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      
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FEATURES
DIdeal for Single (4.1 V or 4.2 V) and Dual-Cell
(8.2 V or 8.4 V) Li-Ion or Li-Pol Packs
DRequires Small Number of External
Components
D0.3 V Dropout Voltage for Minimizing Heat
Dissipation
DBetter Than ±1% Voltage Regulation Accuracy
With Preset Voltages
DAutoCompt Dynamic Compensation of
Battery Pack’s Internal Impedance to Reduce
Charge Time
DOptional Cell-Temperature Monitoring Before
and During Charge
DIntegrated Voltage and Current Regulation
With Programmable Charge-Current and High-
or Low-Side Current Sensing
DIntegrated Cell Conditioning for Reviving
Deeply Discharged Cells and Minimizing Heat
Dissipation During Initial Stage Of Charge
DCharge Status Output for Single or Dual Led
or Host Processor Interface
DAutomatic Battery-Recharge Feature
DCharge Termination by Minimum Current
DAutomatic Low-Power Sleep Mode When VCC
Is Removed
DEVMs Available for Quick Evaluation
DPackaging: 8-Pin SOIC, 8-Pin TSSOP, 8-Pin
MSOP
DESCRIPTION
The BENCHMARQ bq2057 series advanced
Lithium-Ion (Li-Ion) and Lithium-Polymer (Li-Pol) linear
charge-management ICs are designed for cost-
sensitive 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 pass-
element during the initial stage of the charge. After
conditioning, the bq2057 applies a constant current to
the battery. A n 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.
COMP
CC
VSS
STAT
8
7
6
5
1
2
3
4
SNS
BAT
VCC
TS
bq2057xSN or bq2057xTS
SOIC (SN) or TSSOP (TS) PACKAGE
(TOP VIEW)
BAT
SNS
COMP
CC
8
7
6
5
1
2
3
4
VCC
TS
STAT
VSS
bq2057xDGK
MSOP (DGK) PACKAGE
(TOP VIEW)
  !"#$%! & '("")% $& ! *(+'$%! ,$%)-
"!,('%& '!!"# %! &*)''$%!& *)" %.) %)"#& ! )/$& &%"(#)%&
&%$,$", 0$""$%1- "!,('%! *"!')&&2 ,!)& !% )')&&$"+1 '+(,)
%)&%2 ! $++ *$"$#)%)"&-
AutoComp is a trademark of Texas Instruments.
Copyright 2002, Texas Instruments Incorporated
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.
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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
TACHARGE REGULATION
VOLTAGE SOIC
(SN) TSSOP
(TS) MSOP
(DGK)
4.1 V Not available bq2057TS bq2057DGK
−20°C to 70°C
4.2 V bq2057CSN bq2057CTS bq2057CDGK
−20°C to 70°C8.2 V Not available bq2057TTS
Not available
8.4 V bq2057WSN bq2057WTS Not available
Note the difference in pinout for this package.
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function block diagram
_
+
Sleep Mode
_
+
VCC
DONE
V-Control
I-Control
_
+
Voltage Regulation
Internal Reference
_
+
Battery
Recharge
Battery
Conditioning
_
+
_
+
VCC
TS2 Trip
TS1 Trip
_
+
_
+
Current Regulation
_
+
Charge Termination
High/Low SNS Set
VCC−V(SNS)
VSS−V(SNS)
VCC
0.5 VCC
I-Control
Control
Block
G(comp)
BAT
COMP
TS
SNS
CC
STAT
VSS
VCC
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Terminal Functions
TERMINAL
NO.
I/O
DESCRIPTION
NAME SOIC (SN) and
TSSOP (TS) MSOP
(DGK)
I/O
DESCRIPTION
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.
