend
Charge Suspend
VSS
Figure 4. Temperature Sense Input Thresholds
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SLUS527 – DECEMBER 2002
APPLICATION INFORMATION
VCC Regulation
During the following conditions the bq24901 regulates the VCC power and the device remains active. Loop
compensation for VCC regulation is achieved through SCOMP pin.
D
D
D
D
D
Battery absent condition
Pre-charge
Charge suspend
Fault
Done
Voltage Monitoring and Regulation
Voltage regulation feedback is through pin BAT. This input is tied directly to the positive side of the battery pack.
Loop compensation for voltage regulation is achieved through VCOMP pin.
Current Regulation
The bq24901 provides current regulation while the battery pack voltage is less than the regulation voltage,
VREG. The device monitors charge current at the SNS input by the voltage drop across an external
sense-resistor, RSNS, in series with the battery pack. Charge current feedback, applied through pin SNS,
maintains regulation around a threshold of VSNS. The formula in equation (1) calculates the value of the sense
resistor.
R SNS +
V (SNS)
I (CHG)
(1)
where:
D I(CHG) is the desired charging circuit
Loop compensation for current regulation is accomplished via the ICOMP pin.
10
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SLUS527 – DECEMBER 2002
APPLICATION INFORMATION
Current Regulation Ramp-Up and Ramp-Down
Both current regulation loops ramp up and down when transitioning from pre-charge to fast charge, and when
going in and out of fault/suspend mode where the LDO needs to be turned hard on or off. Figure 5 demonstrates
the typical stepping ramp.
300
Fastcharge
275
VFB – Feedback Voltage – mV
Pre-Charge
250
225
Pre-Charge
Regulator
Reference
200
150
125
100
75
Fastcharge
Regulator
Reference
50
25
0
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
75
tCHG – Time – ms
Step Count
Figure 5. Typical Current Regulation Ramp From/To Pre-Charge/Fastcharge
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SLUS527 – DECEMBER 2002
APPLICATION INFORMATION
Battery Insertion and Removal Detection
The bq24901 reliably detects insertion and removal of battery packs under various conditions. This includes
the battery packs with open or closed protectors. Figure 6 shows the flow chart. Table 1 provides a summary
of various battery insertion and removal conditions.
Begin Battery
Detection
Enable IDSCHG
for tDSCHG
Yes
VBAT >
VDSCHG
?
No
Enable
IWAKE1 orWAKE2
I
for tWAKE
In Voltage
Regulation
?
Yes
Battery
Absent
No
Battery
Present
Figure 6. Battery Detection Summary
12
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SLUS527 – DECEMBER 2002
APPLICATION INFORMATION
Table 1. State Machine Status
STATE MACHINE
STATUS
BATTERY PACK
STATUS
1
Following power-on
reset (POR)
New pack insertion.
2
Following POR
New deeply-discharged
battery (with an open
protector inserted).
3
Pre-conditioning
Pack is removed.
4
Fastcharge
(current or voltage
regulation)
Pack is removed.
5
Charge suspend
Pack is removed.
6
Charge suspend
Pack is removed. A new
pack with normal temperature inserted.
7
Charge suspend
Pack is removed. A new
pack with abnormal
temperature inserted.
8
Charge suspend
Pack is removed. A pack
with open protector and normal temperature inserted
9
Charge suspend
Pack is removed. A pack with
open protector and abnormal
temperature inserted
10
Timer fault
Pack remains in charger.
ACTION
h The device remains in the battery presence detection loop until a new battery is
detected.
h Depending on the battery voltage, the device either enters pre–charge or fast
charge.
h The device remains in the battery presence detection loop until a new battery is
detected.
h Depending on the battery voltage, the device either enters pre–charge or fast
charge.
h The device enters fast charge (since the output capacitor rises above V
LOWV) and
terminates immediately due to ITERM detection.
h The device then enables I
DISCHG for tDISCHG2. In the absence of a battery, the
BAT voltage falls below VRCH, prompting the device to indicate BATTERY
ABSENT. If the battery is present the BAT voltage does not fall below VRCH and
therefore device assumes a battery is still connected and indicates DONE on
STAT pins.
h The device terminates immediately due to I
TERM detection.
h The device then enables I
DISCHG for tDISCHG2. In the absence of a battery, the
BAT voltage falls below VRCH, prompting the device to indicate BATTERY
ABSENT. If the battery is present the BAT voltage does not fall below VRCH and
therefore device assumes a battery is still connected and indicates DONE on
STAT pins.
h The device remains the charge suspend mode as long as the TS pin voltage is
outside the VLTF to VHTF range.
h The device leaves the charge-suspend mode and resumes charging depending
on the battery voltage.
h The device resets the timers only if it enters a charge mode different from where
the initial charge suspend condition happened (for instance from pre-charge to
fast or vice versa)
h The device remains the charge suspend mode as long as the TS pin voltage is
outside the VLTF to VHTF range.
h Once temperature returns to normal, item 6 in this table applies.
h The device leaves the charge suspend mode.
h The device enters pre-charge (since the voltage is below V
LOWV). This action
closes the protector and charging resumes.
h The device remains the charge suspend mode as long as the TS pin voltage is
outside the VLTF to VHTF range.
h Once temperature returns to normal, item 8 in this table applies.
h The device remains in the fault condition until POR or battery removal is detected.
