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PDF LTC4007-1 Data sheet ( Hoja de datos )
| Número de pieza | LTC4007-1 | |
| Descripción | Li-Ion Battery Charger | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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LTC4007-1www.DataSheet4U.com
4A, High Efficiency,
Li-Ion Battery Charger
FEATURES
DESCRIPTIO
■ Charger Controller for 3- or 4-Cell
Lithium-Ion Batteries
■ High Conversion Efficiency: Up to 96%
■ Output Currents Exceeding 4A
■ ±0.8% Charging Voltage Accuracy
■ Built-In Charge Termination for Li-Ion Batteries
■ AC Adapter Current Limiting Maximizes Charge Rate*
■ Thermistor Input for Temperature Qualified Charging
■ Wide Input Voltage Range: 6V to 28V
■ 0.5V Dropout Voltage; Maximum Duty Cycle: 98%
■ Programmable Charge Current: ±4% Accuracy
■ Indicator Outputs for Charging, C/10 Current
Detection, AC Adapter Present, Low Battery, Input
Current Limiting and Faults
■ Charging Current Monitor Output
■ Available in a 24-Pin 4mm × 5mm QFN Package
U
APPLICATIO S
■ Notebook Computers
■ Portable Instruments
■ Battery-Backup Systems
■ Li-Ion Chargers
The LTC®4007-1 is a constant-current/constant-voltage
charger controller for 3- or 4-cell lithium-ion batteries.
The PWM controller uses a synchronous, quasi-constant
frequency, constant off-time architecture that will not
generate audible noise even when using ceramic capaci-
tors. Charging current is programmable to ±4% accuracy
using a programming resistor. Charging current can also
be monitored as a voltage across the programming
resistor.
The output float voltage is pin programmed for cell count
(3 cells or 4 cells) and chemistry (4.2V/4.1V). A timer,
programmed by an external resistor, sets the total charge
time.
The LTC4007-1 includes a thermistor input, which sus-
pends charging if an unsafe temperature condition is de-
tected. If the cell voltage is less than 3.25V, a low-battery
indicator asserts and can be used to program a trickle charge
current to safely charge depleted batteries. The FAULT pin
is also asserted and charging terminates if the low-battery
condition persists for more than 1/4 of the total charge time.
, LTC and LT are registered trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
*Protected by U.S. Patents including 5723970.
TYPICAL APPLICATIO
DCIN
0V TO 28V
VLOGIC
100k 100k 100k
3C4C
CHEM
DCIN
INFET
LOBAT
LOBAT
CLP
ICL ICL LTC4007-1 CLN
ACP ACP TGATE
SHDN
SHDN
BGATE
FAULT
FAULT
PGND
CHG CHG CSP
FLAG
32.4k
FLAG
NTC
BAT
PROG
THERMISTOR
10k
NTC
0.47µF
RT
ITH
GND
309k
TIMING RESISTOR
(~2 HOURS)
12.6V, 4A Li-Ion Battery Charger
INPUT SWITCH
0.1µF
4.99k
15nF 0.025Ω
20µF
Q1 10µH
SYSTEM
LOAD
0.025Ω
Q2
3.01k
3.01k
6.04k
0.0047µF
0.12µF
26.7k
Q1: Si4431BDY
Q2: FDC645N
20µF
CHARGING
CURRENT
MONITOR
40071 TA01
PART
LOW BATTERY
AUTO THRESHOLD (Per Cell)
RESTART
(4.2V/4.1V)
LTC4007-1 NO
3.25V/3.173V
LTC4007
YES
2.5V/2.44V
Li-Ion
BATTERY
40071f
1
1 page  
TYPICAL PERFOR A CE CHARACTERISTICS
LTC4007-1www.DataSheet4U.com
INFET Response Time to
Reverse Current
Vgs = 0
Vgs OF PFET (2V/DIV)
Vs OF PFET (5V/DIV)
Vs = 0V
Id (REVERSE) OF
PFET (5A/DIV)
Id = 0A
1.25µs/DIV
TEST PERFORMED ON DEMOBOARD
VIN = 15VDC
CHARGER = ON