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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 PD20 mA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Source current (STAT pin) not to exceed PD10 mA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Output current (CC pin) not to exceed PD40 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 DERATING FACTOR
ABOVE TA = 25°CTA 25°C
POWER RATING TA = 70°C
POWER RATING
DGK 3.4 mW/°C424 mW 271 mW
recommended operating conditions
MIN MAX UNIT
Supply voltage, VCC 4.5 15 V
Operating free-air temperature range, TA−20 70 °C
electrical characteristics over recommended operating free-air temperature range (unless
otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
I(VCC) VCC Current VCC > VCC(min), Excluding external loads 2 4 mA
I(VCCS)
VCC Sleep current
For bq2057 and bq2957C,
V(BAT) V(min), V(BAT) – VCC 0.8 V 3 6
A
I(VCCS) VCC Sleep current For bq2057T and bq2957W,
V(BAT) V(min), V(BAT) – VCC 0.8 V 10 µA
IIB(BAT) Input bias current on BAT pin V(BAT) = V(REG) 1µA
IIB(SNS) Input bias current on SNS pin V(SNS)= 5 V 5µA
IIB(TS) Input bias current on TS pin V(TS) = 5 V 5µA
IIB(COMP) Input bias current on COMP pin V(COMP) = 5 V 5µA
BATTERY VOLTAGE REGULATION
bq2057, See Notes 1, 2, 3 4.059 4.10 4.141
VO(REG)
Output voltage
bq2057C, See Notes 1, 2, 3 4.158 4.20 4.242
V
VO(REG) Output voltage bq2057T, See Notes 1, 2, 3 8.119 8.20 8.282 V
bq2057W, See Notes 1, 2, 3 8.317 8.40 8.484
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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electrical characteristics over recommended operating free-air temperature range (unless
otherwise noted) (continued)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
CURRENT REGULATION
bq2057 and bq2057C,
High-side current sensing configuration 95.4 105 115.5
V(SNS)
Current regulation
bq2057T and bq2057W,
High-side current sensing configuration 113.6 125 137.5
V(SNS)
Current regulation
threshold bq2057 and bq2057C,
Low-side current sensing configuration 100 110 121 mV
bq2057T and bq2057W,
Low-side current sensing configuration 118.1 130 143
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−24 −14 −4 mV
TEMPERATURE COMPARATOR
V(TS1) Lower temperature
threshold
TS pin voltage
29.1 30 30.9
V(TS2) Upper temperature
threshold
TS pin voltage 58.3 60 61.8 %VCC
PRECHARGE COMPARATOR
bq2057 2.94 3 3.06
V(min)
Precharge
bq2057C 3.04 3.1 3.16
V(min)
Precharge
threshold bq2057T 5.98 6.1 6.22 V
threshold
bq2057W 6.18 6.3 6.43
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°C13 mV
I(PRECHG)
regulation
Voltage at pin SNS, relative to VCC for high-side
sensing, 0°C TA 50°C, VCC = 5 V 3 13 22 mV
VRCH COMPARATOR (Battery Recharge Threshold)
V(RCH)
Recharge
bq2057 and bq2057C VO(REG)
98 mV VO(REG)
100 mV VO(REG)
102 mV
V(RCH)
Recharge
threshold bq2057T and bq2057W VO(REG)
196 mV VO(REG)
200 mV VO(REG)
204 mV
V
CHARGE-RATE COMPENSATION (AutoComp)
G(COMP)
AutoComp gain
V(BAT)+0.3 V VCC VCC(max), bq2057, bq2057C,
bq2057T, bq2057W 1.87 2.2 2.53
G(COMP) AutoComp gain V(BAT)+0.3 V VCC VCC(max), bq2057T and
bq2057W in low-side sensing configuration 2.09 2.4 2.76 V/V
STAT PIN
VOL(STAT) Output (low)
voltage IOL = 10 mA 0.7
VOH(STAT) Output (high)
voltage IOH = 5 mA VCC-0.5 V
CC PIN
VOL(CC) Output low voltage IO(CC) = 5 mA (sink) 1.5 V
IO(CC) Sink current Not to exceed power rating specification (PD) 5 40 mA
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APPLICATION INFORMATION
CC
SNS
VCC
VSS
COMP
BAT
TS
STAT
bq2057
VCC
R1
1 k
D1
R2
2 k
RT2
RT1
VCC
TEMP
PACK−
PACK+
C1
0.1 µF
NTC
Battery
Pack
C2
0.1 µF
DC+
GND
RSNS
0.2
Q1
FZT788B
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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APPLICATION INFORMATION
Regulate
Current or Voltage
POR
VCC > V(BAT)
Checked at All
Times
Sleep Mode
No
TS Pin
in TS1 to TS2
Range
Yes
No
Suspend Charge
Indicate SLEEP
MODE
(STAT = Hi-Z)
Yes
Indicate CHARGE
SUSPEND
(STAT = Hi-Z)
V(BAT) < V(min)
Regulate
I(PRECHG)
Indicate
Charge In-Progress
(STAT = High)
Yes
TS Pin
in TS1 to TS2
Range
Suspend Charge
Indicate CHARGE
SUSPEND
(STAT = Hi-Z)
No
Yes
TS Pin
in TS1 to TS2
Range
No
V(BAT) < V(min)
No
Yes
Indicate
Charge In-Progress
(STAT = High)
Suspend Charge
Indicate CHARGE
SUSPEND
(STAT = Hi-Z)
TS Pin
in TS1 to TS2
Range
No
No
Yes
Yes No
TS Pin
in TS1 to TS2
Range
V(BAT) < V(min)
No
V(BAT) < V(RCH)
Yes
Yes
Yes
Yes
I(TERM)
Detected
Terminate Charge
Indicate CHARGE
Done
(STAT = Low)
No
Figure 2. Operation Flowchart
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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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APPLICATION INFORMATION
CC
SNS
VCC
VSS
COMP
BAT
TS
STAT
bq2057
D1
U2
R3
1 k
RT2
RT1
TEMP
PACK−
PACK+
C2
0.1 µF
NTC
Battery
Pack
DC+
RSNS
0.2
CMD67−
22SRUC
R5
1 k
R2
1 k
R4
511
C1
0.1 µF
Q1
SI6475DQ
GND
U1
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:
RSNS +V(SNS)
IO(REG)
Where IO(REG) is the desired charging current.
