SLUS025F − MAY 2001 − REVISED JULY 2002
FEATURES
D Ideal for Single (4.1 V or 4.2 V) and Dual-Cell
D
D
D
D
D
D
D
D
D
D
D
D
D
DESCRIPTION
(8.2 V or 8.4 V) Li-Ion or Li-Pol Packs
Requires Small Number of External
Components
0.3 V Dropout Voltage for Minimizing Heat
Dissipation
Better Than ±1% Voltage Regulation Accuracy
With Preset Voltages
AutoCompt Dynamic Compensation of
Battery Pack’s Internal Impedance to Reduce
Charge Time
Optional Cell-Temperature Monitoring Before
and During Charge
Integrated Voltage and Current Regulation
With Programmable Charge-Current and Highor Low-Side Current Sensing
Integrated Cell Conditioning for Reviving
Deeply Discharged Cells and Minimizing Heat
Dissipation During Initial Stage Of Charge
Charge Status Output for Single or Dual Led
or Host Processor Interface
Automatic Battery-Recharge Feature
Charge Termination by Minimum Current
Automatic Low-Power Sleep Mode When VCC
Is Removed
EVMs Available for Quick Evaluation
Packaging: 8-Pin SOIC, 8-Pin TSSOP, 8-Pin
MSOP
The BENCHMARQ bq2057 series advanced
Lithium-Ion (Li-Ion) and Lithium-Polymer (Li-Pol) linear
charge-management ICs are designed for costsensitive and compact portable electronics. They
combine high-accuracy current and voltage regulation,
battery conditioning, temperature monitoring, charge
termination, charge-status indication, and AutoComp
charge-rate compensation in a single 8-pin IC. MSOP,
TSSOP, and SOIC package options are offered to fit a
wide range of end applications.
The bq2057 continuously measures battery
temperature using an external thermistor. For safety,
the bq2057 inhibits charge until the battery temperature
is within user-defined thresholds. The bq2057 then
charges the battery in three phases: conditioning,
constant current, and constant voltage. If the battery
voltage is below the low-voltage threshold, V(min), the
bq2057 precharges using a low current to condition the
battery. The conditioning charge rate is approximately
10% of the regulation current. The conditioning current
also minimizes heat dissipation in the external passelement during the initial stage of the charge. After
conditioning, the bq2057 applies a constant current to
the battery. An external sense-resistor sets the current.
The sense-resistor can be on either the high or low side
of the battery without additional components. The
constant-current phase continues until the battery
reaches the charge-regulation voltage.
bq2057xSN or bq2057xTS
SOIC (SN) or TSSOP (TS) PACKAGE
(TOP VIEW)
SNS
BAT
VCC
TS
1
8
2
7
3
6
4
5
COMP
CC
VSS
STAT
bq2057xDGK
MSOP (DGK) PACKAGE
(TOP VIEW)
VCC
TS
STAT
VSS
1
8
2
7
3
6
4
5
BAT
SNS
COMP
CC
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
AutoComp is a trademark of Texas Instruments.
!"#$%! & '("")% $& ! *(+'$%! ,$%)"!,('%& '!!"# %! &*)''$%!& *)" %.) %)"#& ! )/$& &%"(#)%&
&%$,$", 0$""$%1- "!,('%! *"!')&&2 ,!)& !% )')&&$"+1 '+(,)
%)&%2 ! $++ *$"$#)%)"&-
Copyright 2002, Texas Instruments Incorporated
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1
SLUS025F − MAY 2001 − REVISED JULY 2002
DESCRIPTION (continued)
The bq2057 then begins the constant-voltage phase. The accuracy of the voltage regulation is better than ±1%
over the operating-temperature and supply-voltage ranges. For single and dual cells, the bq2057 is offered in
four fixed-voltage versions: 4.1 V, 4.2 V, 8.2 V, and 8.4 V. Charge stops when the current tapers to the charge
termination threshold, I(TERM). The bq2057 automatically restarts the charge if the battery voltage falls below
the V(RCH) threshold.
The designer also may use the AutoComp feature to reduce charging time. This proprietary technique allows
safe and dynamic compensation for the internal impedance of the battery pack during charge.
AVAILABLE OPTIONS
PACKAGE
TA
−20°C to 70°C
CHARGE REGULATION
VOLTAGE
SOIC
(SN)
MSOP†
(DGK)
4.1 V
Not available
bq2057TS
bq2057DGK
4.2 V
bq2057CSN
bq2057CTS
bq2057CDGK
8.2 V
Not available
bq2057TTS
8.4 V
bq2057WSN
bq2057WTS
† Note the difference in pinout for this package.
