Sharp LC-22DV240K Service Manual / Parts Guide ▷ View online
45
LC-22DV240
LC-22DS240
LC-22DS240
14.1. General Description
The RT8283A is a high-efficiency, monolithic synchronous step-down DC/DC converter
that can deliver up to 3A output current from a 4.5V to 23V input supply. The RT8283A's
current mode architecture and external compensation allow the transient response to be
optimized over a wide range of loads and output capacitors. Cycle-by-cycle current limit
provides protection against shorted outputs and soft-start eliminates input current surge
during start-up. The RT8283A also provides output under voltage protection and thermal
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that can deliver up to 3A output current from a 4.5V to 23V input supply. The RT8283A's
current mode architecture and external compensation allow the transient response to be
optimized over a wide range of loads and output capacitors. Cycle-by-cycle current limit
provides protection against shorted outputs and soft-start eliminates input current surge
during start-up. The RT8283A also provides output under voltage protection and thermal
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enabling easy power management in batterypowered systems. The RT8283A is available
in a SOP-8 package.
in a SOP-8 package.
14.2. Features
x
±1.5% High Accuracy Feedback Voltage
x
Integrated N-MOSFET Switches
x
Current Mode Control
x
Fixed Frequency Operation : 340kHz
x
Output Adjustable from 0.8V to 20V
x
Up to 95% Efficiency
x
Thermal Shutdown Protection
Pin No.
Pin
Name
Description
1
BOOT
Bootstrap for high-side gate driver. Connect a 0.1
˩F or
greater ceramic capacitor from BOOT to SW pins.
2
VIN
Input Supply 4.5V to 23V. Must bypass with a suitably
large ceramic capacitor.
large ceramic capacitor.
3
SW
Phase Node--Connect to external L-C filter..
4, 9 (Exposed
Pad)
GND
Ground.
5
FB
Feedback Input pin is connected to the converter output.
It is used to set the output of the converter to regulate to
the desired value via an internal res divider. For an
adjustable output, an external res divider is connected to
this pin.
It is used to set the output of the converter to regulate to
the desired value via an internal res divider. For an
adjustable output, an external res divider is connected to
this pin.
6
COMP
Compensation Node. COMP is used to compensate the
regulation Control loop. Connect a series RC network
from COMP to GND. In some cases, an additional
capacitor from COMP to GND is required.
regulation Control loop. Connect a series RC network
from COMP to GND. In some cases, an additional
capacitor from COMP to GND is required.
7
EN
Enable Input Pin. Logic high enables the converter; a
logic low forces the RT8253A into shutdown mode.
$WWDFKWKLVSLQWR9 ,1 ZLWKDNȍ pull up resistor for
logic low forces the RT8253A into shutdown mode.
$WWDFKWKLVSLQWR9 ,1 ZLWKDNȍ pull up resistor for
automatic startup.
8
SS
Soft-Start Control Input. SS controls the soft-start period.
Connect a capacitor from SS to GND to set the soft-start
period. A 0.1
Connect a capacitor from SS to GND to set the soft-start
period. A 0.1
˩F capacitor sets the soft-start period to
13.5ms.
14.3. Pinning
14. RTA8283A (U23, U173)
46
LC-22DV240
LC-22DS240
LC-22DS240
15.1. General Description
The MP1583 is a step-down regulator with a built-in internal Power MOSFET. It achieves
3A of continuous output current over a wide input supply range with excellent load and
line regulation. Current mode operation provides fast transient response and eases loop
stabilization. Fault condition protection includes cycle-by-cycle current limiting and thermal
shutdown. An adjustable soft-start reduces the stress on the input source at start-up. The
MP1583 requires a minimum number of external components, providing a compact
solution.
3A of continuous output current over a wide input supply range with excellent load and
line regulation. Current mode operation provides fast transient response and eases loop
stabilization. Fault condition protection includes cycle-by-cycle current limiting and thermal
shutdown. An adjustable soft-start reduces the stress on the input source at start-up. The
MP1583 requires a minimum number of external components, providing a compact
solution.