(1)
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APPLICATION INFORMATION
Figure 5. High-Side Current Sensing Figure 6. Low-Side Current Sensing
SNS
BAT
VCC
TS
COMP
CC
VSS
STAT
bq2057
DC+
DC−
RSNS BAT+
BAT−
SNS
BAT
VCC
TS
COMP
CC
VSS
STAT
bq2057
DC+
DC− RSNS
BAT+
BAT−
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 B AT input. (See Figure 7 and Figure 8.) The resistor values RB1 and RB2 for the voltage divider are
calculated by the following equation:
RB1
RB2 +ǒN V(CELL)
VO(REG)Ǔ–1
Where:
N = Number of cells in series
V(CELL) = Desired regulation voltage per cell
(2)
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APPLICATION INFORMATION
Figure 7. Optional Voltage Divider for
Nonstandard Regulation Voltage,
(High-Side Current Sensing)
SNS
BAT
VCC
TS
COMP
CC
VSS
STAT
bq2057
DC+
DC−
BAT+
BAT−
RSNS
RB1
RB2
SNS
BAT
VCC
TS
COMP
CC
VSS
STAT
bq2057
DC+
DC−
BAT+
BAT−
RB1
RB2
RSNS
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 of f 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
RT1 +5 RTH RTC
3 ǒRTC *RTHǓ
RT2 +5 RTH RTC
ƪǒ2 RTCǓǒ7 RTHǓƫ
(3)
(4)
 
 
SLUS025F − MAY 2001 − REVISED JULY 2002
13
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APPLICATION INFORMATION
battery temperature monitoring (continued)
For PTC Thermistors
RT1 +5 RTH RTC
3 ǒRTH *RTCǓ
RT2 +5 RTH RTC
ƪǒ2 RTHǓǒ7 RTCǓƫ
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 R T2 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.
SNS
BAT
VCC
TS
COMP
CC
VSS
STAT
bq2057
DC+
DC−
BAT+
BAT−
SNS
BAT
VCC
TS
COMP
CC
VSS
STAT
bq2057
DC+
DC−
BAT+
BAT−
RT1
Thermistor
High-Side Current Sensing
Thermistor
RT2
RT1
RT2
RSNS
Low-Side Current Sensing
RSNS
Figure 9. Temperature Sensing Circuits
Temperature Fault
Normal Temperature Range
Temperature Fault
VCC
V(TS2)
V(TS1)
VSS
Figure 10. bq2057 TS Input Thresholds
(5)
(6)
 
 
SLUS025F − MAY 2001 − REVISED JULY 2002
14 www.ti.com
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 STA T pin again. In a high-Z condition, the input port always
matches the signal level on the output port.
SNS
BAT
VCC
TS
COMP
CC
VSS
STAT
bq2057CTS
OUT
IN
Host
Processor
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.
 
 
SLUS025F − MAY 2001 − REVISED JULY 2002
15
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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
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.
θJC +ǒT(J)max *TA(max)Ǔ
PD
θJC +(150–40)
1.4
θJC +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:
bmin +ICMAX
IB
bmin +1
0.035
bmin +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, I C 1.5 A, βmin 28 and that is in a
SOT223 package.
(7)
(8)
(9)
 
 
SLUS025F − MAY 2001 − REVISED JULY 2002
16 www.ti.com
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
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.
θJC +ǒTmax(J)–TA(max)Ǔ
PD
θJC +(150–40)
1
θJC +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
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.
(10)
(11)
(12)
 
 
SLUS025F − MAY 2001 − REVISED JULY 2002
17
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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.
Protection
Controller
Wire Wire Wire
Cell
Wire
Fuse
Discharge Charge
BAT+
BAT−
Terminal
Terminal
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.
