Si9183
Vishay Siliconix
www.vishay.com
10
Document Number: 71258
S-51147—Rev. G, 20-Jun-05
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.
V
IN
V
IN
is the input supply pin. The bypass capacitor for this pin
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.
V
OUT
V
OUT
is the output voltage of the regulator. Connect a bypass
capacitor from V
OUT
to ground. The output capacitor can be
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
Ground is the common ground connection for V
IN
and V
OUT
.
It is also the local ground connection for C
BP
, ADJ, and SD.
ADJ
For the adjustable output version, use a resistor divider R1 and
R2, connect R1 from V
OUT
to ADJ and R2 from ADJ to ground.
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 +
ǒ
V
OUT
* V
ADJ
Ǔ
R2
V
ADJ
V
ADJ
is nominally 1.215 V.
SHUTDOWN (SD)
SD
controls the turning on and off of the Si9183. V
OUT
is
guaranteed to be on when the SD
pin voltage equals or is
greater than 1.2 V. V
OUT
is guaranteed to be off when theSD
pin voltage equals or is less than 0.4 V. During shutdown
mode, the Si9183 will draw less than 1-mA current from the
source. To automatically turn on V
OUT
whenever the input is
applied, tie the SD
pin to V
IN
.
C
BP
For low noise application, connect a high frequency ceramic
capacitor from C
BP
to ground. A 0.01-mF or a 0.1-mF X5R or
X7R is recommended.
Vishay Siliconix maintains worldwide manufacturing capability. Products may be manufactured at one of several qualified locations. Reliability data for Silicon Technology and
Package Reliability represent a composite of all qualified locations. For related documents such as package/tape drawings, part marking, and reliability data, see
http://www.vishay.com/ppg?71258
.
