|
|
PDF LTC4001 Data sheet ( Hoja de datos )
| Número de pieza | LTC4001 | |
| Descripción | 2A Synchronous Buck Li-Ion Charger | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de LTC4001 (archivo pdf) en la parte inferior de esta página. Total 20 Páginas | ||
|
No Preview Available !
LTC4001
2A Synchronous
Buck Li-Ion Charger
FEATURES
■ Low Power Dissipation
■ 2A Maximum Charge Current
■ No External MOSFETs, Sense Resistor or Blocking
Diode Required
■ Remote Sensing at Battery Terminals
■ Programmable Charge Termination Timer
■ Preset 4.2V Float Voltage with ±0.5% Accuracy
www■.DaPtraoSghreaemt4mU.caobmle Charge Current Detection/Termination
■ Automatic Recharge
■ Thermistor Input for Temperature Qualified Charging
■ Compatible with Current Limited Wall Adapters
■ Low Profile 16-Lead (4mm × 4mm) QFN Package
U
APPLICATIO S
■ Handheld Battery-Powered Devices
■ Handheld Computers
■ Charging Docks and Cradles
■ Digital Cameras
■ Smart Phones
DESCRIPTIO
The LTC®4001 is a 2A Li-Ion battery charger intended for
5V wall adapters. It utilizes a 1.5MHz synchronous buck
converter topology to reduce power dissipation during
charging. Low power dissipation, an internal MOSFET and
sense resistor allow a physically small charger that can be
embedded in a wide range of handheld applications. The
LTC4001 includes complete charge termination circuitry,
automatic recharge and a ±1% 4.2V float voltage. Input
short-circuit protection is included so no blocking diode is
required.
Battery charge current, charge timeout and end-of-charge
indication parameters are set with external components.
Additional features include shorted cell detection, tempera-
ture qualified charging and overvoltage protection. The
LTC4001 is available in a low profile (0.75mm) 16-lead
(4mm × 4mm) QFN package.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATIO
2A Single Cell Li-Ion Battery Charger
1.5µH
VIN
4.5V TO 5.5V
10µF
VINSENSE
PVIN
SW
SENSE
BATSENS
BAT
PGND
CHRG
LTC4001
NTC
FAULT
EN
PROG IDET TIMER
SS GNDSENS
274Ω
0.22µF
0.1µF
+
10µF
4.2V
Li-Ion
4001 TA01a
Power Loss vs VBAT
Charging (PWM Mode)
1.25
1.00
0.75
0.50
0.25
VIN = 5V
2A CHARGER
0
3 3.25
3.5
3.75
VBAT (V)
4 4.25
4001 TA01b
4001f
1
1 page  
TYPICAL PERFOR A CE CHARACTERISTICS
LTC4001
Soft-Start (PWM Mode)
INPUT
CURRENT (IIN)
0.5A/DIV
0
INDUCTOR
CURRENT (IL)
0.5A/DIV 0
SOFT-START
VOLTAGE (VSS)
1V/DIV 0
EN PIN (VEN)
www.Data5SVh/DeIVet04U.com
VBAT = 3.5V
VIN = 5V
2ms/DIV
4001 G09
IDET Threshold vs RIDET for
RPROG = 549Ω
400
CHRG Pin Temperature Fault
Behavior (Detail)
350
300
250 CHRG
1V/DIV
200
150
100
50
TIME (20µs/DIV)
4001 G11
0
300 400 500 600 700 800 900 100011001200
RIDET (Ω)
4001 G10
PI FU CTIO S
BAT (Pin 1): Battery Charger Output Terminal. Connect a
10µF ceramic chip capacitor between BAT and PGND to
keep the ripple voltage small.
SENSE (Pin 2): Internal Sense Resistor. Connect to exter-
nal inductor.
PGND (Pin 3): Power Ground.
GNDSENS (Pin 4): Ground Sense. Connect this pin to the
negative battery terminal. GNDSENS provides a Kelvin
connection for PGND and must be connected to PGND
schematically.
SW (Pin 5): Switch Node Connection. This pin connects to
the drains of the internal main and synchronous power
MOSFET switches. Connect to external inductor.
EN (Pin 6): Enable Input Pin. Pulling the EN pin high places
the LTC4001 into a low power state where the BAT drain
current drops to less than 3µA and the supply current is
reduced to less than 50µA. For normal operation, pull the
pin low.
