Datasheet

UNISONIC TECHNOLOGIES CO., LTD
UB2012
LINEAR INTEGRATED CIRCUIT
ADVANCED LINEAR CHARGE
MANAGEMENT IC FOR SINGLE
AND TWO-CELL LITHIUM-ION AND
LITHIUM-POLYMER

DESCRIPTION
UTC UB2012 is designed for portable electronics with lower cost. Its
advantages of high-accuracy voltage/current regulation, charging status
indication, temperature monitoring, and automatic charge-rate compensation.
In applications, the battery temperature is continuously under monitor
by using an external thermistor, if the temperature is over user-defined
threshold; UTC UB2012 inhibits charge for safety concern.
Generally, the UTC UB2012 charges the battery in conditioning, constant voltage and constant current phases.
If the battery voltage is lower than the low-voltage threshold (VMIN), a low current is used for conditioning the battery.
The conditioning charge rate is around 10% of the regulation current and the heat dissipation in the external pass
element during the initial stage of the charge is minimized by the conditioning current. After the conditioning phase,
the UTC UB2012 applies a constant current that be set by an external sense-resistor to the battery. The
sense-resistor can be on the battery without additional components. The constant current phase continues until the
battery reaches the charge-regulation voltage, then the constant voltage phase is beginning.
UTC UB2012 offers 4.1V, 4.2V, 8.4V and 8.4V fixed-voltage for single and dual cells. Charge stops when the
current tapers to the charge termination threshold (ITERM) and will recharge if the battery voltage falls below the VRCH.
The automatic charge-rate compensation feature reduces the charging time of batteries. For the internal
impedance of battery pack during charge, this advanced technique offers safe and dynamic compensation.

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FEATURES
Ideal for Single 4.1V,4.2V and Dual-Cell 8.2V,8.4V Li-Ion or Li-Pol Packs
0.3V Dropout Voltage for Minimizing Heat Dissipation
Better than ±1% Accuracy of Voltage Regulation With Preset Voltages
Dynamic Compensation of Battery Pack’s Internal Impedance to short Charging Time
Optional Cell-Temperature Monitoring
Integrated Voltage and Current Regulation With Programmable Charge-Current
Integrated Cell Conditioning for Reviving Deeply Discharged Cells and Minimizing Heat Dissipation During Initial
Charge Stage
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
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ORDERING INFORMATION
Note:



LINEAR INTEGRATED CIRCUIT
Ordering Number
UB2012xG-S08-R
x: Output Voltage, refer to Marking Information.
Package
SOP-8
Packing
Tape Reel
MARKING INFORMATION
PACKAGE
VOLTAGE CODE
SOP-8
A: 4.1V
B: 4.2V
C: 8.2V
D: 8.4V
MARKING
UTC
UB2012xG
Date Code
Voltage Code
Lot Code
PIN CONFIGURATION
SNS
1
8
BAT
2
7
CC
VCC
3
6
VSS
TS
4
5
STAT
COMP
PIN DESCRIPTION
PIN NO.
1
2
3
4
5
6
7
8
PIN NAME
SNS
BAT
VCC
TS
STAT
VSS
CC
COMP
I/O
I
I
I
I
O
O
I
PIN DESCRIPTION
Current sense input
Voltage sense input
Supply voltage
Temperature sense input
Charge status output
Ground
Charge control output
Charge-Rate compensation input (Auto Comp)
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LINEAR INTEGRATED CIRCUIT
BLOCK DIAGRAM

VCC
Reference
VO(REG)
V(TS)
TS
VCC
V(TS)
VO(REG)
V(BAT)
TS2
Sleep Mode
V(BAT)
COMP
V(TS)
G(COMP)
Voltage Regulation
TS1
V(BAT)
CC
Battery Recharge
Control
Logic
V(BAT)
Battery Conditioning
SNS
V(SNS)
V(SNS)
VCC-V(SNS)
VSS-V(SNS)
Driver
VCC
High/Low SNS Set
Driver
VCC/2
V(SNS)
STAT
Current Regulation
Driver
Voltage Termination
VSS
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LINEAR INTEGRATED CIRCUIT
ABSOLUTE MAXIMUM RATING (unless otherwise specified.)
