Diodes AH5792 User Manual
AH5792
SINGLE PHASE HALL EFFECT LATCH SMART
FAN MOTOR CONTROLLER
Description
The AH5792 is a single chip solution for driving single-coil
brush-less DC fans and motors. The AH5792 employs a
bidirectional full bridge driver output stage for single coil fan
motor applications. The device includes features such as
Rotor Lock Protection with rotor lock detection and automatic
self-restart to avoid damage to the coil when the rotor is
blocked.
The AH5792 also offers an externally controlled Tachometer
(Frequency Generator Pin) open -drain output which makes it
easier to connect with external interface such as hardware
monitoring. The FG is half (1/2) the magnetic change
frequency.
The devices are packaged in SOT553 and SOT 89-5L small
outline packages for applications such as small motors like
vibration motors or ultra thin cooling fans.
Pin Assignments
( Top View )
1
O2
2
V
SS
O1
O2
1
2
Vss
3 7
O1
SOT553
( Top View )
SOT89-5L
5
FG
NC
43
Vdd
FG
5
NC
4
Vdd
Features
• Support single-phase full wave min fan driver
• Built-in Hall sensor input amplifier
• Low voltage startup ( Vdd=1.8V )
• Lock detection and automatic self-restart
• Without external timing capacitor, Reduces the numbers
of external component required
• FG output
• Low profile package : SOT553 and SOT89-5L
• “Green” Molding Compound
AH5792
Document number: DS314641 Rev. 6 - 2
www.diodes.com
Applications
• 3.3V / 5V Min. DC Fans (Eight Pole)
• Low Voltage / BLDC Motors
• Micro-Vibration Motors
1 of 10
July 2010
© Diodes Incorporated
Typical Application Circuit (Note 1)
SYSTEM
POWER
D1
C1
Dz
AH5792
SINGLE PHASE HALL EFFECT LATCH SMART
FAN MOTOR CONTROLLER
SYSTEM
POWER
10Kohm
V
dd
FG
FG
AH5792
V
SS
Notes: 1. Reverse connection of power supply may break the device. A countermeasure is needed such as using reverse power protection
diode D1 between power supply and Vdd terminal. In such case of using reverse power protection diode D1 because of there is no
way to return current to power supply, please take necessary measures like below.
- Connect Dz (Zener diode) between Vdd and Vss terminal, not to exceed the absolute maximum rating voltage.
- Connect a capacitor C1 between Vdd and Vss terminal, to make the path of return current to power supply.
The AH5792 has an open-drain tachometer FG output that follows the half (1/2) the magnetic change frequency. A pull-up resistor
(10Kohm, typically for System Power = 5V) connected to a supply voltage.
O1
O2
Pin Descriptions (Note 2)
Pin Name Description
O1 Output driving & sinking pin 1
Vdd Power supply pin
Vss Ground pin
FG Frequency Generator (Note 2)
O2 Output driving & sinking Pin 2
NC No Connection
Notes: 2. The FG is half (1/2) the magnetic change frequency.
AH5792
Document number: DS314641 Rev. 6 - 2
2 of 10
www.diodes.com
July 2010
© Diodes Incorporated
Functional Block Diagram
AH5792
SINGLE PHASE HALL EFFECT LATCH SMART
FAN MOTOR CONTROLLER
V
dd
V
SS
Operating (Note 3, 4, 5)
Magentic
S
N
Hall
Sensor
Power
AMP
Frequency
Generator
Logic
Block
Lock
Detector
FG
O1
Full Bridge
Driver
O2
Out 1
Out 2
FG
Normal spinning
motor locked detected
Notes: 3. In “Normal spinning, the FG shall change its state at each rising edge of OUT2. In “Mechanical lock”, the FG state is kept as the
same as the moment of motor locked detected.
4. When magnetic is locked as “S” pole, then out1 is kept on “L”, out2 is a clock with Ton/Toff ratio. When magnetic is locked at
“N” pole, then out 2 is kept on “L”, out 1 is a clock with Ton/Toff ratio.
5. When “Re-start spinning” occurs, the motor shall ramp up to the “Normal Spinning” speed from zero. It depends on the motor
characteristics.
Ton
Toff
Mechanical lock
“Re-start spinning”
motor locked cleared
AH5792
Document number: DS314641 Rev. 6 - 2
3 of 10
www.diodes.com
July 2010
© Diodes Incorporated
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