|
|
PDF LTC3552 Data sheet ( Hoja de datos )
| Número de pieza | LTC3552 | |
| Descripción | Standalone Linear Li-Ion Battery Charger and Dual Synchronous Buck Converter | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de LTC3552 (archivo pdf) en la parte inferior de esta página. Total 24 Páginas | ||
|
No Preview Available !
LTC3552
FEATURESwww.datasheet4u.com
Standalone Linear Li-Ion
Battery Charger and Dual
Synchronous Buck Converter
DESCRIPTIO
■ Programmable Charge Current Up to 950mA
■ Complete Linear Charger and Dual DC/DC
Regulator
■ Buck Converter Output Voltage from 0.6V to 5V
■ No MOSFET, Sense Resistor or Blocking Diode
Required
■ Thermal Regulation Maximizes Charge Rate
Without Risk of Overheating*
■ Charges Directly from a USB Port
■ Programmable Charge Current Termination
■ Preset 4.2V Charge Voltage with ±1% Accuracy
■ Charge Current Monitor Output for Gas Gauging*
■ Automatic Recharge
■ Charge Status Output
■ “Power Present” Output
■ 2.9V Trickle Charge Threshold
■ Soft-Start Limits Inrush Current
■ Low Quiescent Current Buck Converter (40µA)
■ Current Mode Operation, Constant Frequency (2.25MHz)
■ Low Profile (5mm × 3mm × 0.75mm) DFN Package
U
APPLICATIO S
■ Cellular Telephones, PDAs, MP3 Players
■ Bluetooth Applications
The LTC®3552 is a complete constant-current/constant-
voltage linear charger with a dual DC/DC converter for
single cell lithium-ion batteries. Its DFN package and low
external component count make the LTC3552 ideally suited
for portable applications. Furthermore, the LTC3552 is
designed to work within USB power specifications.
No external sense resistor or external blocking diode is
required due to the internal MOSFET architecture. The
charge voltage is fixed at 4.2V and the charge current is
programmed with a resistor. The charge cycle terminates
when the charge current drops below the programmed
termination threshold after the final float voltage is reached.
When the input supply (wall adapter or USB supply) is
removed, the LTC3552 enters a low current state dropping
the battery drain current to less than 2µA. Thermal regula-
tion maximizes charge rate without risk of overheating.
The synchronous step-down switching regulators gen-
erate adjustable output voltages from 5V down to 0.6V.
The switching frequency is set at 2.25MHz, allowing the
use of small surface mount inductors and capacitors.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
*Protected by U.S. patents, including 6522118, 6700364, 5481178, 6580258, 6304066,
6127815, 6498466, 6611131.
TYPICAL APPLICATIO
Single Cell Li-Ion Battery Charger with
C/5 Termination and Dual DC/DC Converter
VIN
4.5V TO
6.5V
VOUT2
2.5V/
400mA
1µF
COUT2
4.7µF
CER
619Ω
1.24k
4.7µH
LTC3552
VIN RUN1
ITERM
RUN2
PROG
BAT
CHRG
PWR
EN
SW2
VCC
POR
MODE/SYNC
SW1
CFF2
68pF
R4
887k
R3
280k
VFB2
GND VFB1
800mA
+
10µF
2.2µH
R2
604k
R1
301k
CFF1
33pF
4.2V
1-CELL
Li-Ion
BATTERY
VOUT1
1.8V/
800mA
COUT1
10µF
CER
3552 TA01
Efficiency Curve/
Power Loss of Regulators
100
1000
95
90 EFFICIENCY
100
85
80
POWER LOSS
75
10
70 1
65
60
1
0.1
10 100 1000
LOAD CURRENT (mA)
VCC = 3.3V, VOUT = 1.8V
Burst Mode OPERATION
3552 TA01b
REGULATOR 1, NO LOAD ON REGULATOR 2
3552f
1
1 page  
LTC3552
TYPICAL PERFOR A CE CHARACTERISTICS TA = 25°C Unless Otherwise Specified.
Battery Charger
⎯C⎯H⎯R⎯G Pin I-V Curve
www.datash(ePeut4llu-.Dcoomwn State)
30
TA = –40°C
25
TA = 25°C
⎯P⎯W⎯R Pin I-V Curve
(Pull-Down State)
30
TA = –40°C
25
TA = 25°C
Charge Current vs Battery Voltage
600
500
20
TA = 90°C
20
TA = 90°C
400
15 15
300
10
5
0
01
VIN = 5V
VBAT = 4V
2 34 5
VCHRG (V)
67
3552 G07
10
5
0
01
VIN = 5V
VBAT = 4V
2 34 5
VPWR (V)
67
3552 G08
200
100
0
2.4 2.7
VIN = 5V
θJA = 40°C/W
RPROG = 2k
3 3.3 3.6 3.9 4.2 4.5
VBAT (V)
3552 G09
Trickle Charge Current
vs Temperature
60
VIN = 5V
VBAT = 2.5V
50
RPROG = 2k
40
30
20
RPROG = 10k
10
0
–50 –25 0
25 50
TEMPERATURE (°C)
75 100
3552 G09a
Trickle Charge Current vs VIN
60
VBAT = 2.5V
50
RPROG = 2k
40
30
20
RPROG = 10k
10
0
4 4.5 5 5.5 6
VIN (V)
6.5 7
3552 G09b
Trickle Charge Threshold Voltage
vs Temperature
3.000
VIN = 5V
2.975 RPROG = 10k
2.950
2.925
2.900
2.875
2.850
2.825
2.800
–50 –25
0
25 50 75 100
TEMPERATURE (°C)
3552 G09c
Charge Current vs VIN
600
RPROG = 2k
500
400
VBAT = 4V
300 θJA = 40°C/W
200
RPROG = 10k
100
Charge Current
vs Ambient Temperature
600
ONSET OF THERMAL REGULATION
500
RPROG = 2k
400
VIN = 5V
300 VBAT = 4V
θJA = 40°C/W
200
RPROG = 10k
100
0
4 4.5 5 5.5 6 6.5 7 7.5 8
VIN (V)
3552 G10
0
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
3552 G11
3552f
5
5 Page 
U
OPERATIO
Charge Current Soft-Start
The charger includes a soft-start circuit to minimize the
wwwi.ndarutasshheceut4rur.ecnomt at the start of a charge cycle. When a charge
cycle is initiated, the charge current ramps from zero to
full-scale current over a period of approximately 100µs.
