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LC-32LE240

LC-40LE240

Name

Description

1 FB Feedback input. An external resistor divider from

the output to GND, tapped to the FB pin sets the

output voltage.

2 GND,

Exposed

Pad

Ground pin. Connect exposed pad to ground

plane for proper thermal performance.

3 SW Switch node to the inductor.

4 PVIN Input supply pin for power FET.

5 VIN Input Supply pin for controller. Put small

decoupling ceramic near this pin.

6 EN Enable input, “High” enables MP2012. EN is

pulled to GND with 1Meg internal resistor.

14. RTA8283A (U23, U173)

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

shutdown protection. The low current (<3μA) shutdown mode provides output disconnect,

enabling easy power management in batterypowered systems. The RT8283A is available

in a SOP-8 package.

14.2. Features

 ±1.5% High Accuracy Feedback Voltage

 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

Pin No.

Name

Description

1 BOOT

Bootstrap for high-side gate driver. Connect a 0.1μF or

greater ceramic capacitor from BOOT to SW pins.

VIN Input Supply 4.5V to 23V. Must bypass with a suitably

large ceramic capacitor.

SW Phase Node--Connect to external L-C filter..

4, 9 (Exposed

Pad)

GND Ground.

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.

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.

EN 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.

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 0.1μF capacitor sets the soft-start period to

13.5ms.

15. MP1583 (U174)

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.

15.2. Features

 3A Output Current

 Programmable Soft-Start

 100mΩ Internal Power MOSFET Switch

 Stable with Low ESR Output Ceramic Capacitors

 Up to 95% Efficiency

 20μA Shutdown Mode

 Fixed 385KHz Frequency

 Thermal Shutdown

 Cycle-by-Cycle Over Current Protection