SINGLE PHASE HALL EFFECT LATCH SMART
FAN MOTOR CONTROLLER
• Support single-phase full wave DC fan driver
• Built-in Hall sensor input amplifier
• Low voltage startup ( Vdd=1.8V )
• Lock detection and automatic self-restart
• Soft switching for low noise DC fans
• Without external timing capacitor, Reduces the
numbers of external component required
• Thermal protection
• FG output
• Low profile package: SOT89-5L
• SOT89-5L: Available in “Green” Molding Compound
(No Br, Sb)
• Lead Free Finish/ RoHS Compliant (Note 1)
The AH5798 is a single chip solution for driving single-coil
brush-less DC fans and motors. The AH5798 employs a
bidirectional full bridge driver output stage for single coil fan
motor applications. The soft switching driver generates the low
noise operating for DC fans. 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 AH5798 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 the magnetic change frequency. The
device is packaged in SOT89-5L for SMT applications in DC fans.
• 3.3V / 5V Min. BLDC Cooling Fans
• Net-Book/ Note-Book DC fans
• Low Voltage/ Low Power BLDC Motors
Typical Application Circuit
* 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 AH5798 has an open-drain tachometer FG output that follows the magnetic change frequency. A pull-up resistor (10Kohm, typically for System
Power = 5V) connected to a supply voltage.
AH5798 Rev. 1
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