Diodes AH5795 User Manual
Ah5795
AH5795
SINGLE PHASE HALL EFFECT LATCH SMART
FAN MOTOR CONTROLLER
AH5795
Document number: DS35277 Rev. 1 - 2
1 of 13
August 2011
© Diodes Incorporated
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Description
The AH5795 is a single chip solution for driving single-coil
brushless direct current (BLDC) fans and motors. The
integrated full-bridge driver output stage uses soft switching
to minimize audible switching noise and electromagnetic
interference (EMI) providing a low noise solution.
Motor speed can be controlled by either changing the duty
ratio of the PWM signal at the PWM pin or by varying the
supply voltage at Vdd pin.
To help protect the motor coil, the AH5795 provides Rotor
Lock Protection which shuts down the output drive if rotor
lock is detected. The device automatically re-starts when the
rotor lock is removed. Over temperature shutdown provides
thermal protection for the device.
A Tachometer output is provided by open-drain Frequency
Generator (FG) Pin which allows external interface to monitor
motor rotation or speed. The FG output is the magnetic
change frequency.
The AH5795 is available in space saving and low profile
TSOT23-6 and DFN2020C-6 packages.
Features
• Supports single-coil full-wave BLDC fan drivers
• Built-in Hall sensor and input amplifier
• Operating voltage: 1.8V to 6V
• Speed control methods
o
Vdd voltage speed control (PWM pin tied to Vdd)
o
PWM signal speed control via PWM pin
• Soft switching for low noise DC fan motor applications
• Rotor Lock Protection (Lock detection, output shutdown
and automatic re-start)
• Toff clear when PWM is low for greater than 65ms
• Thermal
protection
• Tachometer (FG) output
• No external timing capacitor - Reduces the numbers of
external components required
• Low profile package: TSOT23-6 and DFN2020C-6
• “Green” Molding Compound (No Br, Sb) (Note 1)
Pin Assignments
6
2
4
3
1
(Top View)
O2
Vss
FG
PWM
O1
TSOT23-6
5
Vdd
PWM
Vdd
O1
1
2
3
6
5
4
FG
O2
Vss
(Top View)
DFN2020C-6
Applications
• 3.3V / 5V BLDC Cooling Fans
• Netbook/ Notebook BLDC fans
• Instruments cooling fans
• Low Voltage/ Low Power BLDC Motors
Notes: 1. EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied. Please visit our website at