Driver IC. RT8725 Datasheet

RT8725 IC. Datasheet pdf. Equivalent

RT8725 Datasheet
Recommendation RT8725 Datasheet
Part RT8725
Description Single-Phase BLDC Fan Driver IC
Feature RT8725; ® RT8725 Single-Phase BLDC Fan Driver IC General Description The RT8725 is a single-phase driver I.
Manufacture Richtek
Datasheet
Download RT8725 Datasheet




Richtek RT8725
®
RT8725
Single-Phase BLDC Fan Driver IC
General Description
The RT8725 is a single-phase driver IC for fan motors.
Rotation speed is controlled by PWM input signal. The
RT8725 provides several protection features including
standby mode, thermal shutdown, lock protection, over-
current protection and under-voltage protection. The Built-
in smart force start-up function overcomes and avoids
wrong status when electrical noise occurs during start-
up. In the standby and thermal shutdown mode, the supply
current is less than 100μA. The rotation frequency is
generated by FG output.
Ordering Information
RT8725
Package Type
QU : UDFN-8L 2x3 (U-Type)
Note :
Lead Plating System
G : Green (Halogen Free and Pb Free)
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.
Features
z Low Supply Current
z Smart Force Start-up Function
z PWM Supply Voltage Control Fan Speed
z Built-in Motor Lock Protection and Automatic
Restart
z Built-in Thermal Shutdown
z Built-in Over-Current Protection
z Built-in Frequency Generator with FG Output Signal
z RoHS Compliant and Halogen Free
Applications
z Single Phase Fan Motor for Notebook or PC
Pin Configurations
(TOP VIEW)
OUT2
VCC
H+
H-
1
2
3
4
8 GND
7 OUT1
6 PWM
9 5 FG
UDFN-8L 2x3
Marking Information
0A : Product Code
0AW
W : Date Code
Simplified Application Circuit
Optional
Supply D1
Voltage
D2
Hall
RT8725
VCC OUT2
C1
H+
H- OUT1
FG
Single-Phase
Brushless M
DC Motor
RFG
Pull-High Voltage
PWM Control Signal
PWM
GND
Copyright ©2013 Richtek Technology Corporation. All rights reserved.
DS8725-02 October 2013
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1



Richtek RT8725
RT8725
Function Pin Description
Pin No.
Pin Name
Pin Function
1
OUT2
H-Bridge Output for DC Motor.
2 VCC Supply Voltage Input.
3 H+
Positive Hall Input.
4 H
Negative Hall Input.
5 FG
Frequency Generator Output for Rotation Speed. This is an open-drain
output.
6
PWM
PWM Signal Input.
7 OUT1
8, 9 (Exposed Pad) GND
H-Bridge Output for DC Motor.
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
+
-
OUT1
PWM
GND
FG
Copyright ©2013 Richtek Technology Corporation. All rights reserved.
www.richtek.com
2
is a registered trademark of Richtek Technology Corporation.
DS8725-02 October 2013



Richtek RT8725
RT8725
Operation
Operation Mode
The operation mode of the RT8725 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 RT8725 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 ©2013 Richtek Technology Corporation. All rights reserved.
DS8725-02 October 2013
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
3







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