overvoltage protection, reverse charge current protection,
PWM soft-start and robust non-overlap control for an all
N-channel MOSFET PWM power stage.
The device includes AC adapter input current limiting, which
maximizes the 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 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 20V
INFET
DCIN
0.1µF
CLP
CLN
BOOST
TGATE
SW
INTV
DD
BGATE
GND
CSP
25m
0.1µF
5.1k
20µF
POWER TO
SYSTEM
100
95
0.1µF
EFFICIENCY (%)
90
85
80
75
33m
70
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 5 NAME
ACP
X
4012-3 TA02
Efficiency at DCIN = 20V
10000
EFFICIENCY
POWER LOSS (mW)
CHRG
TO/FROM
MCU
ICL
SHDN
ITH
6.04k
0.1µF
PROG
26.7k
4.7nF
POWER LOSS
1000
2µF
6.8µH
3.01k
LTC4012-3
CSN
BAT
FBDIV
V
FB
3.01k
2.5
3
100
301k
32.8k
20µF
+
12.3V
Li-Ion
BATTERY
4012-3 TA01
PART
GND
LTC4012
LTC4012-3
X
40123fb
LTC4012-3
absoluTe MaxiMuM raTings
(Note 1)
pin conFiguraTion
TOP VIEW
INTV
DD
BOOST
BGATE
15 CSP
14 CSN
21
13 PROG
12 ITH
11 BAT
6
SHDN
7
CHRG
8
ICL
9 10
FBDIV
V
FB
TGATE
SW
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
or V
FB
to GND .................................... –0.3V to 7V
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
20 19 18 17 16
CLN 1
CLP 2
INFET 3
DCIN 4
GND 5
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-3#PBF
LTC4012IUF-3#PBF
TAPE AND REEL
LTC4012CUF-3#TRPBF
LTC4012IUF-3#TRPBF
PART MARKING*
40123
40123
PACKAGE DESCRIPTION
20-Lead (4mm
×
4mm) Plastic QFN
20-Lead (4mm
×
4mm) Plastic QFN
TEMPERATURE RANGE
0°C to 85°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/
40123fb
LTC4012-3
elecTrical characTerisTics
SYMBOL
V
TOL
I
VFB
R
ON
I
LEAK-FBDIV
V
BOV
I
TOL
PARAMETER
V
BAT
Accuracy (See Test Circuits)
V
FB
Input Bias Current
FBDIV On Resistance
FBDIV Output Leakage Current
V
FB
Overvoltage Threshold
Charge Current Accuracy with R
IN
= 3.01k,
6V < BAT < 18V
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
IL
V
IH
R
IN
I
CLPS
I
LEAK-BAT
I
LEAK-CSN
I
LEAK-CSP
I
LEAK-SW
SHDN
Input Voltage Low
SHDN
Input Voltage High
SHDN
Pull-Down Resistance
CLP Shutdown Current
BAT Leakage Current
CSN Leakage Current
CSP Leakage Current
SW Leakage Current
CLP = 12V, DCIN = 0V
SHDN
= 0V
SHDN
= 0V or DCIN = 0V,
0V ≤ CSP = CSN = BAT ≤ 18V
SHDN
= 0V or DCIN = 0V,
0V ≤ CSP = CSN = BAT ≤ 20V
SHDN
= 0V or DCIN = 0V,
0V ≤ CSP = CSN = BAT ≤ 20V
SHDN
= 0V or DCIN = 0V,
0V ≤ SW ≤ 20V
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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