Am4961a, A product line of diodes incorporated – Diodes AM4961A User Manual
Page 9
AM4961A
Document number: DS36626 Rev. 1 - 2
9 of 17
October 2013
© Diodes Incorporated
AM4961A
A Product Line of
Diodes Incorporated
NE
W
P
R
OD
UC
T
Applications Note
Typical Application Circuit for PWM input signal for speed control with AM4961A is shown below. The speed is primarily controlled by a voltage
on the VPWM pin (either from DC voltage signal or PWM inputs signal converted to DC voltage) or alternatively a PWM signal on COSC pin.
OUT2
OUT1
VCC
GND
VMIN
CT
VPWM
VREF
COSC
HIN-
FG
HB
RD
HIN+
Hall
AM4961A
D1
C1
1
µF or greater
R1
27k
R2
10k
R4
39k
R6 330k
R7
100k
R5
100k
PWM
VCC
L1
R3 7.5k
R8
68k
C2
0.33
µF
C3
100pF
C4
0.47
µF
1 (1)
2 (3)
3 (4)
4 (5)
5 (6)
6 (7)
7 (8)
8 (9)
9 (10)
10 (11)
11 (12)
12 (13)
13 (14)
14 (15)
PGND
(16)
Q1
Typical Application Circuit – External PWM Input Speed Control
Note:
9. C1 is for power stabilization and should be 1uF or higher depending on the motor current and motor design.
Power Supply Stabilization
The recommended operating voltage range for AM4961A is 3.5V to 16V. A decoupling capacitor C1 (which also acts as re-circulating capacitor at
commutation) should be connected close to the V
CC
pin. C1 is for power stabilization and should be 1µF or higher depending on the motor
current and motor design.
Hall Bias and Hall Input for Commutation Signal
The HB pin provides a 1.25V Hall bias voltage to drive Hall element. The output of the Hall elements or the Hall switches connect to Hall input H+
and H- pin as described previously in functional description section. To avoid noise, the connection to the Hall element or switch should be as
short as possible. The Hall input stage (H+ and H- pin) has a hysteresis of 20mV typical. The differential Hall input signal should be
50mV peak
or
higher.
Output PWM Frequency Setting – CSOSC Capacitor
The output PWM frequency is generated by comparing VPWM or VMIN (whichever is lower) to the triangular wave on the COSC pin. See “Speed
Control and Minimum Speed Setting” figure.
The triangular wave is generated at the COSC pin when a capacitor C3 is connected between it and the ground. The triangular wave has high
level of 0.3VCC typical and low level voltage of 0.16V
CC
typical. For 12V nominal supply these two levels are 3.6V and 1.95V typically. The
capacitor C3 of 100pF at COSC pin provides output PWM frequency of 25kHZ typical. The C3 capacitor should be connected close to the COSC
pin.