Slide 1

Nnergy for the DC/DCInterpoint recommendsacitors because of theirure operation. An alterminum electrolytic. Topacitors should have aacitance of 330 uF, andired will depend on theciency of the converteritance for a given holdto be held up (in watts)oad (in %)n volts)a converter with a effi40 V capacitor charge:3 = 2790 F75.2HUMMER module toicient converter is 37.5maximum of 40 watts toa sheets for individualline and load for eachthe efficiency rating forected to the convertersas the low line figure inONoperation as shown inthe HUMMER modulespin. This diode suppliesnternal voltage controlelected with a minimumdown rating of 50 V oruivalent).CAUTION: Do not connect the HUMMER modules input return pinto the Cext return. This connection will short the modules currentlimit sense resistor resulting in excessive currents that can alsodamage the DC/DC converter.INHIBIT FUNCTIONThe HUMMER modules inhibit pin disables the internal boostconverter when the Inhibit pin is pulled low. This is accomplished byan external connection to the Vin Return pin or Vout Return pin. Theinhibit open circuit voltage is is 10 V and the short circuit current is15 mA. It is open-collector TTL or CMOS compatible. The pin isdiode-isolated and can be reverse biased to include the input potential. Power Fail and Capacitor Charged flags are operable when theunit is inhibited.FLAG FUNCTIONSPOWER FAIL FLAGThe Power Fail Flag output is implemented by a comparator monitoring the input voltage. (The comparator is also used to inhibitHUMMER modules operation; note however, that the flag is functional when the unit is inhibited.) The input voltage threshold isnominally 14.5 V to indicate that sufficient voltage is present foroperation. The comparator output drives an internal MOSFET bufferwhich connects to the external Power Fail pin. The buffer is of anopen drain configuration and requires an external pull-up resistorand voltage for indication. The maximum recommended pull-upvoltage is 36 V. The maximum short circuit should not exceed 10mA.The buffer is protected by a shunt zener diode connected betweenthe drain and the Cext Return. In normal operation, the input voltageexceeds the 14 V threshold and the output is high (open drain).When the input voltage is below 12 V the output is low, and theMOSFET conducts to the Return.CAPACITOR CHARGED FLAGA Capacitor Charged Flag is implemented by a comparator monitoring the HUMMER modules +Cext terminal. The capacitor voltagethreshold is 36 V, at which point the external capacitor is charged to80% of its maximum value. When the capacitor discharges, the flagresets at 20 VDC indicating that approximately 10% of the chargeremains. The comparator output drives a MOSFET buffer amplifier,and the buffer output connects to the Cap Charged pin. The bufferis of an open drain configuration and requires a pull-up resistor andvoltage for indication. The maximum recommended pull-up voltageis 36 V. The maximum short circuit current should not exceed 10mA. During normal operation, the input is 40 V, exceeding thethreshold, and the output is high (open circuit). When the capacitorvoltage is below 20 V, the output is low, and the MOSFET conductsto the Return. The HUMMER module must be supplied with aminimum of 8 VDC for biasing internal circuits to obtain correctoutput states.HOLD UP MODULE