Application Information, cont’d.
When the details of the load ENABLE circuitry is not known,
using an optocoupler always provides a safe solution
(Application Circuit 4).
HV301/HV311
Filtering Voltage Spikes on Input Supply
In some systems over voltage spikes of very short duration may
exist. For these systems a small capacitor may be added from
the OV pin to the VEE pin to filter the voltage spikes (Application
Circuit 5).
Optocoupler
GND
R1
487kΩ
R2
6.81kΩ
R3
9.76kΩ
-48V
8
VDD
3 UV
2 OV
1
PWRGD / PWRGD
HV311
RAMP VEE SENSE GATE
7
4
5
6
C1
10nF
R4
60mΩ
Q1
IRF530
Note: capacitor may be needed to slow PWRGD dv/dt if
oscillations are observed when VIN is close to OV.
ENABLE / ENABLE +5V
Cload
DC/DC
PWM
COM
CONVERTER
Application Circuit 4
GND
R1
487kΩ
R2
6.81kΩ
R3
9.76kΩ
-48V
8
VDD
3 UV
2 OV
PWRGD / PWRGD
1
HV301/
HV311
ENABLE / ENABLE +5V
Cload
DC/DC
PWM
COM
CONVERTER
RAMP VEE
7
4
SENSE GATE
5
6
C2
C1
10nF
R4
12.5mΩ
Q1
IRF530
Note: capacitor may be needed to slow PWRGD dv/dt if
oscillations are observed when VIN is close to OV.
12
Application Circuit 5