Pin Description
Pin number Pin name
1
FC
2
OSC
3
COM
4
IRF
5
CI
LB1978V
Equivalent circuit
Vcc
1
PGND
Vcc
2
SGND
Vcc
PGND
Vcc
3
10kΩ
120µA
4
SGND
Vcc
25µA
5
SGND
Pin function
Oscillator and ripple suppression pin.
The higher the capacitance connected to
FG, the more effectively will ripple
components be suppressed.
Startup pulse cycle and drive switching
cycle setting pin.
Increased capacitance will result in higher
startup pulse cycle and drive switching
cycle.
Startup waveform detector offset setting
pin.
RCOM = 1 kΩ results in approx. 25 mV
offset at startup
Oscillator circuit and F-V servo circuit
internal current setting pin.
Speed adjustment pin using CR
oscillation based on FG pulse edge
detection.
Continued on next page
No. 6186-5/9