G9131 Просмотр технического описания (PDF) - Global Mixed-mode Technology Inc
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G9131 Datasheet PDF : 10 Pages
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Global Mixed-mode Technology Inc.
G9131
Applications Information
Capacitor Selection and Regulator Stability
Normally, use a 1µF capacitor on the input and a 1µF
capacitor on the output of the G9131. Larger input ca-
pacitor values and lower ESR provide better sup-
ply-noise rejection and transient response. For stable
operation over the full temperature range, with load
currents up to 120mA, a minimum of 1µF is recom-
mended.
Power-Supply Rejection and Operation from
Sources Other than Batteries
The G9131 is designed to deliver low dropout voltages
and low quiescent currents in battery powered sys-
tems. Power-supply rejection is 47dB at low frequen-
cies the output capacitor is the major contributor to the
rejection of power-supply noise.
When operating from sources other than batteries,
improve supply-noise rejection and transient response
by increasing the values of the input and output ca-
pacitors, and using passive filtering techniques.
Load Transient Considerations
The G9131 load-transient response graphs show two
components of the output response: a DC shift of the
output voltage due to the different load currents, and
the transient response. Typical overshoot for step
changes in the load current from 0mA to 300mA is
10mV. Increasing the output capacitor's value and
decreasing its ESR attenuates transient spikes.
Input-Output (Dropout) Voltage
A regulator's minimum input-output voltage differential
(or dropout voltage) determines the lowest usable
supply voltage. In battery-powered systems, this will
determine the useful end-of-life battery voltage. Be-
cause the G9131 use a P-channel MOSFET pass
transistor, their dropout voltage is a function of RDS(ON)
multiplied by the load current.
IN
－
ERROR
AMP
＋
OVER CURRENT
PROTECT & DYNAMIC
FEEDBACK
OVER TEMP.
PROTECT
1.25V
Vref
GND
Figure 1. Functional Diagram
P
OUT
R1
R2
Ver: 1.6
Dec 22, 2005
TEL: 886-3-5788833
http://www.gmt.com.tw
8
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