SC8863 Ver la hoja de datos (PDF) - Semtech Corporation

Número de pieza

componentes Descripción

Fabricante

SC8863

150mA Ultra Low Dropout, Low Noise Regulator

Semtech Corporation 

SC8863

POWER MANAGEMENT

Typical Characteristics (Cont.)

Sense/Select Threshold vs.

Junction Temperature

80

VIN = 3.6V

70

60

50

40

Output Spectral Noise Density

vs. Frequency

10

SC8863-2.8

VIN = 3.6V

IOUT = 50mA

TJ = 25°C

1

COUT = 1µF

0.1

30

20

-50

-25

0

25

50

75

100

125

TJ (°C)

0.01

0.1

COUT = 100µF

1

10

100

f (kHz)

Applications Information

Theory Of Operation

output noise and improve the overall transient response.

The SC8863 is intended for applications where very low

dropout voltage, low supply current and low output noise

are critical. It provides a very simple, low cost solution

that uses very little pcb real estate. Fixed output voltage

options require the use of only two external capacitors

for operation.

Each voltage option has both fixed and adjustable

output voltage modes. Grounding the SET pin (pulling it

below the Sense/Select threshold of 55mV) will connect

the internal resistor divider to the error amplifier

resulting with the internally preset output voltage. If SET

is pulled above this threshold, then the Sense/Select

switch will connect the SET pin to the error amplifier. The

output will be regulated such that the voltage at SET will

equal VSET, the SET reference voltage (typically 1.250V).

Input capacitor: Semtech recommends the use of a 1µF

ceramic capacitor at the input. This allows for the device

being some distance from any bulk capacitance on the

rail. Additionally, input droop due to load transients is

reduced, improving load transient response.

Component Selection - Externally Set Output

Please refer to Figure 1 below. The output voltage can

be externally adjusted anywhere within the range from

1.25V to (V - V ). The output voltage will be in

IN(MIN)

D(MAX)

accordance with the following equation:

VOUT

= 1.250 • 1+



R1 

R2 

An active high enable pin (EN) is provided to allow the

customer to shut down the part and enter an extremely

low power Off-state. A logic Low signal will reduce the

supply current to 0.1nA.

Component Selection - General

Output capacitor: Semtech recommends a minimum

capacitance of 1µF at the output with an equivalent

series resistance (ESR) of <1Ω over temperature.

Ceramic capacitors are ideal for this application.

Increasing the bulk capacitance will further reduce

C1

1uF Ceramic

U1

3 IN

SC8863

OUT 4

1 EN GND SET 5

2

R1

R2

10k

C2

2.2uF Ceramic

Figure 1: Externally set output

 2005 Semtech Corp.

7

www.semtech.com

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