st1115c Silicon Touch Technology Inc., st1115c Datasheet - Page 9

• Manufacturer Part Number: st1115c
• Description: Speed Control Double Coil Brushless Motor Driver
• Manufacturer: Silicon Touch Technology Inc.

3. Fan speed control by the PWM command ―Refer to Figure 5.
(1) Figure 5 shows the application circuit, where the fan speed is directly controlled by the
(2) For this circuit, the PWM command is active high and its frequency range is 200 Hz ~
PWM command. The BJT Q1 together with resistors R1 and R2 constitutes an inverting
level shifter, which is responsible for translating the voltage level of the PWM command
to the VDD voltage level of the drive IC. In this way, the voltage level of the PWM
command can be very low, say, 2 Volt, for example.
40 KHz. If low acoustic noise is desired, the 20 KHz~40 KHz of the PWM frequency
range is recommended.
SP-ST1115CD-A.005
PWM
點晶科技股份有限公司
SILICON TOUCH TECHNOLOGY INC.
R1
R2
Figure 5. Fan speed control via the PWM command.
VSS
Q1
Hall
IC
VSS
C1
1u
C2
1u
VSS
VSS
Hin
VT
CF
Version
ST1115C
GND
VDD
VSS
：
RD
O1
O2
A.005
R3
75
Analog Power
D1
Z1
VSS
ST1115C/ST1115D
Digital Power
VSS
Z2
Page
R4
10K
：
8
RD