DER-99

Set Top Box 17.4 W Power Supply

September 12, 2005

Page 21 of 29

Power Integrations

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9.6

Hold-Up Time and Power Good

Figure 14 – Hold-Up time. At Full Output Load. Top Trace is the AC Line Voltage, Middle trace 5V output,

Bottom Trace is the HV DC bus. AC voltage is 160 Vac.

Note: The AC line was interrupted for about 28ms. The power supply maintained output

regulation for the whole time the AC line was off.

AC Off

Power good

3V output

Figure 15

Notes:

• 3V output drops out >20 mS after AC turns off. (Spec is >16.7 mS)

• Power good goes down 10 mS before 3V (Spec is > 5mS)

• 160Vac is the worst case. Higher voltages show even greater holdup time.