Diodes AH5794 User Manual
SINGLE PHASE HALL EFFECT LATCH FAN MOTOR DRIVER
Description
The AH5794 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.
Low operating voltage down to 1.8V allows motor speed to be
controlled by varying the supply voltage.
To help protect the motor coil, the AH5794 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
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Generator (FG) Pin which allows external interface to monitor
motor rotation or speed. The FG output is the magnetic
change frequency.
The AH5794 is available in space saving and low profile
TSOT26 and U-DFN2020C-6 packages.
Features
Pin Assignments
1
2
V
SS
3
O2
NC
V
DD
O1
U-DFN2020C-6
Applications
(Top View)
TSOT26
(Top View)
1
2
3
AH5794
6
NCFG
V
5
DD
O1
4
FG
6
O2
5
V
4
SS
• Supports single-coil full-wave BLDC fan drivers
• Built-in Hall sensor and input amplifier
• Operating voltage: 1.8V to 6V
• VDD voltage speed control
• Soft switching for low noise DC fan motor applications
• Rotor Lock Protection (Lock detection, output shutdown
and automatic re-start)
• Thermal protection
• Tachometer (FG) output
• No external timing capacitor - Reduces the numbers of
external components required
• Low profile package: TSOT26 and U-DFN2020C-6
• Halogen and Antimony free “Green” packages.
• Lead Free Finish/ RoHS Compliant
AH5794
Document number: DS35809 Rev. 1 - 2
www.diodes.com
• 3V/ 3.3V/ 5V BLDC Cooling Fans
• Netbook/ Notebook BLDC fans
• Instruments cooling fans
• Low Voltage/ Low Power BLDC Motors
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Typical Application Circuit
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AH5794
SINGLE PHASE HALL EFFECT LATCH FAN MOTOR DRIVER
Pin Descriptions
Pin Name Description
VDD
V
SS
O1 Output driving & sinking pin
O2 Output driving & sinking pin
NC No connection
FG Frequency generator (Note 1)
Notes: 1. The FG output is the same as the magnetic change frequency.
AH5794
Document number: DS35809 Rev. 1 - 2
Power supply pin
Ground pin
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Functional Block Diagram (Note 2)
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AH5794
SINGLE PHASE HALL EFFECT LATCH FAN MOTOR DRIVER
Notes: 2.The AH5794 has an open-drain tachometer FG output that follows the magnetic change frequency. Typically a pull-up resistor of 10k is
recommended from FG pin to the supply voltage.
AH5794
Document number: DS35809 Rev. 1 - 2
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March 2012
© Diodes Incorporated
AH5794
Absolute Maximum Ratings (T
Symbol Characteristics Values Unit
VDD
I
O(PEAK)
PD
TST
ESD HBM Human Body Model ESD Protection 4 kV
Notes: 3. Stresses greater than the 'Absolute Maximum Ratings' specified above, may cause permanent damage to the device. These are stress ratings only;
functional operation of the device at these or any other conditions exceeding those indicated in this specification is not implied. Device reliability
may be affected by exposure to absolute maximum rating conditions for extended periods of time
4. U-DFN2020C-6 exposed pad soldered to minimum recommended landing pads (see Package Outline Dimension section) on a two-layer 2oz.
copper FR4 PCB (1.6mm thickness) with no thermal vias in exposed PADs or any copper flood connecting to the landing pattern of the
exposed pad.
Recommended Operating Conditions (T
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Symbol Parameter Conditions Min Max Unit
VDD Supply Voltage at VDD pin
TA
Electrical Characteristics (T
Symbol Characteristics Conditions Min Typ. Max Unit
IDD
VOH
VOL
VOH +VOL
TSW
I
LEAK
V
FGOL
TON
RDR
TJ_
SDN_TH
TJ_
SDN_HYST
AH5794
Document number: DS35809 Rev. 1 - 2
Supply Voltage 7 V
Maximum Output Current (Peak) 1000 mA
Power Dissipation
Storage Temperature Range -65 ~ +150
Operating Ambient Temperature Range Operating -40 +105
Supply Current No Load - 2.2 - mA
Output Voltage High
Output Voltage Low
Output voltage of N- and PMOS
combined
Output Switching Slope Duration 17 load on O1/O2 - 200 - s
FG Output Leakage Current - - 5 A
FG Output Voltage Low
On Time 350 500 650 ms
Duty Ratio
IC junction temperature thermal
shutdown threshold
IC junction temperature thermal
shutdown hysteresis
SINGLE PHASE HALL EFFECT LATCH FAN MOTOR DRIVER
= 25°C, unless otherwise noted, Note 3)
A
TSOT26 650
U-DFN2020C-6 750 (Note 4)
= 25°C)
A
DC supply speed control mode 1.8 6.0 V
= 25°C, V
A
= 5V)
DD
I
OUT
I
OUT
I
OUT
I
OUT
I
OUT
I
OUT
I
FG
T
OFF
= 300mA
= 500mA
= 300mA
= 500mA
= 300mA
= 500mA
= 5mA
/ TON
4.70 4.88 - V
4.5 4.8 - V
- 0.12 0.3 V
- 0.2 0.5 V
0.3 0.5 V
0.5 V
- - 0.4 V
- 10 -
175
25
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© Diodes Incorporated
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