a4930 Allegro MicroSystems, Inc., a4930 Datasheet - Page 6

• Manufacturer Part Number: a4930
• Description: A4930 Single Phase Fan Pre-driver
• Manufacturer: Allegro MicroSystems, Inc.

A4930
SIN
to the fan winding. For temperature-based systems, connect SIN
to a thermistor output. For systems with direct input to the PWM
pin, the pin should be decoupled with a 0.1 μF capacitor. If vari-
able fan speed is not required, for 100% duty cycle, connect this
pin to GND. The input impedance is 200 kΩ (referenced to a
3.5 or 1.5 V rail).
SMIN
duty cycle to the fan winding. The PWM comparator chooses
either SIN or SMIN to determine the output duty cycle, which-
An analog voltage input to this pin sets the duty cycle applied
An analog voltage input to this pin sets the minimum speed
LD
FG
HP
HN
SA
SB
0
V
CDEL
t
CDEL
(1)
V
th
(1)
V
CDEL
(2)
V
th
ever is set to a lower voltage. For 100% duty cycle applications,
connect this pin to GND.
CDEL
the level at which the A4930 switches to slow decay mode in
advance of the Hall zero crossing as shown here:
The resistor should be 25 to 100 kΩ. If this feature is not used,
the CDEL pin should be pulled up to V
(2)
A resistor connected between this pin and GND sets
Single Phase Fan Pre-Driver
V
CDEL
V
V
V
= (2950 / R
th
th
HYS
(1) = V
(2) = V
= V
th
HP
HN
(1) + V
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
CDEL
– V
– V
HN
HP
) – 7 mV
th
(2) = 20 mV (Typical)
= 10 mV (Typical)
= 10 mV (Typical)
REG5
.
with a 5 kΩ resistor.
(mV)
(6)
6