2
TSSOP
(TS)
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Not available
SLUS025F − MAY 2001 − REVISED JULY 2002
function block diagram
VCC
Internal Reference
VCC
_
DONE
+
Sleep Mode
_
BAT
V-Control
+
G(comp)
+
_
CC
I-Control
Voltage Regulation
COMP
Battery
Recharge
VCC
+
_
VCC
Battery
Conditioning
Control
Block
STAT
_
+
TS
TS2 Trip
_
+
TS1 Trip
I-Control
0.5 VCC
_
High/Low SNS Set
+
SNS
VCC−V(SNS)
+
_
Current Regulation
VSS−V(SNS)
+
_
Charge Termination
VSS
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3
SLUS025F − MAY 2001 − REVISED JULY 2002
Terminal Functions
TERMINAL
NO.
NAME
I/O
DESCRIPTION
SOIC (SN) and
TSSOP (TS)
MSOP
(DGK)
BAT
2
8
I
Voltage sense input
CC
7
5
O
Charge control output
COMP
8
6
I
Charge-rate compensation input (AutoComp)
SNS
1
7
I
Current sense input
STAT
5
3
O
Charge status output
TS
4
2
I
Temperature sense input
VCC
3
1
I
Supply voltage
VSS
6
4
Ground
detailed description
current-sense input
Battery current is sensed via the voltage developed on this pin by an external sense resistor. The external
resistor can be placed on either the high or low side of the battery. (See schematics for details.)
battery-voltage input
Voltage sense-input tied directly to the positive side of the battery.
temperature sense input
Input for an external battery-temperature monitoring circuit. Connecting this input to VCC/2 disables this feature.
charge-status output
3-state indication of charge in progress, charge complete, and temperature fault or sleep mode.
charge-control output
Source-follower output that drives an external pass-transistor (PNP or P-channel MOSFET) for current and
voltage regulation.
charge-rate compensation input
Sets the charge-rate compensation level. The voltage-regulation output may be programmed to vary as a
function of the charge current delivered to the battery.
supply voltage input
Power supply input and current reference for high-side sensing configuration.
4
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SLUS025F − MAY 2001 − REVISED JULY 2002
absolute maximum ratings over operating free-air temperature (unless otherwise noted)†
Supply voltage (VCC with respect to GND) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −0.3 to +18 V
Input voltage, SNS, BAT, TS, COMP (all with respect to GND) . . . . . . . . . . . . . . . . . . . . . . . . . . −0.3 V to VCC+0.3 V
Sink current (STAT pin) not to exceed PD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 mA
Source current (STAT pin) not to exceed PD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 mA
Output current (CC pin) not to exceed PD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 mA
Total power dissipation, PD (at 25°C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300mW
Operating free-air temperature range, TA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −20°C to 70°C
Storage temperature range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −40°C to 125°C
Lead temperature (soldering, 10 s) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300°C
† 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.
DISSIPATION RATING TABLE
PACKAGE
DGK
DERATING FACTOR
ABOVE TA = 25°C
TA ≤ 25°C
POWER RATING
3.4 mW/°C
424 mW
TA = 70°C
POWER RATING
271 mW
recommended operating conditions
MIN
MAX
Supply voltage, VCC
4.5
15
UNIT
V
Operating free-air temperature range, TA
−20
70
°C
electrical characteristics over recommended operating free-air temperature range (unless
otherwise noted)
PARAMETER
I(VCC)
VCC Current
I(VCCS)
VCC Sleep current
IIB(BAT)
IIB(SNS)
Input bias current on BAT pin
IIB(TS)
IIB(COMP)
Input bias current on TS pin
Input bias current on SNS pin
Input bias current on COMP pin
TEST CONDITIONS
MIN
VCC > VCC(min), Excluding external loads
For bq2057 and bq2957C,
V(BAT) ≥ V(min), V(BAT) – VCC ≥ 0.8 V
TYP
MAX
2
4
3
6
UNIT
mA
µA
A
For bq2057T and bq2957W,
V(BAT) ≥ V(min), V(BAT) – VCC ≥ 0.8 V
10
V(BAT) = V(REG)
V(SNS)= 5 V
1
µA
5
µA
V(TS) = 5 V
V(COMP) = 5 V
5
µA
5
µA
BATTERY VOLTAGE REGULATION
VO(REG)
Output voltage
bq2057, See Notes 1, 2, 3
4.059
4.10
4.141
bq2057C, See Notes 1, 2, 3
4.158
4.20
4.242
bq2057T, See Notes 1, 2, 3
8.119
8.20
8.282
bq2057W, See Notes 1, 2, 3
8.317
8.40
8.484
V
NOTES: 1. For high-side current sensing configuration
2. For low-side current sensing configuration, the tolerance is ±1% for TA = 25°C and ±1.2% for −20°C ≥ TA ≥ 70°C
3. V(BAT)+0.3 V ≤ VCC ≤ VCC(max)
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5
SLUS025F − MAY 2001 − REVISED JULY 2002
electrical characteristics over recommended operating free-air temperature range (unless
