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PDF LTC1730-4 Data sheet ( Hoja de datos )
| Número de pieza | LTC1730-4 | |
| Descripción | Lithium-Ion Battery Pulse Charger | |
| Fabricantes | Linear | |
| Logotipo |  |
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FEATURES
s Complete Pulse Charger for 1-Cell Lithium-Ion
Batteries
s Sense Resistor Limits Maximum Current for Safety
s 1% Float Voltage Accuracy
s End-of-Charge (C/10) Detection Output
s Programmable Charge Termination Timer
s Internal 0.35Ω NMOS Switch
s No Blocking Diode Required
s SEL Pin to Set Either 4.1V or 4.2V/Cell (LTC1730-4)
s Low-Battery Drain (1µA Max) when Input Supply Is
Removed
s Battery Temperature Sensing and Charge
Qualification
s Automatic Trickle Charge for Low-Battery
s Automatic Battery Refresh
U
APPLICATIO S
s Standalone Lithium-Ion Battery Charger
s Handheld Computers
s Cellular Telephones
LTC1730-4/LTC1730-4.2
Lithium-Ion Battery
Pulse Charger with
Overcurrent Protection
DESCRIPTIO
The LTC®1730 is a complete pulse charger for 1-cell
lithium-ion batteries. When charging a depleted cell, the
internal MOSFET is fully on allowing the current limited
input power source to provide charge current to the
battery, virtually eliminating heat generation in the charger.
As the battery accepts charge and approaches the pro-
grammed voltage, the internal MOSFET begins switching
off and on with the duty cycle gradually decreasing as the
battery approaches a fully charged condition. A program-
mable timer ends the charge cycle. The end-of-charge
condition is indicated at the CHRG pin when the average
charge current falls to C/10. Removing the input voltage
puts the LTC1730 into a sleep mode, dropping the battery
current drain to less than 1µA (maximum).
An external sense resistor limits the maximum charge
current as a safety precaution against a user connecting a
wall adapter with the incorrect or no current limit. The
internal MOSFET prevents reverse battery current from
flowing if the input voltage is shorted to ground, eliminat-
ing the need for a blocking diode.
The LTC1730-4 is available in the 16-pin SSOP package
and the LTC1730-4.2 is available in the 8-pin SO package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
1A, Single Cell 4.2V Li-Ion Battery Charger (8-Pin Package)
VIN = 4.5V TO 12V
WITH 1A CURRENT LIMIT
CHARGE STATUS
2
R1
1k
R3
4.1k D3
VCC
LTC1730ES8-4.2
7
GATE
3
CHRG
T
*NTC: DALE NTHS-1206N02
R4
10k
NTC*
1
SENSE
68
NTC/SHDN BAT
TIMER
CTIMER
0.1µF
5
GND
4
R2
10k
C3
0.047µF
RSENSE
0.05Ω
0.022µF
1-CELL
Li-Ion
BATTERY
4.7Ω
C1
1µF
1730 TA01
sn1730 1730fs
1
1 page  
LTC1730-4/LTC1730-4.2
PI FU CTIO S
LTC1730ES8-4.2
SENSE (Pin 1): Maximum Overcurrent Sense Input. A
sense resistor (RSENSE) should be connected from VCC to
the SENSE pin. When the voltage drop across RSENSE
exceeds 100mV, the pass transistor immediately turns off
and turns back on after a 400ms time-out period (CTIMER
= 0.1µF). The on-off cycle will continue, as long as the
overcurrent condition persists or until the timer runs out.
If overcurrent protection is not needed, short SENSE to
VCC.
VCC (Pin 2): Positive Input Supply Voltage (4.5V ≤ VCC ≤
13.2V). Bypass this pin with a 1µF capacitor in series with
a 4.7Ω resistor. An RC network from the VCC pin to the
GATE pin is also required. The capacitor controls the slew
rate at the VCC pin, while the resistor limits the inrush
current when the input voltage is first applied. When the
pass transistor turns on, VCC ramps down in a controlled
manner, with a slope equal to 10µA/C. When the pass
transistor turns off, VCC ramps up with a slope of 40µA/C.
CHRG (Pin 3): Open-Drain Charge Status Output. When a
depleted battery is being charged, the CHRG pin is pulled
to ground by an N-MOSFET capable of driving an LED.
Once the duty cycle at the GATE pin drops below 10%, the
N-MOSFET turns off and a weak 40µA current source to
ground turns on to indicate a near end-of-charge (C/10)
condition. When a time-out occurs or the input supply is
removed, the CHRG pin goes high impedance.
GND (Pin 4): Electrical Ground Connection and provides
a thermal path from the IC to the PC board copper. Use
large copper pads and traces for maximum heat transfer.