PARAMETER
SYMBOL
RATINGS
UNIT
VCC
-0.3 ~ +8.0
V
VCC
-0.3 ~ +15
V
UB2012A
UB2012B
UB2012C
UB2012D
Supply Voltage
(VCC with respect to GND)
Input Voltage, SNS, BAT,TS, COMP
VIN
-0.3 ~ VCC +0.3
V
(all with respect to GND)
Sink Current (Note 2)
STAT pin
ISINK
20
mA
Source Current (Note 2)
STAT pin
ISOURCE
10
mA
Output Current (Note 2)
CC pin
IOUT
40
mA
Power Dissipation (TA=25°C)
PD
300
mW
Operating Temperature
TOPR
-20 ~ +85
°C
Storage Temperature
TSTG
-40 ~ +125
°C
Notes: 1. Absolute maximum ratings are those values beyond which the device could be permanently damaged.
Absolute maximum ratings are stress ratings only and functional device operation is not implied.
2. Not to exceed PD.

RECOMMENDED OPERATING CONDITIONS
PARAMETER
SYMBOL
MIN
VCC
UB2012A
UB2012B
Supply Voltage
UB2012C
UB2012D
Operating Free-Air Temperature Range

TYP
MAX
UNITS
4.5
7.0
V
VCC
8.6
12
V
TA
-20
85
°C
ELECTRICAL CHARACTERISTICS
PARAMETER
VCC Current
SYMBOL
I(VCC)
VCC Sleep Current
I(VCCS)
BAT Pin
IIB(BAT)
SNS Pin
IIB(SNS)
Input Bias Current
TS Pin
IIB(TS)
COMP Pin IIB(COMP)
BATTERY VOLTAGE REGULATION
Output Voltage
CONDITIONS
VCC>VCC(MIN), Excluding
external loads
V(BAT)≥V(MIN)
V(BAT)-VCC≥0.8V
MIN
UB2012A
UB2012B
UB2012C
UB2012D
UB2012A
UB2012B
UB2012C
UB2012D
TYP
MAX
UNITS
2
5
mA
3
7
mA
3
6
μA
15
μA
3
5
5
5
μA
μA
μA
μA
V(BAT)=V(REG)
V(SNS)=5V
V(TS)=5V
V(COMP)=5V
VO(REG) See Notes
UB2012A
UB2012B
UB2012C
UB2012D
4.050
4.150
8.100
8.300
4.10
4.20
8.20
8.40
4.150
4.250
8.300
8.500
V
V
V
V
80
100
120
mV
90
115
140
mV
-24
-14
-4
mV
CURRENT REGULATION
Current Regulation Threshold
V(SNS)
current sensing
configuration
UB2012A
UB2012B
UB2012C
UB2012D
CHARGE TERMINATION DETECTION
Charge Termination Current
V(TERM) Voltage at pin SNS, 0°C≤TA≤50°C
Detect Threshold
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LINEAR INTEGRATED CIRCUIT
ELECTRICAL CHARACTERISTICS
TEMPERATURE COMPARATOR
Lower
V(TS1)
Temperature Threshold
Upper
V(TS2)
PRECHARGE COMPARATOR
Precharge Threshold
TS Pin Voltage
V(MIN)
UB2012A
UB2012B
UB2012C
UB2012D
29.1
58.2
30
60
30.9
61.8
%VCC
%VCC
2.94
3.04
5.88
6.08
3.0
3.1
6.0
6.2
3.06
3.16
6.12
6.32
V
V
V
V
PRECHARGE CURRENT REGULATION
Voltage at pin SNS, 0°C≤TA≤50°C
V(PRECHG) Voltage at pin SNS,
0°C≤TA≤50°C, VCC = 5 V
VRCH COMPARATOR (BATTERY RECHARGE THRESHOLD)
UB2012A
UB2012B
Recharge Threshold
V(RCH)
UB2012C
UB2012D
CHARGE-RATE COMPENSATION (Automatic Charge-Rate Compensation)
Automatic Charge-Rate
G(COMP) V(BAT)+0.3V≤VCC≤VCC(MAX),
Compensation Gain
STAT PIN
Output (Low) Voltage
VOL(STAT) IOL=10mA
Output (High) Voltage
VOH(STAT) IOH=5mA
CC PIN
Output Low Voltage
VOL(CC) IO(CC)=5mA (sink)
Sink Current
IO(CC) Not to exceed power rating (PD)
Note:
V(BAT) +0.3 V≤VCC≤VCC(MAX)
Precharge Current Regulation
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13