otherwise noted) (continued)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
bq2057 and bq2057C,
High-side current sensing configuration
95.4
105
115.5
bq2057T and bq2057W,
High-side current sensing configuration
113.6
125
137.5
bq2057 and bq2057C,
Low-side current sensing configuration
100
110
121
bq2057T and bq2057W,
Low-side current sensing configuration
118.1
130
143
−24
−14
−4
29.1
30
30.9
58.3
60
61.8
bq2057
2.94
3
3.06
bq2057C
3.04
3.1
3.16
bq2057T
5.98
6.1
6.22
bq2057W
6.18
6.3
6.43
UNIT
CURRENT REGULATION
V(SNS)
Current regulation
threshold
mV
CHARGE TERMINATION DETECTION
I(TERM)
Charge termination
current detect
threshold
Voltage at pin SNS, relative to VCC for high-side
sensing, and to Vss for low-side sensing,
0°C ≤ TA ≤ 50°C
mV
TEMPERATURE COMPARATOR
V(TS1)
V(TS2)
Lower temperature
threshold
Upper temperature
threshold
TS pin voltage
%VCC
PRECHARGE COMPARATOR
V(min)
Precharge
threshold
V
PRECHARGE CURRENT REGULATION
I(PRECHG)
Precharge current
regulation
Voltage at pin SNS, relative to VCC for high-side
sensing, and to VSS for low-side sensing,
0°C ≤ TA ≤ 50°C
Voltage at pin SNS, relative to VCC for high-side
sensing, 0°C ≤ TA ≤ 50°C, VCC = 5 V
13
mV
3
13
22
bq2057 and bq2057C
VO(REG)−
98 mV
VO(REG)−
100 mV
VO(REG)−
102 mV
bq2057T and bq2057W
VO(REG)−
196 mV
VO(REG)−
200 mV
VO(REG)−
204 mV
V(BAT)+0.3 V ≤ VCC ≤ VCC(max), bq2057, bq2057C,
bq2057T, bq2057W
1.87
2.2
2.53
V(BAT)+0.3 V ≤ VCC ≤ VCC(max), bq2057T and
bq2057W in low-side sensing configuration
2.09
2.4
2.76
mV
VRCH COMPARATOR (Battery Recharge Threshold)
V(RCH)
Recharge
threshold
V
CHARGE-RATE COMPENSATION (AutoComp)
G(COMP)
AutoComp gain
V/V
STAT PIN
VOL(STAT)
Output (low)
voltage
IOL = 10 mA
VOH(STAT)
Output (high)
voltage
IOH = 5 mA
0.7
V
VCC-0.5
CC PIN
VOL(CC)
IO(CC)
6
Output low voltage
Sink current
IO(CC) = 5 mA (sink)
Not to exceed power rating specification (PD)
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5
1.5
V
40
mA
SLUS025F − MAY 2001 − REVISED JULY 2002
APPLICATION INFORMATION
RSNS
0.2 Ω
Q1
FZT788B
PACK+
DC+
C1
0.1 µF
VCC
R1
1 kΩ
PACK−
NTC
VCC
bq2057
CC
C2
0.1 µF
COMP
SNS
BAT
VCC
TS
VSS
STAT
RT1
TEMP
D1
GND
RT2
Battery
Pack
R2
2 kΩ
Figure 1. Low Dropout Single- or Two-Cell Li-Ion/Li-Pol Charger
functional description
The bq2057 is an advanced linear charge controller for single or two-cell Li-Ion or Li-Pol applications. Figure 1
shows the schematic of charger using a PNP pass transistor. Figure 2 is an operational state diagram, and
Figure 3 is a typical charge profile. Figure 4 shows the schematic of a charger using P-channel MOSFET.
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7
SLUS025F − MAY 2001 − REVISED JULY 2002
APPLICATION INFORMATION
POR
Sleep Mode
VCC > V(BAT)
Checked at All
Times
Indicate SLEEP
MODE
(STAT = Hi-Z)
No
Yes
Suspend Charge
TS Pin
in TS1 to TS2
Range
Indicate CHARGE
SUSPEND
(STAT = Hi-Z)
No
Yes
Regulate
I(PRECHG)
V(BAT) <V(min)
Indicate
Charge In-Progress
(STAT = High)
Yes
Suspend Charge
No
TS Pin
in TS1 to TS2
Range
Regulate
Current or Voltage
No
Indicate
Charge In-Progress
(STAT = High)
Indicate CHARGE
SUSPEND
(STAT = Hi-Z)
Yes
No
Suspend Charge
No
TS Pin
in TS1 to TS2
Range
TS Pin
in TS1 to TS2
Range
V(BAT) < V(min)
Indicate CHARGE
SUSPEND
(STAT = Hi-Z)
No
Yes
Yes
Yes
TS Pin
in TS1 to TS2
Range
No
V(BAT) < V(min)
Yes
No
Terminate Charge
Yes
I(TERM)
Detected
Yes
Indicate CHARGE
Done
(STAT = Low)
V(BAT) < V(RCH)
Yes
Figure 2. Operation Flowchart
8
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No
SLUS025F − MAY 2001 − REVISED JULY 2002
APPLICATION INFORMATION
Preconditioning
Phase
Current Regulation
Phase
Voltage Regulation and Charge
Termination Phase
Regulation Voltage
Regulation Current
Minimum Charge
Voltage
Preconditioning
and Taper Detect
Figure 3. Typical Charge Profile
qualification and precharge
When power is applied, the bq2057 starts a charge-cycle if a battery is already present or when a battery is
inserted. Charge qualification is based on battery temperature and voltage. The bq2057 suspends charge if the
battery temperature is outside the V(TS1) to V(TS2) range and suspends charge until the battery temperature is
within the allowed range. The bq2057 also checks the battery voltage. If the battery voltage is below the
precharge threshold V(min), the bq2057 uses precharge to condition the battery. The conditioning charge rate
I(PRECHG) is set at approximately 10% of the regulation current. The conditioning current also minimizes heat
dissipation in the external pass-element during the initial stage of charge. See Figure 3 for a typical
charge-profile.