 
 
SLUS025F − MAY 2001 − REVISED JULY 2002
18 www.ti.com
APPLICATION INFORMATION
automatic charge-rate compensation (continued)
AutoComp setup requires the following information:
DTotal impedance of battery pack (Z(PACK))
DMaximum 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)
The required compensation is then calculated using the following equations:
V(COMP) +V(Z)
G(COMP)
V(PACK) +VO(REG) )ǒG(COMP) V(COMPǓ
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:
V(COMP)
V(SNS) +RCOMP2
RCOMP1 )RCOMP2
SNS
BAT
VCC
TS
COMP
CC
VSS
STAT
bq2057
DC+
DC−
BAT+
SNS
BAT
VCC
TS
COMP
CC
VSS
STAT
bq2057
DC+
DC−
BAT+
BAT−
High-Side Current Sensing Low-Side Current Sensing
RCOMP2
RSNS
RCOMP1
RCOMP1
RCOMP2
RSNS
Figure 13. AutoComp Circuits
(13)
(14)
(15)
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 
SLUS025F − MAY 2001 − REVISED JULY 2002
19
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APPLICATION INFORMATION
automatic charge-rate compensation (continued)
The following example illustrates these calculations:
Assume Z(PACK) = 100 m, I(REG) = 500 mA, high-side current sensing bq2057C
V(Z) +Z(PACK) I(REG)
V(Z) +0.1 0.5
V(Z) = 50 mV
V(COMP) +V(Z)
G(COMP)
V(COMP) +0.05
2.2
V(COMP) = 22.7 mV
Let RCOMP2 = 10 k
RCOMP1 +
RCOMP2 ǒV(SNS) *V(COMP)Ǔ
V(COMP)
RCOMP1 +10k (105 mV *22.7 mV)
22.7 mV
RCOMP1 +36.25 kW
Use the closest standard value (36.0 k) for RCOMP1
(16)
(17)
(18)
 
 
SLUS025F − M AY 2001 − REVISED JULY 2002
20
www.ti.com
MECHANICAL DATA
Notes:
1.
Dimension Inches 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
D0.1 14 0.122 2.90 3.10
E 0.169 0.176 4.30 4.48
e 0.0256BSC 0.65BSC
H0.246 0.256 6.25 6.50
TS: 8−Pin TSSOP
8−Pin SOIC Narrow (SN)
8−Pin SN (0.150” SOIC )
Dimension
Inches Millimeters
Min. Max. Min. Max.
A 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
D0.185 0.200 4.70 5.08
E 0.150 0.160 3.81 4.06
e 0.045 0.055 1.14 1.40
H0.225 0.245 5.72 6.22
L 0.015 0.035 0.38 0.89
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).
PACKAGE OPTION ADDENDUM
www.ti.com 16-Aug-2012
Addendum-Page 1
PACKAGING INFORMATION
Orderable Device Status (1) Package Type Package
Drawing Pins Package Qty Eco Plan (2) Lead/
Ball Finish MSL Peak Temp (3) Samples
(Requires Login)
BQ2057CDGK ACTIVE VSSOP DGK 8 80 Green (RoHS
& no Sb/Br) CU NIPDAUAGLevel-2-260C-1 YEAR
BQ2057CDGKG4 ACTIVE VSSOP DGK 8 80 Green (RoHS
& no Sb/Br) CU NIPDAUAGLevel-2-260C-1 YEAR
BQ2057CDGKR ACTIVE VSSOP DGK 8 2500 Green (RoHS
& no Sb/Br) CU NIPDAUAGLevel-2-260C-1 YEAR
BQ2057CDGKRG4 ACTIVE VSSOP DGK 8 2500 Green (RoHS
& no Sb/Br) CU NIPDAUAGLevel-2-260C-1 YEAR
BQ2057CSN ACTIVE SOIC D 8 75 Green (RoHS
& no Sb/Br) CU NIPDAU Level-1-260C-UNLIM
BQ2057CSNG4 ACTIVE SOIC D 8 75 Green (RoHS
& no Sb/Br) CU NIPDAU Level-1-260C-UNLIM
BQ2057CSNTR ACTIVE SOIC D 8 2500 Green (RoHS
& no Sb/Br) CU NIPDAU Level-1-260C-UNLIM
BQ2057CSNTRG4 ACTIVE SOIC D 8 2500 Green (RoHS
& no Sb/Br) CU NIPDAU Level-1-260C-UNLIM
BQ2057CTS ACTIVE TSSOP PW 8 150 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
BQ2057CTSG4 ACTIVE TSSOP PW 8 150 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
BQ2057CTSTR ACTIVE TSSOP PW 8 2000 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
