HUMMER SERIES

40 OR 70 WATTS

®

5

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.

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.

Normal Operation will continue indefinitely until the input voltage

drops below 18 VDC.

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.

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.

INITIALIZATION &

CHARGING

NORMAL

OPERATION

LOW

LINE

OPERATION

NORMAL

OPERATION

POWER FAIL

OPERATION

—

—

VCS

WITH

DIODE

30 –

20 –

10 –

0 –

40 –

30 –

20 –

10 –

0 –

40 –

30 –

20 –

10 –

0 –

0 –

EXT

CAP

CAP

CHARGED

—

—

—

—

VCS

CLOSED

RAMP

DOWN ON

EXT CAP

VCS

CLOSED

—

0 –

POWER

FAIL

OPEN

—