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9
SLUS025F − MAY 2001 − REVISED JULY 2002
APPLICATION INFORMATION
D1
Q1
SI6475DQ
RSNS
0.2 Ω
PACK+
DC+
Battery
Pack
C2
0.1 µF
R2
1 kΩ
PACK−
NTC
U1
bq2057
CC
RT1
COMP
SNS
BAT
VCC
TS
VSS
STAT
TEMP
R4
RT2
511 Ω
C1
0.1 µF
U2
R5
1 kΩ
R3
1 kΩ
CMD67−
22SRUC
GND
Figure 4. 0.5-A Charger Using P-Channel MOSFET
current regulation phase
The bq2057 regulates current while the battery-pack voltage is less than the regulation voltage, VO(REG). The
bq2057 monitors charge current at the SNS input by the voltage drop across a sense-resistor, RSNS, in series
with the battery pack. In high-side current sensing configuration (Figure 5), RSNS is between the VCC and SNS
pins, and in low-side sensing (Figure 6) the RSNS is between VSS (battery negative) and SNS (charger ground)
pins. Charge-current feedback, applied through pin SNS, maintains a voltage of V(SNS) across the current sense
resistor. The following formula calculates the value of the sense resistor:
V
R
SNS
+
I
(1)
(SNS)
O(REG)
Where IO(REG) is the desired charging current.
10
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SLUS025F − MAY 2001 − REVISED JULY 2002
APPLICATION INFORMATION
DC+
DC+
RSNS
BAT+
BAT+
bq2057
bq2057
SNS
COMP
BAT
CC
VCC
VSS
TS
SNS
COMP
BAT
CC
VCC
VSS
TS
STAT
BAT−
DC−
STAT
DC−
RSNS
BAT−
Figure 5. High-Side Current Sensing
Figure 6. Low-Side Current Sensing
voltage regulation phase
The voltage regulation feedback is through the BAT pin. This input is tied directly to the positive side of the
battery pack. The bq2057 monitors the battery-pack voltage between the BAT and VSS pins. The bq2057 is
offered in four fixed-voltage versions: 4.1 V, 4.2 V, 8.2 V and 8.4 V.
Other regulation voltages can be achieved by adding a voltage divider between the positive and negative
terminals of the battery pack and using bq2057T or bq2057W. The voltage divider presents scaled battery-pack
voltage to BAT input. (See Figure 7 and Figure 8.) The resistor values RB1 and RB2 for the voltage divider are
calculated by the following equation:
R
R
B1 +
B2
ǒ
V
N
V
(CELL)
O(REG)
Ǔ
(2)
–1
Where:
N = Number of cells in series
V(CELL) = Desired regulation voltage per cell
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11
SLUS025F − MAY 2001 − REVISED JULY 2002
APPLICATION INFORMATION
DC+
DC+
BAT+
RSNS
BAT+
RB1
bq2057
RB1
bq2057
SNS
COMP
BAT
CC
VCC
VSS
TS
RB2
BAT−
STAT
SNS
COMP
BAT
CC
VCC
VSS
TS
STAT
DC−
RB2
BAT−
RSNS
DC−
Figure 7. Optional Voltage Divider for
Nonstandard Regulation Voltage,
(High-Side Current Sensing)
Figure 8. Optional Voltage Divider for
Nonstandard Regulation Voltage,
(Low-Side Current Sensing)
charge termination and recharge
The bq2057 monitors the charging current during the voltage-regulation phase. The bq2057 declares a done
condition and terminates charge when the current tapers off to the charge termination threshold, I(TERM). A new
charge cycle begins when the battery voltage falls below the V(RCH) threshold.
battery temperature monitoring
The bq2057 continuously monitors temperature by measuring the voltage between the TS and VSS pins. A
negative- or a positive-temperature coefficient thermistor (NTC, PTC) and an external voltage divider typically
develop this voltage. (See Figure 9.) The bq2057 compares this voltage against its internal V(TS1) and V(TS2)
thresholds to determine if charging is allowed. (See Figure 10.) The temperature sensing circuit is immune to
any fluctuation in VCC, since both the external voltage divider and the internal thresholds (V(TS1) and V(TS2))
are referenced to VCC.