11
Timer fault
Pack is removed.
h Once in the fault mode, the device applies the I
DETECT current to the output. The
purpose of this current is to detect the removal of the pack.
h If voltage regulation can be maintained with I
DETECT current, the device assumes
the pack has been removed (and only output capacitor is present).
h The device then awaits battery insertion as outlined item 1 of this table.
12
Timer fault
Pack is removed. A new
pack is inserted.
h See item 11 in this table.
13
Timer fault
Pack is removed. A new
pack with open protector is
inserted.
h See items 11 and 12 in this table.
14
Timer fault
Pack remains in charger.
15
Done
Pack is removed.
h The bq24901 in the Done state as long as the pack voltage is above the V
RCH
threshold. While in the done state there is no current flow to the battery (zero
current)
h While in the DONE state, the device monitors the BAT voltage and initiates a new
cycle once the BAT voltage falls below VRCH threshold (this happens as the output
capacitor discharges through the input leakage on the BAT pin).
h While in the DONE state, the device monitors the BAT voltage and initiates a new
cycle once the BAT voltage falls below VRCH threshold (this happen as the output
capacitor discharges through the input leakage on the BAT pin).
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13
SLUS527 – DECEMBER 2002
APPLICATION INFORMATION
Charge Termination and Re-Charge
The bq24901 monitors the charging current during voltage regulation. The device declares a DONE condition
and terminates charge when then the current tapers off to charge termination current detect threshold. The
charge termination level is set through TADJ pin as detailed in Table 2 and Figure 7.
Table 2. Charge Termination Adjustment
TADJ INPUT
TERMINATION LEVEL
V SNS
Connected directly to VREF pin
10
V SNS
Connected directly to VSS pin
Connected directly to the mid-point of a resistor
divider between VREF and VSS pins (see Figure 8)
ǒ
20
Ǔ ǒ Ǔ
R2 V SNS
V SNS
)
20
20 (R1 ) R2)
NOTE: VSNS is the current regulation threshold.
VREF
R1
TADJ
R2
Figure 7. Charge Termination Adjustment Connection
The bq24901 also features two internal digital filters for detecting termination threshold. The digital filters, with
tTERMDET1 and tTERMDET2 response times, are designed to reduce the possibility of early termination due to line
or switching frequency noise.
A new charge cycle is initiated when one of the following conditions are detected:
1. Battery voltage falls below the VRCH threshold
2. New battery insertion (once battery falls below the VRCH threshold)
3. Power-on reset (POR)
14
www.ti.com
SLUS527 – DECEMBER 2002
APPLICATION INFORMATION
Charge Timers
The bq24901 provides two charge timers to protect the battery during pre-charge and charge phases. The first
timer, T30min, is reset at the beginning of a new charge cycle and initiated in the pre-charge phase. During
pre-charge, if the timer expires before the battery rises above the VLOWV threshold, a fault condition is
annunciated. Power-on reset or battery replacement clears the fault.
The second timer, T5hr, is reset at the beginning of a new charge cycle and is initiated at the beginning of the
charge phase. A fault condition is annunciated if the battery current fails to reach charge termination current
detect threshold, ITERM, during charge. Power-on reset or battery replacement clears the fault.
Charge Status Display
The open-drain STAT1 and STAT2 outputs indicate various charger operations as shown in the Table 3.
Table 3. Charge Termination Adjustment
CHARGE STATE
STAT1
OFF(1)
STAT2
Charge-in-progress
ON
OFF
Charge done
OFF
ON
Charge suspend (temperature)
OFF
OFF
Battery absent
OFF
Timer fault
OFF
OFF
(1) OFF means the open-drain output transistor on the STATx pin
is in an off state.
www.ti.com
15
PACKAGE OPTION ADDENDUM
www.ti.com
21-Mar-2013
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package Qty
Drawing
Eco Plan
Lead/Ball Finish
(2)
MSL Peak Temp
Op Temp (°C)
Top-Side Markings
(3)
(4)
BQ24901PW
OBSOLETE
TSSOP
PW
14
TBD
Call TI
Call TI
-20 to 85
BQ24901PWG4
OBSOLETE
TSSOP
PW
14
TBD
Call TI
Call TI
-20 to 85
(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)
Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability
information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that
lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between
the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight
in homogeneous material)
(3)
MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4)
Only one of markings shown within the brackets will appear on the physical device.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
Addendum-Page 1
Samples
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