3
13
mV
22
mV
VO(REG) VO(REG- VO(REG)
-70mV -100mV -130mV
VO(REG) VO(REG) VO(REG)
-140mV -200mV -260mV
1.7
2.2
V
2.7
V/V
0.7
V
V
1.6
40
V
mA
VCC-0.5
5
V
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LINEAR INTEGRATED CIRCUIT
TYPICAL APPLICATION CIRCUIT
DC+
PACK+
RSNS
0.2Ω
Q1
2SB1151
D1
C1
10μF
VCC
R1
1kΩ
PACKNTC
VCC
CC
SNS
VCC
C2
10μF
VSS
COMP
UB2012
RT1
BAT
TS
STAT
GND
D2
RT2
TEMP
Battery
Pack
R2
2kΩ
Fig. 1 0.5A Low Dropout Li-Lon/Li-Pol Charger
FUNCTIONAL DESCRIPTION
The UTC UB2012 is designed for the applications of single or two-cell Li-Ion or Li-Pol batteries. Fig. 1 is the
schematic of using this advanced linear charge controller with a PNP pass transistor. Fig. 2 is the operation flowchart
of UTC UB2012. Fig. 3 shows the typical charge profile. Fig. 4 is the application schematic of a charger using
P-channel MOSFET.
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LINEAR INTEGRATED CIRCUIT
APPLICATION INFORMATION
POR
Sleep Mode
VCC>V(BAT)
Checked at
All Times
No
Indicate SLEEP
MODE (STAT=Hi-Z)
Yes
Suspend Charge
TS Pin in
TS1 to TS2
Range
No
Indicate CHARGE
SUSPEND
(STAT=Hi-Z)
Yes
Regulate I(PRECHG)
Yes
V(BAT)<V(MIN)
Indicate Charge
In-Progress
(STAT=High)
Suspend Charge
No
TS Pin in
TS1 to TS2
Range
Regulate Current
or Voltage
No
Indicate Charge
In-Progress
(STAT=High)
Yes
No
Suspend Charge
TS Pin in
TS1 to TS2
Range
No
Yes
Yes
Indicate CHARGE
SUSPEND
(STAT=Hi-Z)
Indicate CHARGE
SUSPEND
(STAT=Hi-Z)
TS Pin in
TS1 to TS2
Range
TS Pin in
TS1 to TS2
Range
V(BAT)<V(MIN)
No
Yes
No
Yes
V(BAT)<V(MIN)
No
Terminate Charge
Yes
I(TERM)
Delected
Yes
Indicate CHARGE
DONE
(STAT=Low)
V(BAT)<V(RCH)
No
Yes
Fig. 2 Operation Flowchart
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LINEAR INTEGRATED CIRCUIT
APPLICATION INFORMATION(Cont.)
Preconditionin
g Phase
Current Regulation
Phase
Voltage Regulation and
Charge Termination Phase
Regulation Voltage
Regulation Current
Minimum Charge
Voltage
Preconditioning
and Taper Detect
Fig. 3 Typical Charge Profile
QUALIFICATION AND PRECHARGE
When the battery is present and power is applied, the UTC UB2012 starts a charge-cycle. Charge qualification
is affected by battery temperature and voltage. If the battery temperature is out of the VTS1 to VTS2 range; the UTC
UB2012 will suspend charge. In addition, if the battery voltage is below the precharge threshold V(MIN), the UTC
UB2012 uses precharge to condition the battery. The conditioning charge rate I(PRECHG) is set at approximately 10%
of the regulation current, and the conditioning current minimizes heat dissipation in the external pass-element during
the beginning of charge, refer to Fig. 3.
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LINEAR INTEGRATED CIRCUIT
APPLICATION INFORMATION(Cont.)