The resistor values of R(T1) and R(T2) are calculated by the following equations:
For NTC Thermistors
R
R
12
T1
+
T2
+
5
3
R
(3)
TC
ǒRTC * RTHǓ
5
ƪǒ2
R
TH
R
R
TH
Ǔ–ǒ7
TC
R
TC
R
(4)
Ǔƫ
TH
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SLUS025F − MAY 2001 − REVISED JULY 2002
APPLICATION INFORMATION
battery temperature monitoring (continued)
For PTC Thermistors
R
R
T1
+
T2
+
5
R
R
TH
(5)
TC
ǒRTH * RTCǓ
3
5
ƪǒ2
R
R
TH
R
Ǔ–ǒ7
TH
TC
R
(6)
Ǔƫ
TC
Where R(TC) is the cold temperature resistance and R(TH) is the hot temperature resistance of thermistor, as
specified by the thermistor manufacturer.
RT1 or RT2 can be omitted If only one temperature (hot or cold) setting is required. Applying a voltage between
the V(TS1) and V(TS2) thresholds to pin TS disables the temperature-sensing feature.
DC+
DC+
RSNS
BAT+
BAT+
bq2057
RT1
SNS
DC−
bq2057
COMP
SNS
BAT
CC
BAT
CC
VCC
VSS
VCC
VSS
TS
TS
STAT
COMP
STAT
RT1
DC−
RT2
Thermistor
RT2
BAT−
BAT−
Thermistor
RSNS
High-Side Current Sensing
Low-Side Current Sensing
Figure 9. Temperature Sensing Circuits
VCC
Temperature Fault
V(TS2)
Normal Temperature Range
V(TS1)
Temperature Fault
VSS
Figure 10. bq2057 TS Input Thresholds
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13
SLUS025F − MAY 2001 − REVISED JULY 2002
APPLICATION INFORMATION
charge inhibit function
The TS pin can be used as charge-inhibit input. The user can inhibit charge by connecting the TS pin to VCC
or VSS (or any level outside the V(TS1) to V(TS2) thresholds). Applying a voltage between the V(TS1) and V(TS2)
thresholds to pin TS returns the charger to normal operation.
charge status indication
The bq2057 reports the status of the charger on the 3-state STAT pin. The following table summarized the
operation of the STAT pin.
CONDITION
STAT PIN
Battery conditioning and charging
High
Charge complete (Done)
Low
Temperature fault or sleep mode
Hi-Z
The STAT pin can be used to drive a single LED (Figure 1), dual-chip LEDs (Figure 4) or for interface to a host
or system processor (Figure 11). When interfacing the bq2057 to a processor, the user can use an output port,
as shown in Figure 11, to recognize the high-Z state of the STAT pin. In this configuration, the user needs to
read the input pin, toggle the output port and read the STAT pin again. In a high-Z condition, the input port always
matches the signal level on the output port.
Host
Processor
bq2057CTS
SNS
COMP
BAT
CC
VCC
VSS
TS
OUT
IN
STAT
Figure 11. Interfacing the bq2057 to a Host Processor
low-power sleep mode
The bq2057 enters the sleep mode if the VCC falls below the voltage at the BAT input. This feature prevents
draining the battery pack during the absence of VCC.
14
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SLUS025F − MAY 2001 − REVISED JULY 2002
APPLICATION INFORMATION
selecting an external pass-transistor
The bq2057 is designed to work with both PNP transistor and P-channel MOSFET. The device should be chosen
to handle the required power dissipation, given the circuit parameters, PCB layout and heat sink configuration.
The following examples illustrate the design process for either device:
PNP transistor:
Selection steps for a PNP bipolar transistor: Example: VI = 4.5 V, I(REG) = 1 A, 4.2-V single-cell Li-Ion (bq2057C).
VI is the input voltage to the charger and I(REG) is the desired charge current (see Figure 1).
1. Determine the maximum power dissipation, PD, in the transistor.
The worst case power dissipation happens when the cell voltage, V(BAT), is at its lowest (typically 3 V at the
beginning of current regulation phase) and VI is at its maximum.
Where VCS is the voltage drop across the current sense resistor.
PD = (VI − VCS – V (BAT)) × IREG
PD = (4.5 – 0.1 − 3) × 1 A
PD= 1.4 W
(7)
2. Determine the package size needed in order to keep the junction temperature below the manufacturer’s
recommended value, T(J)max. Calculate the total theta, θ(°C/W), needed.
θ
JC
+
ǒT(J)max * TA(max)Ǔ
P
(8)
D
(150–40)
θ
+
JC
1.4
θ
JC
+ 78°CńW
Now choose a device package with a theta at least 10% below this value to account for additional thetas
other than the device. A SOT223 package, for instance, has typically a theta of 60°C/W.