BQ2057CTSTRG4 ACTIVE TSSOP PW 8 2000 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
BQ2057DGK ACTIVE VSSOP DGK 8 80 Green (RoHS
& no Sb/Br) CU NIPDAUAGLevel-2-260C-1 YEAR
BQ2057DGKG4 ACTIVE VSSOP DGK 8 80 Green (RoHS
& no Sb/Br) CU NIPDAUAGLevel-2-260C-1 YEAR
BQ2057SN ACTIVE SOIC D 8 75 Green (RoHS
& no Sb/Br) CU NIPDAU Level-1-260C-UNLIM
BQ2057SNG4 ACTIVE SOIC D 8 75 Green (RoHS
& no Sb/Br) CU NIPDAU Level-1-260C-UNLIM
BQ2057TS ACTIVE TSSOP PW 8 150 Green (RoHS
& no Sb/Br) CU NIPDAU Level-1-260C-UNLIM
PACKAGE OPTION ADDENDUM
www.ti.com 16-Aug-2012
Addendum-Page 2
Orderable Device Status (1) Package Type Package
Drawing Pins Package Qty Eco Plan (2) Lead/
Ball Finish MSL Peak Temp (3) Samples
(Requires Login)
BQ2057TSG4 ACTIVE TSSOP PW 8 150 Green (RoHS
& no Sb/Br) CU NIPDAU Level-1-260C-UNLIM
BQ2057TSN ACTIVE SOIC D 8 75 Green (RoHS
& no Sb/Br) CU NIPDAU Level-1-260C-UNLIM
BQ2057TSNG4 ACTIVE SOIC D 8 75 Green (RoHS
& no Sb/Br) CU NIPDAU Level-1-260C-UNLIM
BQ2057TTS ACTIVE TSSOP PW 8 150 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
BQ2057TTSG4 ACTIVE TSSOP PW 8 150 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
BQ2057TTSTR ACTIVE TSSOP PW 8 2000 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
BQ2057TTSTRG4 ACTIVE TSSOP PW 8 2000 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
BQ2057WSN ACTIVE SOIC D 8 75 Green (RoHS
& no Sb/Br) CU NIPDAU Level-1-260C-UNLIM
BQ2057WSNG4 ACTIVE SOIC D 8 75 Green (RoHS
& no Sb/Br) CU NIPDAU Level-1-260C-UNLIM
BQ2057WSNTR ACTIVE SOIC D 8 2500 Green (RoHS
& no Sb/Br) CU NIPDAU Level-1-260C-UNLIM
BQ2057WSNTRG4 ACTIVE SOIC D 8 2500 Green (RoHS
& no Sb/Br) CU NIPDAU Level-1-260C-UNLIM
BQ2057WTS ACTIVE TSSOP PW 8 150 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
BQ2057WTSG4 ACTIVE TSSOP PW 8 150 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
BQ2057WTSTR ACTIVE TSSOP PW 8 2000 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
BQ2057WTSTRG4 ACTIVE TSSOP PW 8 2000 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
(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.
PACKAGE OPTION ADDENDUM
www.ti.com 16-Aug-2012
Addendum-Page 3
(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.
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.
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device Package
Type Package
Drawing Pins SPQ Reel
Diameter
(mm)
Reel
Width
W1 (mm)
A0
(mm) B0
(mm) K0
(mm) P1
(mm) W
(mm) Pin1
Quadrant
BQ2057CDGKR VSSOP DGK 8 2500 330.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1
BQ2057CSNTR SOIC D 8 2500 330.0 12.4 6.4 5.2 2.1 8.0 12.0 Q1
BQ2057CTSTR TSSOP PW 8 2000 330.0 12.4 7.0 3.6 1.6 8.0 12.0 Q1
BQ2057TTSTR TSSOP PW 8 2000 330.0 12.4 7.0 3.6 1.6 8.0 12.0 Q1
BQ2057WSNTR SOIC D 8 2500 330.0 12.4 6.4 5.2 2.1 8.0 12.0 Q1
BQ2057WTSTR TSSOP PW 8 2000 330.0 12.4 7.0 3.6 1.6 8.0 12.0 Q1
PACKAGE MATERIALS INFORMATION
www.ti.com 16-Aug-2012
Pack Materials-Page 1
*All dimensions are nominal
Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm)
BQ2057CDGKR VSSOP DGK 8 2500 367.0 367.0 35.0
BQ2057CSNTR SOIC D 8 2500 367.0 367.0 35.0
BQ2057CTSTR TSSOP PW 8 2000 367.0 367.0 35.0
BQ2057TTSTR TSSOP PW 8