age battery charger controller. It uses a synchronous
quasi-constant frequency PWM control architecture
that will not generate audible noise with ceramic bulk
capacitors. Charge current is set by external resis-
tors and can be monitored as an output voltage.
With no built-in termination, the LTC4012 family charges
a wide range of batteries under external control.
The LTC4012 features fully adjustable output voltage, while
the LTC4012-1 and LTC4012-2 can be pin-programmed for
Lithium-Ion/Polymer battery packs of 1-, 2-, 3- or 4-series
cells. The LTC4012-1 provides output voltage of 4.1V/cell
and the LTC4012-2 is a 4.2V/cell version.
The device includes AC adapter input current limiting, which
maximizes charge rate for a fixed input power level. An
external sense resistor programs the input current limit,
and the
ICL
status pin indicates reduced charge current as
a result of AC adapter current limiting. Ideal diode control
at the adaptor input improves charger efficiency.
The
CHRG
status pin is active during all charging modes,
including special indication for low charge current.
General Purpose Battery Charger Controller
n
Efficient 550kHz Synchronous Buck PWM Topology
n
±0.5% Output Float Voltage Accuracy
n
Programmable Charge Current: 4% Accuracy
n
Programmable AC Adapter Current Limit:
3% Accuracy
n
No Audible Noise with Ceramic Capacitors
n
INFET Low Loss Ideal Diode PowerPath™ Control
n
Wide Input Voltage Range: 6V to 28V
n
Wide Output Voltage Range: 2V to 28V
n
Indicator Outputs for AC Adapter Present, Charging,
C/10 Current Detection and Input Current Limiting
n
Analog Charge Current Monitor
n
Micropower Shutdown
n
20-Pin 4mm
×
4mm
×
0.75mm QFN Package
applications
n
n
n
Notebook Computers
Portable Instruments
Battery Backup Systems
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
PowerPath and ThinSOT are trademarks of Linear Technology Corporation. All other trademarks
are the property of their respective owners. Protected by U.S. Patents including 5723970.
typical application
FROM
ADAPTER
13V TO 28V
INFET
DCIN
0.1µF
ACP
TO/FROM
MCU
CHRG
ICL
SHDN
ITH
6.04k
0.1µF
PROG
26.7k
4.7nF
CLP
CLN
BOOST
TGATE
SW
INTV
DD
BGATE
GND
CSP
LTC4012
CSN
BAT
FBDIV
V
FB
32.8k
25m
0.1µF
5.1k
20µF
POWER TO
SYSTEM
Efficiency at DCIN = 20V
100
95
EFFICIENCY (%)
EFFICIENCY
POWER LOSS (mW)
10000
0.1µF
90
85
80
75
70
POWER LOSS
1000
2µF
6.8µH
3.01k
33m
V
OUT
= 12.3V
R
SENSE
= 33m
R
IN
= 3.01k
R
PROG
= 26.7k
0
0.5
1
1.5
2
CHARGE CURRENT (A)
PIN NAME
2.5
3
100
3.01k
301k
20µF
+
12.3V
Li-Ion
BATTERY
4012 TA01
PART INFET DCDIV
LTC4009
X
LTC4012
X
4012 TA02
4012fa
LTC4012/
LTC4012-1/LTC4012-2
absolute MaxiMuM ratings
(Note 1)
DCIN ............................................................–14V to 30V
DCIN to CLP ................................................ –32V to 20V
CLP, CLN or SW to GND............................. –0.3V to 30V
CLP to CLN ............................................................±0.3V
CSP, CSN or BAT to GND ........................... –0.3V to 28V