PACK+
DC+
Q1
UT4101
RSNS
0.2Ω
D1
C2
10μF
VCC
R2
1kΩ
CC
UTC
UB2012
PACKNTC
VCC
COMP
SNS
BAT
VCC
TS
VSS
STAT
RT1
TEMP
RT2
Battery
Pack
R4
511Ω
GND
C1
10μF
R5
1kΩ
R3
1kΩ
CMD6722SRU
Fig. 4 0.5-A Charger Using P-Channel MOSFET
CURRENT REGULATION PHASE
When the battery-pack voltage is less than the regulation voltage, VO(REG), the current is regulated by the UTC
UB2012. This advanced linear charge management IC monitors charge current at the SNS input by the voltage drop
across a sense-resistor, RSNS, in series with the battery pack. In current sensing configuration (Fig. 5), RSNS is
between the VCC and SNS pins. Charge-current feedback, applied through pin SNS, maintains a voltage of VSNS
across the current sense resistor. The following formula calculates the value of the sense resistor:
V(SNS)
R SNS 
(1)
IO(REG)
Where IO(REG) is the desired charging current.
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LINEAR INTEGRATED CIRCUIT
APPLICATION INFORMATION(Cont.)
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 UTC UB2012 monitors the battery-pack voltage between the BAT and VSS pins. According to the
voltage regulation, there are four versions of UTC UB2012, namely, 4.1V, 4.2V, 8.2V and 8.4V.
Other regulation voltages can be achieved by adding a voltage divider between the positive and negative
terminals of the battery pack and using UTC UB2012C or UTC UB2012D. The voltage divider presents scaled
battery-pack voltage to BAT input. (See Fig. 7, 8) The resistor values RB1 and RB2 for the voltage divider are
calculated by the following equation:
RB1
V(CELL)
= (N ×
) -1
RB2
VO(REG)
(2)
Where: N = Number of cells in series, V(CELL) = Desired regulation voltage per cell
CHARGE TERMINATION AND RECHARGE
The UTC UB2012 monitors the charging current during the voltage-regulation phase. The UTC UB2012
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.
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LINEAR INTEGRATED CIRCUIT
APPLICATION INFORMATION(Cont.)
BATTERY TEMPERATURE MONITORING
The UTC UB2012 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 Fig. 9) The UTC UB2012 compares this voltage against its internal V(TS1) and V(TS2)
thresholds to determine if charging is allowed. (See Fig. 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 × R TH × R TC
3 × (RTC - RTH )
RT 2 =
(3)
5 × RTH × RTC
[(2 × RTC ) - (7 × RTH )]
(4)
For PTC Thermistors:
RT1 =
5 × R TH × R TC
3 × (RTH - R TC )
RT 2 =
(5)
5 × RTH × RTC
[(2 × RTH ) - (7 × R TC )]
(6)
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.
RSNS
DC+
BAT+
UTC
UB2012
SNS COMP
RT1
BAT
VCC
DC-
TS
CC
VSS
STAT
RT2
BATThermistor
Fig. 7 Temperature Sensing Circuits
Fig. 8 UTC UB2012 TS Input Thresholds
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LINEAR INTEGRATED CIRCUIT
APPLICATION INFORMATION(Cont.)
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 UTC UB2012 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 (Fig. 4) or for interface to a host or
system processor (Fig. 11). When interfacing the UTC UB2012 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
UTC
UB2012
SNS
COMP
BAT
CC
VCC
VSS
TS
STAT
OUT
IN
Figure 9 Interfacing the UTC UB2012 to a Host Processor
LOW-POWER SLEEP MODE
The UTC UB2012 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.
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LINEAR INTEGRATED CIRCUIT
APPLICATION INFORMATION(Cont.)
SELECTING AN EXTERNAL PASS-TRANSISTOR
The UTC UB2012 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 = 4.5V, I(REG) = 1A, 4.2-V single-cell Li-Ion (UTC
UB2012C). VI is the input voltage to the charger and I (REG) is the desired charge current (see Fig. 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 3V 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-V(CS)-V(BAT))×I(REG)
(7)
PD = (4.5-0.1-3)×1A
PD = 1.4W
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.
(TMAX(J) - TA(MAX) )
θJA =
(8)
PD
(150 - 40)
θJA =
1 .4
θJA = 78°C/W
Now choose a device package with a theta at least 10% below this value to account for additional thetas other
than the device. A SOT-223 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:
βMIN =ICMAX / IB
βMIN =1 / 0.035
βMIN =28
(9)
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).
Now choose a PNP transistor that is rated for V(CE) ≥15 V, θJA ≤ 78°C /W, IC ≥ 1.5 A, βMIN ≥ 28 and that is in a
SOT-223 package.
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LINEAR INTEGRATED CIRCUIT
APPLICATION INFORMATION(Cont.)
