Pin Function Description (cont.)
• 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 6). 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 high, 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 the Module Enable. (Figures 7–9)
Applications Notes
•
ThermMates or thermal compound should be used between the
heat sink and baseplate of the HAM, HAMD and BAMD to
insure adequate heat transfer.
•
The HAM output is not isolated from the line input; isolated
probes must be used when making scope measurements.
Protective Features
Over Temperature Shut Down
The HAM incorporates over temperature shut down, and is
designed to shut down when the temperature of the baseplate
exceeds 90°C. The HAM should not be operated for extended
periods above its maximum operating temperature of 85°C.
Short Circuit Protection
The HAM contains output short circuit protection. Operation of
this function does not clear the input fuse and the output will
resume normal operation after removal of the fault. A short
period of time may be required to allow for cooling of an internal
temperature sensor.
Output Over Voltage Protection
The HAM contains output over voltage protection. In the event
the output voltage exceeds approximately 420 Vdc, the boost will
decrease to maintain 420 Vdc on the output. When the peak of
the AC line exceeds 420 V (approximately 293 Vac) the boost
will have been reduced to zero. Beyond this the protection circuit
will be enabled and the output voltage will decrease.
Over current protection is provided by the Vicor DC-DC
converters.
D
LOGIC
G
S
P/OK
E/O
D
LOGIC
-OUT
S
G
-OUT
Figure 7
— Power OK (P/OK)
Figure 8
— Enable / Output (E/O)
AC
Mains
120 V
RMS
270 Vdc
250 Vdc
DC
Output
of HAM
Boost Voltage
280
Vdc
Rectified Line
Module
Enable
Off at
250 Vdc
25 ms
Power OK
Off at
270 Vdc
Outputs
DC-DC
Converter(s)
10 ms
Off at
375 Vdc
Figure 9
— Start up / shut down timing diagram
Vicor Corp.
Tel: 800-735-6200, 978-470-2900 Fax: 978-475-6715
HAM, Harmonic Attenuation Module
Rev. 1.5
Page 7 of 8
Set your site on VICOR at www.vicorpower.com
VICOR [ VICOR CORPORATION ]
