Vicor Corp.

Tel: 800-735-6200, 978-470-2900 Fax: 978-475-6715

HAM, High-Boost Harmonic Attenuation Module

Rev. 2.5

Page 7 of 10

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Outputs

DC-DC Converter(s)

Rectified Line

Enable Output (E/O)

DC Output

of HAM

Power OK (P/OK)

AC Mains

120 Vrms

Boost Voltage

250 Vdc

280 Vdc

Off at 250 Vdc

Off at 270 Vdc

270 Vdc

25 ms

10 ms

Off below 250 Vdc

Figure 9 — Start up / shut down timing diagram

Figure 7 — Power OK (P/OK)

LOGIC

P/OK

–OUT

+OUT

E/O

S

G

D

A/S

LOGIC

E/O

–OUT

+OUT

P/OK

A/S

S

G

D

Figure 8 — Enable / Output (E/O)

P/OK

Power OK is a monitor signal that indicates the status of the

AC mains and the DC output voltage of the HAM. P/OK is

asserted (active low) when the output bus voltage is within

normal operating range (>270 Vdc) and 20 – 25 ms after DC-DC

converters are enabled by the E/O signal of the HAM. This

provides sufficient time for the converters to turn on and their

output(s) to stabilize prior to P/OK being asserted, (Figure 9).

For momentary interruptions of AC power, the HAM will

provide at least 16 ms of ride through or hold up time (with

1,000 µF output capacitor). On loss of power or brownout,

(when the HAM output voltage drops below 270 Vdc) the

P/OK signal will go to an open circuit state (Figure 7),

signaling an impending loss of input power to the converter

modules. P/OK will provide power fail warning at least 1 ms

prior to converter shut down. When the HAM output voltage

drops below 250 Vdc the converters are disabled via Enable

Output (E/O).

PIN FUNCTION / DESCRIPTION (CONT.)