SEMP8965-30 Просмотр технического описания (PDF) - Secos Corporation.
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SEMP8965-30 Datasheet PDF : 11 Pages
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Elektronische Bauelemente
VREF
VREF
VVOINUT
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SEMP8965
Fast Ultra High-PSRR, Low Noise, Low-Dropout,
600 mA Micropower CMOS Linear Regulator
R1
R2
Figure 2. Simplified Regulator Topology
OUTPUT CAPACITOR
The SEMP8965 is specially designed for use with ceramic output capacitors of as low as 2.2µF to take advantage of the savings in cost and space
as well as the superior filtering of high frequency noise. Capacitors of higher value or other types may be used, but it is important to make sure its
equivalent series resistance (ESR) be restricted to less than 0.5Ω. The use of larger capacitors with smaller ESR values is desirable for
applications involving large and fast input or output transients, as well as for situations where the application systems are not physically located
immediately adjacent to the battery power source. Typical ceramic capacitors suitable for use with the SEMP8965 are X5R and X7R. The X5R and
the X7R capacitors are able to maintain their capacitance values to within ±20% and ±10%, respectively, as the temperature increases.
No-Load Stability
The SEMP8965 is capable of stable operation during no-load conditions, a mandatory feature for some applications such as CMOS RAM
keep-alive operations.
INPUT CAPACITOR
A minimum input capacitance of 1µF is required for SEMP8965. The capacitor value may be increased without limit. Improper workbench set-ups
may have adverse effects on the normal operation of the regulator. A case in point is the instability that may result from long supply lead inductance
coupling to the output through the gate capacitance of the pass transistor. This will establish a pseudo LCR network, and is likely to happen under
high current conditions or near dropout. A 10µF tantalum input capacitor will dampen the parasitic LCR action thanks to its high ESR. However,
cautions should be exercised to avoid regulator short-circuit damage when tantalum capacitors are used, for they are prone to fail in short-circuit
operating conditions.
COMPENSATION (NOISE BYPASS) CAPACITOR
Substantial reduction in the output voltage noise of the SEMP8965 is accomplished through the connection of the noise bypass capacitor CC (33nF
optimum) between pin 6 and the ground. Because pin 6 connects directly to the high impedance output of the bandgap reference circuit, the level of
the DC leakage currents in the CC capacitors used will adversely reduce the regulator output voltage. This sets the DC leakage level
as the key selection criterion of the CC capacitor types for use with the SEMP8965. NPO and COG ceramic capacitors typically offer very low
leakage. Although the use of the CC capacitors does not affect the transient response, it does affect the turn-on time of the regulator. Tradeoff
exists between output noise level and turn-on time when selecting the CC capacitor value.
http://www.SeCoSGmbH.com/
01-June-2002 Rev. A
Any changes of specification will not be informed individually.
Page 10 of 11
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