15.2. Features
x
3A Output Current
x
Programmable Soft-Start
x
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x
Stable with Low ESR Output Ceramic Capacitors
x
Up to 95% Efficiency
x
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x
Fixed 385KHz Frequency
x
Thermal Shutdown
x
Cycle-by-Cycle Over Current Protection
x
Wide 4.75V to 23V Operating Input Range
x
Output Adjustable from 1.22V to 21V
x
Under-Voltage Lockout
15.3. Pinning
Pin
No.
Pin
Name
Description
1
BOOT
High-Side Gate Drive Bootstrap Input. BS supplies the drive for the
high-side N-Channel MOSFET switch.
high-side N-Channel MOSFET switch.
2
IN
Power Input. Drive IN with a 4.75V to 23V power source.
3
SW
Power Switching Out is the switching node that supplies power to the
output
output
4
GND
Ground.
5
FB
Feedback Input. FB senses the output voltage and regulates it. Drive
FB with a resistive voltage divider from the output voltage. FB
threshold is 1.222V.
FB with a resistive voltage divider from the output voltage. FB
threshold is 1.222V.
6
COMP
Compensation Node is used to compensate the regulation control
loop.
loop.
7
EN
Enable/UVLO. A voltage greater than 2.71V enables operation. For
complete low current shutdown the EN pin voltage needs to be at less
than 900mV. When the voltage on EN exceeds 1.2V, the internal
regulator will be enabled and the soft-start capacitor will begin to
charge. The MP1583 will start switching after the EN pin voltage
reaches 2.71V.
complete low current shutdown the EN pin voltage needs to be at less
than 900mV. When the voltage on EN exceeds 1.2V, the internal
regulator will be enabled and the soft-start capacitor will begin to
charge. The MP1583 will start switching after the EN pin voltage
reaches 2.71V.
8
SS
Soft-Start Control Input. SS controls the soft-start period.
15. MP1583 (U174)
47
LC-22DV240
LC-22DS240
LC-22DS240
16.1. General Description
This P-Channel 2.5V specified MOSFET is produced using Fairchild’s advanced
PowerTrench® process that has been especially tailored to minimize on-state resistance
and yet maintain low gate charge for superior switching performance.
PowerTrench® process that has been especially tailored to minimize on-state resistance
and yet maintain low gate charge for superior switching performance.
These devices have been designed to offer exceptional power dissipation in a very small
footprint for applications where the larger packages are impractical.
footprint for applications where the larger packages are impractical.
16.2. Features
x
0D[U'6 RQ PȍDW9 *6 -4.5 V, ID = -4.0 A
x
0D[U'6 RQ PȍDW9 *6 -2.5 V, ID = -3.2 A
x
Fast switching speed
x
Low gate charge (11nC typical)
x
High performance trench technology for extremely low rDS(on)
x
SuperSOTTM-6 package: small footprint (72% smaller than standard SO-8);
low profile (1 mm thick)
low profile (1 mm thick)
x
Termination is Lead-free and RoHS Compliant
16.3. Pinning
16. FDC642
48
LC-22DV240
LC-22DS240
LC-22DS240
17.1. General Description
This P-Channel 1.8V specified MOSFET uses Fairchild’s low voltage PowerTrench
process. It has been optimized for battery power management applications.
process. It has been optimized for battery power management applications.
17.2. Features
x
–5.5 A, –95'62 1 Pȍ#9*6 –4.5 V
x
5'6 2 1 Pȍ#VGS = –2.5 V
x
5'6 2 1 Pȍ#9 *6 –1.8 V
x
Fast switching speed.
x
High performance trench technology for extremely low RDS(ON)(S)
17.3. Pinning
18.1. SCART (SC1)
17. FDC604P
18. CONNECTORS
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