VCHARGE = 12.6V
PFET = 1/2 Si4925DY
ICHARGE = <10mA
40071 G01
PWM Frequency vs Duty Cycle
350
300
250
200
Line Regulation
0.10
0.05
0
–0.05
–0.10
C3C4 = OPEN
–0.15
–0.20
–0.25
C3C4 = GND
–0.30
–0.35
–0.40
–0.45
13 15 17 19 21 23 25 27 29 31
VDCIN (V)
40071 G02
Disconnect/Reconnect Battery
(Load Dump)
VFLOAT
1V/DIV
3A STEP
1A STEP
1A STEP
VOUT vs IOUT
0
–0.5
–1.0
–1.5
–2.0
–2.5
–3.0
–3.5
–4.0
–4.5
–5.0
0
3C4C = GND
3C4C = OPEN
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
OUTPUT CURRENT (A)
40071 G03
1A Load Step (Battery Present)
CHARGER CURRENT (1A/DIV)
150
PROGRAMMED CURRENT = 10%
100
50 DCIN = 15V
DCIN = 20V
0 DCIN = 24V
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
DUTY CYCLE (VOUT/VIN)
40071 G04
LOAD
STATE
3A STEP
DISCONNECT
RECONNECT
LOAD CURRENT = 1A, 2A, 3A
DCIN = 20V
VFLOAT = 12.6V (3C4C = GND, CHEM = OPEN)
40071 G05
OUTPUT VOLTAGE (500mV/DIV)
DCIN = 20V
VFLOAT = 12.6V
1A Load Step
(Battery Not Present)
Battery Leakage Current vs
Battery Voltage
40
VDCIN = 0V
35
30
CHARGER CURRENT (500mA/DIV)
25
20
OUTPUT VOLTAGE (5V/DIV)
15
10
5
DCIN = 20V
VFLOAT = 12.6V
40071 G07
0
0 5 10 15 20 25 30
BATTERY VOLTAGE (V)
40071 G08
40071 G06
40071f
5
5 Page 
U
OPERATIO
LTC4007-1: State Diagram
MASTER
SHUTDOWN
2
1
ANY
SHUTDOWN
4
5, 6, 7
CONDITION
11
3, 8,
9, 10
3, 17, 18,
19, 20, 21
CHARGE
LTC4007-1www.DataSheet4U.com
12, 13, 14, 15, 16
40071 TBL01
gate of the input FET is driven to a voltage sufficient to keep
a low forward voltage drop from drain to source. If the
voltage between DCIN and CLN drops to less than 25mV,
the input FET is turned off slowly. If the voltage between
DCIN and CLN is ever less than – 25mV, then the input FET
is turned off in less than 10µs to prevent significant
reverse current from flowing in the input FET. In this
condition, the ACP pin is driven low and the charger is
disabled.
Battery Charger Controller
The LTC4007-1 charger controller uses a constant off-
time, current mode step-down architecture. During nor-
mal operation, the top MOSFET is turned on each cycle
when the oscillator sets the SR latch and turned off when
the main current comparator ICMP resets the SR latch.
While the top MOSFET is off, the bottom MOSFET is turned
on until either the inductor current trips the current com-
parator IREV or the beginning of the next cycle. The
oscillator uses the equation:
tOFF
=
VDCIN –
VDCIN •
VBAT
fOSC
to set the bottom MOSFET on time. The result is a nearly
constant switching frequency over a wide input/output
voltage range. This activity is diagrammed in Figure 1.
The peak inductor current, at which ICMP resets the SR
latch, is controlled by the voltage on ITH. ITH is in turn
controlled by several loops, depending upon the situation
at hand. The average current control loop converts the
voltage between CSP and BAT to a representative current.
Error amp CA2 compares this current against the desired
current programmed by RPROG at the PROG pin and
OFF
TGATE
ON
ON
BGATE
OFF
INDUCTOR
CURRENT
tOFF
TRIP POINT SET BY ITH VOLTAGE
Figure 1
40071 F01
40071f
11
11 Page | ||
| Páginas | Total 24 Páginas | |
| PDF Descargar | [ Datasheet LTC4007-1.PDF ] | |
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