AM4964

Document number: DS37241 Rev. 2 - 2

10 of 21

www.diodes.com

June 2014

© Diodes Incorporated

AM4964

A Product Line of

Diodes Incorporated

RADJ

– Adjust the Line Slope of the Input PWM Duty vs. Output PWM Duty at the OUT1 and OUT2

Adjust Slope K of the fan rotating speed

（or output duty）vs. input duty to approximately match the target specification using R5 and R6.

Output PWM Duty Slope K vs. Input PWM Duty with Slope K R5 and R6

VMIN

– Minimum Speed Setting

A voltage can be set on this pin via a potential divider between the VREF (or Supply) and GND pins. This voltage is monitored by the PWM pin

to clamp the PWM control voltage so that it does not rise above VMIN voltage. As a higher voltage on the PWM pin represents a lower speed,

the VMIN setting prevents the motor speed going lower than the minimum speed set by the VMIN pin. When the VMIN voltage is higher than the

Adjust the minimum speed vs. input duty to approximately match the target specification via R2 (R1=15k

Ω). Measure the fan rotating speed and

the input duty, as shown below.

0

1

2

3

4

5

6

7

8

9

10

0

20

40

60

80

100

Output PWM Duty vs. R2

0

10

20

30

40

50

60

70

80

90

100

0

20

40

60

80

100

R5 is open

Input Duty (%)

0

20

40

60

80

100

0

20

40

60

80

100

R6 open

Input Duty (%)