Rta8283A (U23, U173); General Description; Features; Pinning - Sharp LC-32LE140E Service Manual

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LC-32LE140
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14. RTA8283A (U23, U173)

14. RTA8283A (U23, U173)

14.1. General Description

14.1. General Description
The RT8283A is a high-efficiency, monolithic synchronous step-down DC/DC converter
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
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
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
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
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
during start-up. The RT8283A also provides output under voltage protection and thermal
shutdown protection. The low current (<3μA) shutdown mode provides output disconnect,
shutdown protection. The low current (<3μA) shutdown mode provides output disconnect,
enabling easy power management in batterypowered systems. The RT8283A is available
enabling easy power management in batterypowered systems. The RT8283A is available
in a SOP-8 package.
in a SOP-8 package.

14.2. Features

14.2. Features
 ±1.5% High Accuracy Feedback Voltage
 ±1.5% High Accuracy Feedback Voltage
 Integrated N-MOSFET Switches
 Integrated N-MOSFET Switches
 Current Mode Control
 Current Mode Control
 Fixed Frequency Operation : 340kHz
 Fixed Frequency Operation : 340kHz
 Output Adjustable from 0.8V to 20V
 Output Adjustable from 0.8V to 20V
 Up to 95% Efficiency
 Up to 95% Efficiency
 Thermal Shutdown Protection
 Thermal Shutdown Protection

14.3. Pinning

14.3. Pinning
Pin No.
4, 9 (Exposed
15. MP1583 (U174)
VIN Input Supply pin for controller. Put small
decoupling ceramic near this pin.
optimized over a wide range of loads and outp
decoupling ceramic near this pin.
EN Enable input, "High" enables MP2012. EN is
provides protection against shorted outputs an
EN Enable input, "High" enables MP2012. EN is
pulled to GND with 1Meg internal resistor.
pulled to GND with 1Meg internal resistor.
during start-up. The RT8283A also provides ou
shutdown protection. The low current (<3μA) sh
enabling easy power management in batterypo
in a SOP-8 package.
Pin
Name
1 BOOT
2 VIN
3 SW
GND
Pad)
5
FB
6
COMP
7 EN
8 SS
14.2. Features
 ±1.5% High Accuracy Feedback Volta
 Integrated N-MOSFET Switches
 Current Mode Control
 Fixed Frequency Operation : 340kHz
 Output Adjustable from 0.8V to 20V
 Up to 95% Efficiency
 Thermal Shutdown Protection
14.3. Pinning
Description
Bootstrap for high-side gate driver. Connect a 0.1μF or
greater ceramic capacitor from BOOT to SW pins.
Input Supply 4.5V to 23V. Must bypass with a suitably
large ceramic capacitor.
Phase Node--Connect to external L-C filter..
Ground.
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.
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.
Enable Input Pin. Logic high enables the converter; a
logic low forces the RT8253A into shutdown mode.
Attach this pin to VIN with a 100kΩ pull up resistor for
automatic startup.
Soft-Start Control Input. SS controls the soft-start period.
Connect a capacitor from SS to GND to set the soft-start
period. A 0.1μF capacitor sets the soft-start period to
13.5ms.
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