CHRG (Pin 7): Open-Drain Charge Status Output. When
the battery is being charged, CHRG is pulled low by an
internal N-channel MOSFET. When the charge current
drops below the IDET threshold (set by the RIDET program-
ming resistor) for more than 5milliseconds, the N-channel
MOSFET turns off and a 30µA current source is connected
from CHRG to ground. (This signal is latched and is reset
by initiating a new charge cycle.) When the timer runs out
or the input supply is removed, the current source will be
disconnected and the CHRG pin is forced to a high imped-
ance state. A temperature fault causes this pin to blink.
PVIN (Pin 8): Positive Supply Voltage Input. This pin
connects to the power devices inside the chip. VIN ranges
from 4V to 5.5V for normal operation. Operation down to
the undervoltage lockout threshold is allowed with current
limited wall adapters. Decouple with a 10µF or larger
surface mounted ceramic capacitor.
VINSENSE (Pin 9): Positive Supply Sense Input. This pin
connects to the inputs of all input comparators (UVL, VIN
to VBAT). It also supplies power to the controller portion of
this chip. When the BATSENS pin rises to within 30mV of
VINSENSE, the LTC4001 enters sleep mode, dropping IIN to
50µA. Tie this pin directly to the terminal of the PVIN
decoupling capacitor.
4001f
5
5 Page 
LTC4001
APPLICATIO S I FOR ATIO
The equations for calculating R1 (used in single resistor
programming) differ from the equations for calculating
RPROG and RIDET (2-resistor programming) and reflect the
fact that the current from both the IDET and PROG pins
must flow through a single resistor R1 when a single
programming resistor is used.
CHRG Status Output Pin
When a charge cycle starts, the CHRG pin is pulled to
ground by an internal N-channel MOSFET which is capable
wwwo.Df adtraivSihnegeta4nU.LcoEmD. When the charge current drops below
the end-of-charge (IDET) threshold for at least 4ms, and
the battery voltage is close to the float voltage, the N-channel
MOSFET turns off and a weak 30µA current source to
ground is connected to the CHRG pin. This weak pull-
down remains until the charge cycle ends. After charging
ends, the pin will become high impedance. By using two
different value resistors, a microprocessor can detect
three states from this pin (charging, end-of-charge and
charging stopped). See Figure 2.
To detect the charge mode, force the digital output pin,
OUT, high and measure the voltage on the CHRG pin. The
N-channel MOSFET will pull the pin low even with a 2k pull-
up resistor. Once the charge current drops below the end-
of-charge threshold, the N-channel MOSFET is turned off
and a 30µA current source is connected to the CHRG pin.
The IN pin will then be pulled high by the 2k resistor
connected to OUT. Now force the OUT pin into a high
impedance state, the current source will pull the pin low
through the 390k resistor. When charging stops, the
CHRG pin changes to a high impedance state and the 390k
resistor will then pull the pin high to indicate charging has
stopped.
Charge Termination
Battery charging may be terminated several different ways,
depending on the connections made to the TIMER pin. For
time-based termination, connect a capacitor between the
TIMER pin and GNDSENS (CTIMER = Time(Hrs) 0.0733µF).
Charging may be terminated when charge current drops
below the IDET threshold by tying TIMER to GNDSENS.
Finally, charge termination may be defeated by tying
TIMER to IDET. In this case, an external device can
terminate charging by pulling the EN pin high.
Battery Temperature Detection
When battery temperature is out of range (either too hot or
too cold) charging is temporarily halted and the FAULT pin
is driven high. In addition, if the battery is still charging at
a high rate (greater than the IDET current) when a tem-
perature fault occurs, the CHRG pin NMOS turns on and off
at approximately 50kHz, alternating between a high and
low duty factor at an approximate rate of 1.5Hz (Figure 3).
This provides a low rate visual indication (1.5Hz) when
driving an LED from the CHRG pin while providing a fast
temperature fault indication (20useconds typical) to a
microprocessor by tying the CHRG pin to an interrupt line.
Serrations within this pulse are typically 500ns wide.
VIN VDD
LTC4001
CHRG
R1
390k R2
2k
µPROCESSOR
OUT
IN
4001 F02
Figure 2. Microprocessor Interface
667ms
20µs
4001 F03
Figure 3. CHRG Temperature Fault Waveform
4001f
11
11 Page | ||
| Páginas | Total 20 Páginas | |
| PDF Descargar | [ Datasheet LTC4001.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| LTC4000 | High Voltage High Current Controller | Linear Technology |
| LTC4001 | 2A Synchronous Buck Li-Ion Charger | Linear Technology |
| LTC4001-1 | 2A Synchronous Buck Li-Ion Charger | Linear Technology |
| LTC4002 | Standalone Li-Ion Switch Mode Battery Charger | Linear Technology |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |