Motor Driver. RT8720A Datasheet

RT8720A Driver. Datasheet pdf. Equivalent

RT8720A Datasheet
Recommendation RT8720A Datasheet
Part RT8720A
Description Single-Phase Full-Wave Fan Motor Driver
Feature RT8720A; ® RT8720A Single-Phase Full-Wave Fan Motor Driver General Description The RT8720A is a single-phas.
Manufacture Richtek
Datasheet
Download RT8720A Datasheet




Richtek RT8720A
®
RT8720A
Single-Phase Full-Wave Fan Motor Driver
General Description
The RT8720A is a single-phase driver IC for fan motors.
Rotation speed is controlled by supply voltage modulation
and PWM input signal. The RT8720A provides several
protection features including lock protection, thermal
shutdown, over-current protection and under-voltage
protection. In thermal shutdown mode, the supply current
is less than 100μA. The rotation frequency is generated
by FG output.
Ordering Information
RT8720A
Package Type
QU : UDFN-8SL 2x2 (U-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Note :
Richtek products are :
RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
Suitable for use in SnPb or Pb-free soldering processes.
Marking Information
1U : Product Code
1UW
W : Date Code
Features
Low Supply Current
PWM Supply Voltage Control Fan Speed
Supply Voltage Speed Control
Smart Force Start-up Function
Built-in Lock Protection
Built-in Thermal Shutdown
Built-in Over-Current Protection
Built-in Frequency Generator with FG Output Signal
Include Hall Bias Circuit
RoHS Compliant and Halogen Free
Applications
Single-Phase Fan Motor for Notebook or PC
Pin Configurations
(TOP VIEW)
OUT2
H+
HB
H-
1
2
3
4
8 OUT1
7 VCC
6 PWM
9 5 FG
UDFN-8SL 2x2
Simplified Application Circuit
Supply
Voltage
Optional
D1
D2
RT8720A
VCC
OUT2
C1
Pull-High Voltage
PWM Control Signal
RFG
OUT1
FG H+
HB
PWM
H-
GND
Single-Phase
Brushless M
DC Motor
Hall
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
DS8720A-01 February 2014
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1



Richtek RT8720A
RT8720A
Function Pin Description
Pin No.
Pin Name
Pin Function
1
OUT2
Output of H-Bridge for DC Motor.
2 H+
Positive Hall Input.
3 HB
Hall Bias Voltage Output.
4 H
Negative Hall Input.
5 FG
Output for Rotation Speed. This is an open drain output.
6
PWM
PWM Signal Input.
7 VCC Power Supply Input.
8
OUT1
Output of H-Bridge for DC Motor.
9 (Exposed Pad) GND
Power Ground. The Exposed Pad should be soldered to a large PCB and
connected to GND for maximum thermal dissipation.
Function Block Diagram
VCC
H+
H-
+
-
+
-
+
-
OUT2
- VCC
+
Control
+
-
OSC
Lock
Protection
TSD
OCP
Hall
Bias
OUT1
PWM
GND
FG
HB
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
www.richtek.com
2
is a registered trademark of Richtek Technology Corporation.
DS8720A-01 February 2014



Richtek RT8720A
RT8720A
Operation
Operation Mode
The operation mode of the RT8720A is determined by the
external PWM input. During power up, if the PWM input
stays at a low-level voltage, the IC will enter low-power
standby mode. If the PWM input is kept at a high-level
voltage or with a periodic pulse signal, the IC will operate
in normal mode. On the other hand, during normal mode
operation, when the PWM input is set to a low-level voltage
for more than 1ms (typ.), the IC will enter low-power standby
mode. In the standby mode, the supply current can be
reduced to 100μA. Once the PWM input is pulled high
again, the IC will be activated immediately for normal
operation.
PWM
tSD = 1ms
Motor Lock Protection and Automatic Restart
When the motor is locked, the RT8720A will try to re-
start the motor within 0.5 seconds typically (tON). If the
motor fails to re-start, the driver will disable the output
regardless of the PWM duty ratio to prevent the motor
coil from burnout. After the lock off-time of 5 seconds in
typical (tOFF), the driver will try to restart the motor again.
If the motor is still locked, then the iteration of the lock
detection and restart will be repeated until the lock condition
is released or the PWM input is pulled low.
H+
H-
OUT1
Mode Normal Mode Standby Mode Normal Mode
OUT2
FG
ICC
tON tOFF
tON tOFF
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
DS8720A-01 February 2014
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
3







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