Equivalent Circuit Block Diagram
OSC
LB1978V
Vcc
DR TC2
TC1 P1P2P3 BR1
Brake
circuit
Divider
Oscillator
Rotation
detector
IRF
COM
S/S
Vref
Constant
current circuit
Current bias
Startup
detection
Startup
switching
Soft switching
Reference
voltage
Speed
select
divider
d/dt
Pulse
Current
buffer
Comparator
VI
SGND
Sample Application Circuit
F/S
CI
PW PV IV
VI
BR2
U1
V1
W1
U2
V2
W2
PGND
DU
FC
0.01
µF
0.01
µF
0.01
µF
100Ω
1µF
30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
Vcc VREF S/S DR F/S W1 V1 U1 PGND W2 V2 U2 DU SGND P3
LB1978V
FC OSC COM IRF CI PW PV IV VI BR1 BR2 TC1 TC2 P1 P2
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
2.2µF
1500pF
1kΩ
180
kΩ
0.1µF
0.01µF
180
kΩ
6.2kΩ
680kΩ
0.1µF
0.33µF
68kΩ 20kΩ
0.033µF
No. 6186-4/9