3. Select a collector-emitter voltage, V(CE), rating greater than the maximum input voltage. A 15-V device will
be adequate in this example.
4. Select a device that has at least 50% higher drain current IC rating than the desired charge current I(REG).
5. Using the following equation, calculate the minimum beta (β or hFE) needed:
b
(9)
I
+ CMAX
min
I
B
1
0.035
b
min
+
b
min
+ 28
where Imax(C)) is the maximum collector current (in this case same as I(REG)), and IB is the base current
(chosen to be 35 mA in this example).
NOTE:
The beta of a transistor drops off by a factor of 3 over temperature and also drops off with load.
Therefore, note the beta of device at I(REG) and the minimum ambient temperature when choosing
the device. This beta should be larger than the minimum required beta.
Now choose a PNP transistor that is rated for V(CE) ≥15 V, θJC ≤ 78°C/W, IC ≥ 1.5 A, βmin ≥ 28 and that is in a
SOT223 package.
www.ti.com
15
SLUS025F − MAY 2001 − REVISED JULY 2002
APPLICATION INFORMATION
selecting an external pass-transistor (continued)
P-channel MOSFET:
Selection steps for a P-channel MOSFET: Example: VI = 5.5 V, I(REG) = 500 mA, 4.2-V single-cell Li−Ion
(bq2057C). VI is the input voltage to the charger and I(REG) is the desired charge current. (See Figure 4.)
1. Determine the maximum power dissipation, PD, in the transistor.
The worst case power dissipation happens when the cell voltage, V(BAT), is at its lowest (typically 3 V at
the beginning of current regulation phase) and VI is at its maximum.
Where VD is the forward voltage drop across the reverse-blocking diode (if one is used), and VCS is the
voltage drop across the current sense resistor.
PD = (VI – VD − V(CS) – V(BAT)) × I(REG)
PD = (5.5 – 0.4 – 0.1 −3) × 0.5 A
PD = 1 W
(10)
2. Determine the package size needed in order to keep the junction temperature below the manufacturer’s
recommended value, TJMAX. Calculate the total theta, θ(°C/W), needed.
θ
JC
+
ǒTmax(J)–TA(max)Ǔ
P
(11)
D
(150–40)
θ
+
JC
1
θ
JC
+ 110°CńW
Now choose a device package with a theta at least 10% below this value to account for additional thetas
other than the device. A TSSOP-8 package, for instance, has typically a theta of 70°C/W.
3. Select a drain-source voltage, V(DS), rating greater than the maximum input voltage. A 12 V device will be
adequate in this example.
4. Select a device that has at least 50% higher drain current (ID) rating than the desired charge current I(REG).
5. Verify that the available drive is large enough to supply the desired charge current.
V(GS) = (VD +V(CS) + VOL(CC)) − VI
V(GS) = (0.4 + 0.1 + 1.5) – 5.5
V(GS) = −3.5
(12)
Where V(GS) is the gate-to-source voltage, VD is the forward voltage drop across the reverse-blocking diode
(if one is used), and VCS is the voltage drop across the current sense resistor, and VOL(CC) is the CC pin
output low voltage specification for the bq2057.
Select a MOSFET with gate threshold voltage, V(GSth), rating less than the calculated V(GS).
Now choose a P-channel MOSFET transistor that is rated for VDS ≤ −15 V, θJC ≤ 110°C/W, ID ≥ 1 A,
V(GSth) ≥ −3.5 V and in a TSSOP package.
16
www.ti.com
SLUS025F − MAY 2001 − REVISED JULY 2002
APPLICATION INFORMATION
selecting input capacitor
In most applications, all that is needed is a high-frequency decoupling capacitor. A 0.1 µF ceramic, placed in
proximity to VCC and VSS pins, works well. The bq2057 works with both regulated and unregulated external
dc supplies. If a non-regulated supply is chosen, the supply unit should have enough capacitance to hold up
the supply voltage to the minimum required input voltage at maximum load. If not, more capacitance must be
added to the input of the charger.
selecting output capacitor
The bq2057 does not require any output capacitor for loop stability. The user can add output capacitance in order
to control the output voltage when a battery is not present. The charger quickly charges the output capacitor
to the regulation voltage, but the output voltage decays slowly, because of the low leakage current on the BAT
pin, down to the recharge threshold. Addition of a 0.1µF ceramic capacitor, for instance, results in a 100 mV(pp)
ripple waveform, with an approximate frequency of 25Hz. Higher capacitor values can be used if a lower
frequency is desired.
automatic charge-rate compensation
To reduce charging time, the bq2057 uses the proprietary AutoComp technique to compensate safely for
internal impedance of the battery pack. The AutoComp feature is disabled by connecting the COMP pin to VCC
in high-side current-sensing configuration, and to VSS in low-side current-sensing configuration. The COMP
pin must not be left floating.
