HUMMER SERIES
40 OR 70 WATTS
H
OLD
UP
M
ODULE
2. NORMAL OPERATION
3. LOW LINE OPERATION
Normal operation continues with the capacitor charged and the
input line voltage between 18 and 40 VDC. During this time, the
converter will operate from the line voltage through the external
diode. When the external capacitor reaches its final charge of 40
volts, the HUMMER module enters an idle state, consuming only
enough power to keep the capacitor charged. Idle state power for
the module is approximately 1 watt.
Low line operation occurs when the input voltage drops to a range
between 18 and 12 volts. When the voltage reaches 18 VDC, the
HUMMER module’s VCS closes and then operates in a boost
mode. In this mode, the HUMMER module supplies 40 VDC
through VCS to the converter, and at the same time maintains the
charge on the capacitor. The module will operate indefinitely in this
low line region until the input line voltage drops below 12 VDC.
Note: The HUMMER module itself can sustain continuous voltages
of up to 50 VDC and voltage spikes of 80 volts for up to 50
msec, and it will pass these voltages on to the converter through
the external bypass diode. If these ratings exceed the rating of
the converter, care should be taken to control the line voltage to
prevent damage to the converter.
4. POWER FAIL OPERATION
When the input line voltage drops to 12 VDC, the Power Fail flag
is asserted (pulled low) and the HUMMER module’s boost mode is
disabled. At this point, the converter load is powered by the stored
energy in the external capacitor. When the voltage on the external
capacitor falls to 20 VDC, the Capacitor Charged flag is released
(pulled low), indicating that 90% of the usable stored energy has
been depleted. If the connection has been made between the
Capacitor Charged pin and the converter’s Inhibit pin, the
converter will also be inhibited.
Normal Operation will continue indefinitely until the input voltage
drops below 18 VDC.
30 –
— VIN = 22
— VIN = 23
VIN = 19—
VIN = 19—
20 –
10 –
0 –
VIN
— VIN = 14
— VIN = 10
— VIN = 12
— VCAP
VIN
— VCAP
40 –
30 –
20 –
10 –
0 –
VIN
VCS
WITH
DIODE
VCS
CLOSED
VCS
CLOSED
RAMP
DOWN ON
EXT CAP
— VCAP = 40
VCAP = 20—
40 –
30 –
20 –
10 –
0 –
VCAP = 35—
EXT
CAP
OPEN
POWER
FAIL
0 –
CAP
CHARGED
0 –
INITIALIZATION &
CHARGING
NORMAL
LOW
NORMAL
OPERATION
POWER FAIL
OPERATION
OPERATION LINE
OPERATION
FIGURE 5: HUMMER MODULE SIGNAL DIAGRAM
B6-7
CRANE [ Crane Aerospace & Electronics. ]