SELECTING AN EXTERNAL PASS-TRANSISTOR (Cont.)
P-CHANNEL MOSFET:
Selection steps for a P-channel MOSFET: Example: VI = 5.5 V, I(REG) = 500mA, 4.2-V single-cell Li-Ion (UTC
UB2012C). 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)
(10)
PD = (5.5-0.4-0.1-3)×0.5A
PD = 1W
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.
(TMAX(J) - TA(MAX) )
θJA =
(11)
PD
(150 - 40)
θJA =
1
θJA = 110°C/W
Now choose a device package with a theta at least 10% below this value to account for additional thetas other
than the device. A SOP-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 12V 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 UTC UB2012.
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≤-15V, θJA ≤110°C /W, ID ≥1A, V(GSTH)≥-3.5V
and in a SOP package.
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APPLICATION INFORMATION(Cont.)
SELECTING INPUT CAPACITOR
In most applications, a high-frequency decoupling capacitor is required. A 0.1μF ceramic, placed in proximity to
VCC and VSS pins, works well. The UTC UB2012 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, otherwise more capacitance must be added to the input of the
charger.
SELECTING OUTPUT CAPACITOR
For loop stability, the UTC UB2012 does not require any output capacitor. However, when a battery is not
present, the user can add output capacitance in order to control the output voltage. 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
In order to compensate safely for internal impedance of the battery pack, the UTC UB2012 uses the automatic
charge-rate compensation technique to reduce charging time. The automatic charge-rate compensation feature is
disabled by connecting the COMP pin to VCC in current-sensing configuration.
Fig. 12 outlines the main components of a single-cell Li-Ion battery pack. The Li-Ion battery pack consists of a
cell, protection circuit, fuse, current sense-resistors, connector, and some wiring. There are some resistances in
each of these components. Total impedance of the battery pack is equal to 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
BATTerminal
Wire
Wire
Discharge
Wire
Charge
Fig. 10 Typical Components of a Single-Cell Li-lon Pack
Compensation is achieved through input pin COMP (Fig. 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.
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
LINEAR INTEGRATED CIRCUIT
APPLICATION INFORMATION(Cont.)
Automatic charge-rate compensation setup requires the following information:
* Total impedance of battery pack (Z(PACK))
* 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:
(13)
V( Z ) = Z(PACK ) × I(REG )
The required compensation is then calculated using the following equations:
V( COMP ) =
V( Z )
G( COMP )
(14)
V(PACK ) = VO(REG ) + (G( COMP ) × V( COMP ) )
Where V(COMP) is the voltage on COMP pin. This voltage is referenced to VCC in current sensing configuration.
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 )
RCOMP 2
=
V( SNS )
RCOMP1 + RCOMP 2
(15)
BAT+
DC+
RCOMP2
RCOMP1
RSNS
DC-
UTC
UB2012
SNS COMP
BAT
CC
VCC
VSS
TS
STAT
Fig. 11 Automatic Charge-Rate Compensation Circuits
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LINEAR INTEGRATED CIRCUIT
APPLICATION INFORMATION(Cont.)
The following example illustrates these calculations:
Assume Z(PACK) = 100 mΩ , I(REG) = 500 mA, current sensing UTC UB2012B
V( Z ) = Z(PACK ) × I(REG )
(16)
V(Z)=0.1×0.5
V(Z)=50mV
V( COMP ) =
V( Z )
G( COMP )
(17)
V(COMP)=0.05/2.2
V(COMP)=22.7mV
Let RCOMP2 = 10 kΩ
RCOMP1 =
RCOMP 2 × ( V( SNS ) - V( COMP ) )
V( COMP )
RCOMP1 = 10k ×
(18)
(105mV - 22.7mV )
22.7mV
R COMP1  36.25kΩ
Use the closest standard value (36.0 kΩ) for RCOMP1
UTC assumes no responsibility for equipment failures that result from using products at values that
exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or
other parameters) listed in products specifications of any and all UTC products described or contained
herein. UTC products are not designed for use in life support appliances, devices or systems where
malfunction of these products can be reasonably expected to result in personal injury. Reproduction in
whole or in part is prohibited without the prior written consent of the copyright owner. The information
presented in this document does not form part of any quotation or contract, is believed to be accurate
and reliable and may be changed without notice.
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www.unisonic.com.tw
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