TIMER (Pin 5): Timer Set Pin. The timer period is set by a
capacitor (CTIMER) to ground. The timer period is:
tTIMER = (CTIMER • 3Hr)/(0.1µF). The minimum ON time,
OFF time and the overcurrent time-out period are all set by
the same timer period.
NTC/SHDN (Pin 6): Input to the NTC (Negative Tempera-
ture Coefficient) Thermistor Monitoring and Shutdown
Circuitry. With an external 10kΩ NTC thermistor to ground
and a 1% resistor to VCC, this pin can sense the tempera-
ture of the battery pack and stop charging when the
temperature is out of range. When the voltage at this pin
drops below 0.5 • VCC, or 2V at hot temperature or rises
above 0.875 • VCC, or 3.5V at cold (with VCC = 4V), the
charge cycle is suspended and the internal timer is frozen.
The CHRG pin output status is not affected in this hold
state.
When this pin is pulled below 50mV, the IC goes into the
shutdown mode. The charging stops (the GATE pin is
pulled to ground) the timer is reset and the CHRG pin goes
into a high impedance state.
GATE (Pin 7): Gate Drive Output Pin for Internal and
External Pass Transistors. An external N-MOSFET transis-
tor can be connected in parallel with the internal transistor
to reduce the on-resistance for higher charge current. In
this case, an external blocking diode is required to prevent
damage to the battery if VCC is shorted to ground. A 10µA
current source pulls this pin up to the charge pump
potential when turned on and a 40µA current source pulls
it down to ground to turn it off. If an overcurrent condition
is detected, the GATE pin is immediately pulled to ground.
A series RC network from the GATE to the VCC pin is
required to control the slew rate at the VCC pin when the
switch is turned on or off. The slew rate control prevents
excessive current from the capacitor located in the wall
adapter from flowing into the battery when the pass
transistor is turned on. The voltage at this pin is internally
clamped to 12V above the BAT pin.
BAT (Pin 8): Battery Sense Input Pin. This pin is clamped
to 4.7V if the battery is disconnected while charging. An
internal resistor divider presets the final float voltage to
4.2V.
If the voltage at the BAT pin drops 150mV below final float
voltage after the charge cycle has ended, the timer resets
and a new charge cycle begins.
LTC1730EGN-4
GND (Pins 1, 8, 9, 16): Refer to LTC1730ES8-4.2
SENSE (Pin 2): Refer to LTC1730ES8-4.2
VCC (Pin 3): Refer to LTC1730ES8-4.2
ACPR (Pin 4): Wall Adapter Present Open-Drain Output.
When the input voltage (wall adapter) is applied to the
LTC1730, this pin is pulled to ground by an internal
sn1730 1730fs
5
5 Page 
APPLICATIO S I FOR ATIO
charge time, the battery is considered defective. The
charger turns off and the FAULT pin is pulled low. This
pin will stay low until the LTC1730 is reset by either
removing the input power supply or momentarily
LTC1730-4/LTC1730-4.2
shutting down the charger. After reset, the charger is
back in the charge mode and the FAULT pin becomes
high impedance again.
PACKAGE DESCRIPTIO
GN Package
16-Lead Plastic SSOP (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1641)
0.007 – 0.0098
(0.178 – 0.249)
0.015
(0.38
±
±
0.004
0.10)
×
45°
0° – 8° TYP
0.016 – 0.050
(0.406 – 1.270)
* DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
0.053 – 0.068
(1.351 – 1.727)
0.008 – 0.012
(0.203 – 0.305)
0.004 – 0.0098
(0.102 – 0.249)
0.189 – 0.196*
(4.801 – 4.978)
16 15 14 13 12 11 10 9
0.009
(0.229)
REF
0.0250
(0.635)
BSC
0.229 – 0.244
(5.817 – 6.198)
0.150 – 0.157**
(3.810 – 3.988)
GN16 (SSOP) 1098
1 234 5678
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
0.010
(0.254
–
–
0.020
0.508)
×
45°
0.008 – 0.010
(0.203 – 0.254)
0.053 – 0.069
(1.346 – 1.752)
0°– 8° TYP
0.016 – 0.050
(0.406 – 1.270)
0.014 – 0.019
(0.355 – 0.483)
TYP
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
0.004 – 0.010
(0.101 – 0.254)
0.189 – 0.197*
(4.801 – 5.004)
8 765
0.050
(1.270)
BSC
0.228 – 0.244
(5.791 – 6.197)
0.150 – 0.157**
(3.810 – 3.988)
1 2 34
SO8 1298
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
sn1730 1730fs
11
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet LTC1730-4.PDF ] | |
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