Diodes AH5795 User Manual

AH5795

SINGLE PHASE HALL EFFECT LATCH SMART

FAN MOTOR CONTROLLER

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

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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.

Pin Assignments

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)

Notes: 1. EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied. Please visit our website at

http://www.diodes.com/products/lead_free.html.

Applications

• 3.3V / 5V BLDC Cooling Fans

• Netbook/ Notebook BLDC fans

• Instruments cooling fans

• Low Voltage/ Low Power BLDC Motors

FG

Vss

O2

1

2

PWM

Vdd

O1

(Top View)

TSOT23-6

(Top View)

1

2

3

DFN2020C-6

6

PWM

5

Vdd

43

O1

6

FG

5

O2

4

Vss

AH5795

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Typical Application Circuit

SYSTEM

POWER

D1

C1

AH5795

SINGLE PHASE HALL EFFECT LATCH SMART

FAN MOTOR CONTROLLER

FG

10Kohm

FG

Dz

Vdd

PWM signal for
speed control

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Pin Descriptions

Pin Name Description

Vdd Power supply pin
VSS Ground pin
O1 Output driving & sinking pin
O2 Output driving & sinking pin

PWM PWM signal input pin for speed control

FG Frequency Generator (Note 2)

Notes: 2. The FG output is the same as the magnetic change frequency.

PWM

Vss

AH5795

O1

O2

AH5795

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Functional Block Diagram (Note 3)

AH5795

SINGLE PHASE HALL EFFECT LATCH SMART

FAN MOTOR CONTROLLER

Vdd

Power

Lock Detect,

Shutdown and

Automatic Re-Start

Frequency

Generator

PWM

Soft

Switching

Control

Full Bridge

Driver

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Hall

Sensor

AMP

Logic
Block

Vss

Notes: 3. The AH5795 has an open-drain tachometer FG output that follows the magnetic change frequency. Typically a pull-up resistor of 10KΩ is
recommended from FG pin to the supply voltage.

FG

O1

O2

AH5795

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SINGLE PHASE HALL EFFECT LATCH SMART

FAN MOTOR CONTROLLER

Absolute Maximum Ratings (T

Symbol Characteristics Values Unit

Vdd Supply voltage 7 V

I

Maximum Output Current (Peak) 1000mA mA

O(PEAK)

PD Power Dissipation

TST Storage Temperature Range -65 ~ 150

ESD HBM Human Body Model (HBM) ESD Protection 4 kV

Notes: 4. 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

5. 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.

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= 25°C, unless otherwise noted, Note 4)

A

TSOT23-6 650
DFN2020C-6 780 (Note 5)

AH5795

mW

o

C

Recommended Operating Conditions (T

= 25°C)

A

Symbol Parameter Conditions Min Max Unit

VDD Supply Voltage Operating 1.8 6.0 V
TA Operating Ambient Temperature Range Operating -40 105 oC

Electrical Characteristics (T

Symbol Characteristics Conditions Min Typ. Max Unit

IDD Supply Current No Load - 2.2 - mA
VOH Output Voltage High

VOL Output Voltage Low

Voh+Vol

TSW Output Switching Slope Duration 17Ω load on out1/out2 - 200 - μs

I

LEAK

V

FGOL

TON On Time 350 500 650 ms

RDR Duty Ratio T

V

PWMH

V

PWML

I

PWMH

I

PWMH

F

PWM

D

PWM_MIN

Tj_

SDN_TH

Tj_

SDN_HYST

Output voltage of N- and PMOS
combined

FG Output Leakage Current - - 5 μA

FG Output Voltage Low I

PWM Input H Level - 0.5 Vdd - Vdd V

PWM Input L Level - 0 - 0.14 Vdd V
PWM Input current H Level PWM=Vdd 0 uA
PWM Input current L Level PWM=GND -10 uA
PWM Input Frequency - 0.02 - 50 KHz

Output minimum duty ratio Motor rotating; 10% 100 %

IC junction temperature thermal
shutdown threshold
IC junction temperature thermal
shutdown hysteresis

= 25°C, V

A

= 5V)

DD

= 300mA 4.70 4.88 - V

I

OUT

I

= 500mA 4.5 4.8 - V

OUT

= 300mA - 0.12 0.3 V

I

OUT

I

= 500mA - 0.2 0.5 V

OUT

I

= 300mA 0.3 0.6 V

OUT

I

= 500mA 0.5 V

OUT

= 5mA - - 0.4 V

FG

/ TON - 10 -

OFF

175

25

o

C

o

C

AH5795

Document number: DS35277 Rev. 1 - 2

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August 2011

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