Figure 12 outlines the major components of a single-cell Li-Ion battery pack. The Li-Ion battery pack consists
of a cell, protection circuit, fuse, connector, current sense-resistors, and some wiring. Each of these components
contains some resistance. Total impedance of the battery pack is the sum of the minimum resistances of all
battery-pack components. Using the minimum resistance values reduces the odds for overcompensating.
Overcompensating may activate the safety circuit of the battery pack.
BAT+
Terminal
Wire
Fuse
Cell
Protection
Controller
BAT−
Terminal
Wire
Wire
Discharge
Wire
Charge
Figure 12. Typical Components of a Single-Cell Li-Ion Pack
Compensation is achieved through input pin COMP (Figure 13). A portion of the current-sense voltage,
presented through this pin, is scaled by a factor of G(COMP) and summed with the regulation threshold, VO(REG).
This process increases the output voltage to compensate for the battery pack’s internal impedance and for
undesired voltage drops in the circuit.
www.ti.com
17
SLUS025F − MAY 2001 − REVISED JULY 2002
APPLICATION INFORMATION
automatic charge-rate compensation (continued)
AutoComp setup requires the following information:
D Total impedance of battery pack (Z(PACK))
D Maximum charging current (I(REG))
The voltage drop across the internal impedance of battery pack, V(Z), can then be calculated using the following
equation:
V(Z) = Z(PACK) × I(REG)
(13)
The required compensation is then calculated using the following equations:
V
V
(COMP)
V
(PACK)
+
G
+V
(14)
(Z)
(COMP)
O(REG)
ǒ
) G
(COMP)
V
Ǔ
(COMP
Where V(COMP) is the voltage on COMP pin. This voltage is referenced to VCC in high-side current sensing
configuration and to VSS for low-side sensing. V(PACK) is the voltage across the battery pack.
The values of R(COMP1) and R(COMP2) can be calculated using the following equation:
(15)
V
R
(COMP)
COMP2
+
R
)R
V
COMP1
COMP2
(SNS)
BAT+
DC+
DC+
RCOMP2
BAT+
RCOMP1
bq2057
DC−
SNS
bq2057
RSNS
COMP
SNS
COMP
BAT
CC
BAT
CC
VCC
VSS
VCC
VSS
TS
TS
STAT
STAT
DC−
RCOMP2
RSNS
RCOMP1
BAT−
High-Side Current Sensing
Low-Side Current Sensing
Figure 13. AutoComp Circuits
18
www.ti.com
SLUS025F − MAY 2001 − REVISED JULY 2002
APPLICATION INFORMATION
automatic charge-rate compensation (continued)
The following example illustrates these calculations:
Assume Z(PACK) = 100 mΩ, I(REG) = 500 mA, high-side current sensing bq2057C
V
(Z)
+Z
I
(PACK)
(16)
(REG)
+ 0.1 0.5
(Z)
V(Z) = 50 mV
V
V
V
V
(COMP)
+
(COMP)
+ 0.05
2.2
G
(17)
(Z)
(COMP)
V(COMP) = 22.7 mV
Let RCOMP2 = 10 kΩ
R
R
COMP1
R
+
COMP1
R
COMP1
COMP2
+ 10k
ǒV(SNS) * V(COMP)Ǔ
V
(18)
(COMP)
(105 mV * 22.7 mV)
22.7 mV
+ 36.25 kW
Use the closest standard value (36.0 kΩ) for RCOMP1
www.ti.com
19
SLUS025F − MAY 2001 − REVISED JULY 2002
MECHANICAL DATA
DGK (R-PDSO-G8)
PLASTIC SMALL-OUTLINE PACKAGE
0,38
0,25
0,65
8
0,25 M
5
0,15 NOM
3,05
2,95
4,98
4,78
Gage Plane
0,25
1
0°−ā 6°
4
3,05
2,95
0,69
0,41
Seating Plane
1,07 MAX
0,15
0,05
0,10
4073329/B 04/98
NOTES: A.
B.
C.
D.
20
All linear dimensions are in millimeters.
This drawing is subject to change without notice.
Body dimensions do not include mold flash or protrusion.
Falls within JEDEC MO-187
www.ti.com
SLUS025F − MAY 2001 − REVISED JULY 2002
MECHANICAL DATA
8−Pin SOIC
Narrow (SN)
8−Pin SN ( 0.150” SOIC )
Inches
Dimension
A
Millimeters
Min.
Max.
Min.
Max.
0.060
0.070
1.52
1.78
A1
0.004
0.010
0.10
0.25
B
0.013
0.020
0.33
0.51
C
0.007
0.010
0.18
0.25
D
0.185
0.200
4.70
5.08
E
0.150
0.160
3.81
4.06
e
0.045
0.055
1.14
1.40
H
0.225
0.245
5.72
6.22
L
0.015
0.035
0.38
0.89
TS: 8−Pin TSSOP
Inches
Dimension
Millimeters
Min.
Max.
Min.
Max.
