SG117 Просмотр технического описания (PDF) - Microsemi Corporation

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SG117

Positive Adjustable Linear Voltage Regulators

Microsemi Corporation 

SG117 / 217 / 317 / 117A / 217A / 317A

TM

®

1.5A Three Terminal Adj. Voltage Regulator

APPLICATION INFORMATION (CONTINUED)

BYPASS CAPACITORS

Input bypassing using a 1μF tantalum or 25μF electrolytic is

recommended when the input filter capacitors are more than 5

inches from the device. A 0.1µF bypass capacitor on the

ADJUST pin is required if the load current varies by more than

1A/µsec. Improved ripple rejection (80dB) can be

accomplished by adding a 10μF capacitor from the adjust pin

to ground. For improved AC transient response and to prevent

the possibility of oscillation due to unknown reactive load, a

1μF capacitor is also recommended at the output. Because of

their low impedance at high frequencies, the best type of

capacitor to use is solid tantalum.

Figure 22 – 5V Regulator with Shut Down

Figure 20 – Remote Sensing

Figure 23 – 21V Programming Supply for UV Prom/ EEPROM

Figure 21 – Improving Ripple Rejection

LOAD REGULATION

Because the SG117A is a three-terminal device, it is not

possible to provide true remote load sensing. Load regulation

will be limited by the resistance of the wire connecting the

regulator to the load. For the data sheet specification,

regulation is measured at the bottom of the package. Negative

side sensing is a true Kelvin connection, with the bottom of the

output divider returned to the negative side of the load.

Although it may not be immediately obvious, best load

regulation is obtained when the top of the divider is connected

directly to the case, not to the load. This is illustrated in Figure

18. If R1 were connected to the load, the effective resistance

between the regulator and the load would be

R

P

• ⎜⎜⎝⎛

R +R

2

1

R

1

⎟⎟⎠⎞, R P

=

Parasitic Line Resistance

Connected as shown, RP is not multiplied by the divider

ratio. RP is about 0.004Ω per foot using 16 gauge wire. This

translates to 4mV/ft. at 1A load current, so it is important to

keep the positive lead between regulator and load as short as

possible.

Figure 24 – 2816 EEPROM Supply Programmer for Read / Write

Control

Figure 25 – Temperature Compensated Lead Acid Battery

Charger

Copyright © 1994

Rev. 1.3, 2006-02-08

Microsemi

Integrated Products Division

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

Page 8

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