CSP to CSN ............................................................±0.3V
BOOST to GND ........................................... –0.3V to 36V
BOOST to SW............................................... –0.3V to 7V
SHDN,
FVS0, FVS1 or V
FB
to GND ............... –0.3V to 7V
ACP, CHRG
or
ICL
to GND .......................... –0.3V to 30V
Operating Temperature Range
(Note 2) ............................................. –40°C to 125°C
Junction Temperature (Note 3) ............................. 125°C
Storage Temperature Range .................. –65°C to 150°C
pin conFiguration
LTC4012
TOP VIEW
INTV
DD
BOOST
BGATE
TGATE
SW
LTC4012-1
LTC4012-2
BOOST
TOP VIEW
INTV
DD
BGATE
15 CSP
21
GND
14 CSN
13 PROG
12 ITH
11 BAT
6
SHDN
7
CHRG
8
ICL
9 10
FVS0
FVS1
TGATE
SW
20 19 18 17 16
CLN 1
CLP 2
INFET 3
DCIN 4
ACP
5
6
SHDN
7
CHRG
8
ICL
9 10
V
FB
FBDIV
21
GND
15 CSP
14 CSN
13 PROG
12 ITH
11 BAT
CLN 1
CLP 2
INFET 3
DCIN 4
ACP
5
20 19 18 17 16
UF PACKAGE
20-LEAD (4mm 4mm) PLASTIC QFN
T
JMAX
= 125°C,
JA
= 37°C/W
EXPOSED PAD (PIN 21) IS GND, MUST BE SOLDERED TO PCB
UF PACKAGE
20-LEAD (4mm 4mm) PLASTIC QFN
T
JMAX
= 125°C,
JA
= 37°C/W
EXPOSED PAD (PIN 21) IS GND, MUST BE SOLDERED TO PCB
orDer inForMation
LEAD FREE FINISH
LTC4012CUF#PBF
LTC4012CUF-1#PBF
LTC4012CUF-2#PBF
LTC4012IUF#PBF
LTC4012IUF-1#PBF
LTC4012IUF-2#PBF
TAPE AND REEL
LTC4012CUF#TRPBF
LTC4012CUF-1#TRPBF
LTC4012CUF-2#TRPBF
LTC4012IUF#TRPBF
LTC4012IUF-1#TRPBF
LTC4012IUF-2#TRPBF
PART MARKING*
4012
40121
40122
4012
40121
40122
PACKAGE DESCRIPTION
20-Lead (4mm
×
4mm) Plastic QFN
20-Lead (4mm
×
4mm) Plastic QFN
20-Lead (4mm
×
4mm) Plastic QFN
20-Lead (4mm
×
4mm) Plastic QFN
20-Lead (4mm
×
4mm) Plastic QFN
20-Lead (4mm
×
4mm) Plastic QFN
TEMPERATURE RANGE
0°C to 85°C
0°C to 85°C
0°C to 85°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
4012fa
LTC4012/
LTC4012-1/LTC4012-2
electrical characteristics
SYMBOL
V
TOL
PARAMETER
V
BAT
Accuracy (See Test Circuits)
Charge Voltage Regulation
LTC4012
C-Grade
I-Grade
LTC4012-1/LTC4012-2
C-Grade
FVS1 = 0V, FVS0 = 0V, I-Grade
FVS1 = 0V, FVS1 = 5V, I-Grade
FVS1 = 5V, FVS0 = 0V, I-Grade
FVS1 = 5V, FVS1 = 5V, I-Grade
I
VFB
R
ON
I
LEAK-FBDIV
V
BOV
V
FB
Input Bias Current
FBDIV On Resistance
FBDIV Output Leakage Current
V
FB
Overvoltage Threshold
BAT Overvoltage Threshold
Charge Current Regulation
I
TOL
Charge Current Accuracy with R
IN
= 3.01k,
6V < BAT < 18V (LTC4012)
6V < BAT < 15V (LTC4012-1, LTC4012-2)
Current Sense Amplifier Gain (PROG ∆I) with
R
IN
= 3.01k, 6V < BAT < 18V (LTC4012)
6V < BAT < 15V (LTC4012-1, LTC4012-2)
Maximum Peak Current Sense Threshold Voltage
per Cycle (R
IN
= 3.01k)
C/10 Indicator Threshold Voltage
Reverse Current Threshold Voltage
Current Limit Threshold
R
PROG
= 26.7k
C-Grade
I-Grade
V
SENSE
= 0mV, PROG = 1.2V
A
I
V
CS-MAX
V
C10
V
REV
V
CL
I
CLN
V
ICL
CLP Supply
OVR
V
UVLO
V
UV(HYST)
I
CLPO
Shutdown
V
ACP
V
ACP(HYST)
V
IL
V
IH
AC Present Threshold Voltage
DCIN – BAT, DCIN Rising
C-Grade
I-Grade
l
l
l
l
l
l
l
l
l
l
l
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
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