HV301/HV311
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).
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
8
V
DD
1
PWRGD / PWRGD
R1
487kΩ
ENABLE / ENABLE
Cload
3
2
+5V
UV
R2
6.81kΩ
HV311
DC/DC
PWM
CONVERTER
COM
OV
R3
9.76kΩ
RAMP
V
4
SENSE GATE
EE
7
5
6
C1
10nF
-48V
R4
60mΩ
Q1
IRF530
Note: capacitor may be needed to slow PWRGD dv/dt if
oscillations are observed when VIN is close to OV.
Application Circuit 4
8
GND
V
DD
PWRGD / PWRGD
1
R1
487kΩ
ENABLE / ENABLE
Cload
3
2
+5V
UV
R2
6.81kΩ
HV301/
HV311
DC/DC
PWM
CONVERTER
COM
OV
R3
9.76kΩ
RAMP
V
4
SENSE GATE
EE
7
5
6
C2
C1
10nF
-48V
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.
Application Circuit 5
12
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