sm5301a Nippon Precision Circuits Inc, (NPC), sm5301a Datasheet - Page 8

• Manufacturer Part Number: sm5301a
• Description: 3-channel Video Buffer With Built-in Wideband Filters
• Manufacturer: Nippon Precision Circuits Inc, (NPC)

Adjusting the Cutoff Frequency
Constant-voltage control 1
Cutoff frequency control using a reference voltage VR generated by voltage divider formed by R1 and R2.
Constant-voltage control 2
Cutoff frequency control by adjusting the resistance connected to RFC.
PWM control
Cutoff frequency control by smoothing the PWM signal, using R1 and C1, input to VFC.
When VFC = 0.2V V
When VFC = 1.6V V
Note: The resistor connected to RFC can affect the cutoff frequency response, so a high-precision component
should be used. It is recommended to set the RC filter cutoff frequency to < fc/100 of the PWM wave-
form frequency.
V
V
DD
DD
DD
DD
= 3.3V, 6% duty drive
= 5.0V, 4% duty drive
= 3.3V, 48% duty drive
= 5.0V, 32% duty drive
PWM
R1
R2
VR
VR
R1
VFC
VFC
C1
VFC
SM5301AS
RFC
RFC
RFC
SEIKO NPC CORPORATION —8