A
-
0.043
-
1.10
A1
0.002
0.006
0.05
0.15
B
0.007
0.012
0.18
0.30
C
0.004
0.007
0.09
0.18
D
0.1 14
0.122
2.90
3.10
E
0.169
0.176
4.30
4.48
e
H
0.0256BSC
0.246
0.256
0.65BSC
6.25
6.50
Notes:
1. Controlling dimension: millimeters. Inches shown for reference only.
2
’D’ and ’E’ do not include mold flash or protrusions. Mold flash or protrusions shall not exceed 0,15 mm per side
3
Each lead centerline shall be located within ±0,10 mm of its exact true position.
4
Leads shall be coplanar within 0,08 mm at the seating plane.
5
Dimension ’B’ does not include dambar protrusion. The dambar protrusion(s) shall not cause the lead width
to exceed ’B’ maximum by more than 0,08 mm.
6
Dimension applies to the flat section of the lead between 0,10 mm and 0,25 mm from the lead tip.
7
’A1’ is defined as the distance from the seating plane to the lowest point of the package body (base plane).
www.ti.com
21
PACKAGE OPTION ADDENDUM
www.ti.com
4-Mar-2005
PACKAGING INFORMATION
Orderable Device
Status (1)
Package
Type
Package
Drawing
Pins Package Eco Plan (2)
Qty
Lead/Ball Finish
MSL Peak Temp (3)
BQ2057CDGK
ACTIVE
MSOP
DGK
8
80
None
CU NIPDAU
Level-1-220C-UNLIM
BQ2057CDGKR
ACTIVE
MSOP
DGK
8
2500
None
CU NIPDAU
Level-1-220C-UNLIM
BQ2057CSN
ACTIVE
SOIC
D
8
75
None
CU SNPB
Level-1-220C-UNLIM
BQ2057CSNTR
ACTIVE
SOIC
D
8
2500
None
CU SNPB
Level-1-220C-UNLIM
BQ2057CTS
ACTIVE
TSSOP
PW
8
150
None
CU NIPDAU
Level-1-220C-UNLIM
BQ2057CTSTR
ACTIVE
TSSOP
PW
8
2000
None
CU NIPDAU
Level-1-220C-UNLIM
BQ2057DGK
ACTIVE
MSOP
DGK
8
80
None
CU NIPDAU
Level-1-220C-UNLIM
BQ2057DGKR
ACTIVE
MSOP
DGK
8
2500
None
CU NIPDAU
Level-1-220C-UNLIM
BQ2057PDGK
ACTIVE
MSOP
DGK
8
80
None
CU NIPDAU
Level-1-220C-UNLIM
BQ2057PDGKR
ACTIVE
MSOP
DGK
8
2500
None
CU NIPDAU
Level-1-220C-UNLIM
BQ2057SN
ACTIVE
SOIC
D
8
75
None
CU SNPB
Level-1-220C-UNLIM
BQ2057SNTR
ACTIVE
SOIC
D
8
2500
None
CU SNPB
Level-1-220C-UNLIM
BQ2057TS
ACTIVE
TSSOP
PW
8
150
None
CU NIPDAU
Level-1-220C-UNLIM
BQ2057TSN
ACTIVE
SOIC
D
8
75
None
CU SNPB
Level-1-220C-UNLIM
BQ2057TSNTR
ACTIVE
SOIC
D
8
2500
None
CU SNPB
Level-1-220C-UNLIM
BQ2057TSTR
ACTIVE
TSSOP
PW
8
2000
None
CU NIPDAU
Level-1-220C-UNLIM
BQ2057TTS
ACTIVE
TSSOP
PW
8
150
None
CU NIPDAU
Level-1-220C-UNLIM
BQ2057TTSTR
ACTIVE
TSSOP
PW
8
2000
None
CU NIPDAU
Level-1-220C-UNLIM
BQ2057WSN
ACTIVE
SOIC
D
8
75
None
CU SNPB
Level-1-220C-UNLIM
BQ2057WSNTR
ACTIVE
SOIC
D
8
2500
None
CU SNPB
Level-1-220C-UNLIM
BQ2057WTS
ACTIVE
TSSOP
PW
8
150
None
CU NIPDAU
Level-1-220C-UNLIM
BQ2057WTSTR
ACTIVE
TSSOP
PW
8
2000
None
CU NIPDAU
Level-1-220C-UNLIM
(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 - May not be currently available - please check http://www.ti.com/productcontent for the latest availability information and additional
product content details.
None: Not yet available Lead (Pb-Free).
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.
Green (RoHS & no Sb/Br): TI defines "Green" to mean "Pb-Free" and in addition, uses package materials that do not contain halogens,
including bromine (Br) or antimony (Sb) above 0.1% of total product weight.
(3)
MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDECindustry standard classifications, and peak solder
temperature.
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.
Addendum-Page 1
PACKAGE OPTION ADDENDUM
www.ti.com
4-Mar-2005
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 2
IMPORTANT NOTICE
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enhancements, improvements, and other changes to its products and services at any time and to discontinue
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