This has the effect of minimizing the transient current load
on the power supply during start-up.
Thermal Limiting
An internal thermal feedback loop reduces the pro-
grammed charge current if the die temperature attempts
to rise above a preset value of approximately 120°C. This
feature protects the charger from excessive temperature
and allows the user to push the limits of the power handling
capability of a given circuit board without risk of damag-
ing the charger. The charge current can be set according
to typical (not worst case) ambient temperature with the
assurance that the charger will automatically reduce the
current in worst-case conditions. DFN package power
considerations are discussed further in the Applications
Information section.
Undervoltage Lockout (UVLO)
An internal undervoltage lockout circuit monitors the in-
put voltage and keeps the charger in shutdown mode
until VIN rises above the undervoltage lockout thresh-
old. The UVLO circuit has a hysteresis of 200mV.
Also, to protect against reverse current in the power
MOSFET, the UVLO circuit keeps the charger in shutdown
mode if VIN falls to within 30mV of the BAT voltage. If the
UVLO comparator is tripped, the charger will not come
out of shutdown mode until VIN rises 100mV above the
BAT voltage.
Manual Shutdown
At any point in the charge cycle, the charger can be put
into shutdown mode by driving the ⎯E⎯N pin high. This re-
duces the battery drain current to less than 2µA and the
VIN supply current to less than 50µA. When in shutdown
mode, the ⎯C⎯H⎯R⎯G pin is in the high impedance state. A new
charge cycle can be initiated by driving the ⎯E⎯N pin low. An
internal resistor pull-down on this pin forces the charger
to be enabled if the pin is allowed to float.
LTC3552
DUAL SWITCHING REGULATOR
The regulators use a current mode architecture with a
constant operating frequency of 2.25MHz. Both regula-
tors share the same clock and run in-phase. To suit a
variety of applications, the MODE/SYNC pin allows the
user to choose between low noise or high efficiency.
The output voltages are set by external resistive dividers
returned to the VFB pins. An error amplifier compares the
divided output voltage (VFB) with a reference voltage of
0.6V and adjusts the peak inductor current accordingly.
An undervoltage comparator will pull the ⎯P⎯O⎯R output
low if VFB is less than 91.5% of the reference voltage.
The ⎯P⎯O⎯R output will go high after 262,144 clock cycles
(about 117ms in pulse-skipping mode) of achieving
regulation.
Main Regulator Control Loop
During normal operation, the top power switch (P-chan-
nel MOSFET) is turned on at the beginning of a clock
cycle when the feedback voltage is below the reference
voltage. The current into the inductor and the load in-
creases until the current limit is reached. The switch turns
off and energy stored in the inductor flows through the
bottom switch (N-channel MOSFET) into the load until the
next clock cycle. The peak inductor current is controlled
by the internally compensated ITH voltage, which is the
output of the error amplifier. This amplifier compares
VFB to the 0.6V reference (see Block Diagram). When
the load current increases, the VFB voltage decreases
slightly below the reference. This decrease causes the
error amplifier to increase the ITH voltage until the aver-
age inductor current matches the new load current. The
main control loop can be shut down by pulling the RUN
pin to ground.
Low Load Current Operation
The MODE/SYNC pin provides two modes of operation
at low currents. Both modes automatically switch from
continuous operation to the selected mode when the load
current is low. For highest efficiency at low current,
connecting the MODE/SYNC pin to VCC makes the regu-
lator operate in Burst Mode, where the PMOS switch
operates intermittently based on load demand with a
3552f
11
11 Page | ||
| Páginas | Total 24 Páginas | |
| PDF Descargar | [ Datasheet LTC3552.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| LTC3550 | Dual Input USB/AC Adapter Li-Ion Battery Charger | Linear Technology |
| LTC3550-1 | Dual Input USB/AC Adapter Li-Ion Battery Charger | Linear Technology |
| LTC3552 | Standalone Linear Li-Ion Battery Charger and Dual Synchronous Buck Converter | Linear Technology |
| LTC3552-1 | Standalone Linear Li-Ion Battery Charger and Dual Synchronous Buck Converter | 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 |