Si9183

Vishay Siliconix

www.vishay.com

10

Document Number: 71258

S-40593—Rev. E, 29-Mar-04

DETAILED DESCRIPTION

The Si9183 is a low drop out, low quiescent current, linear

regulator family with very fast transient response. It is primarily

designed for battery powered applications where battery run

time is at a premium. The low quiescent current allows

extended standby time while low drop out voltage enables the

system to fully utilize battery power before recharge. The

Si9183 is a very fast regulator with bandwidth exceeding

50 kHz while maintaining low quiescent current at light load

conditions. With this bandwidth, the Si9183 is one of the

fastest LDO available today. The Si9183 is stable with one of

any output capacitor types from 1 mF to 10.0 mF. However,

X5R or X7R ceramic capacitors are recommended for best

output noise and transient performance.

is not critical as long as the input supply has low enough source

impedance. For practical circuits, a 1.0-mF or larger ceramic

capacitor is recommended. When the source impedance is

not low enough and/or the source is several inches from the

Si9183, then a larger input bypass capacitor is needed. It is

required that the equivalent impedance (source impedance,

wire, and trace impedance in parallel with input bypass

capacitor impedance) must be smaller than the input

impedance of the Si9183 for stable operation. When the

source impedance, wire, and trace impedance are unknown,

it is recommended that an input bypass capacitor be used of

a value that is equal to or greater than the output capacitor.

any value from 1.0 mF to 10.0 mF. A ceramic capacitor with

X5R or X7R dielectric type is recommended for best output

noise, line transient, and load transient performance.

GND

ADJ

For the adjustable output version, use a resistor divider R1 and

R2 should be in the 25-kW to 150-kW range for low power

consumption, while maintaining adequate noise immunity.

The formula below calculates the value of R1, given the

desired output voltage and the R2 value,

(1)

R1 +

SHUTDOWN (SD)

guaranteed to be on when the SD pin voltage equals or is

pin voltage equals or is less than 0.4 V. During shutdown

mode, the Si9183 will draw less than 1-mA current from the

For low noise application, connect a high frequency ceramic

X7R is recommended.