®
RT9624B
Single Phase Synchronous Rectified Buck MOSFET Driver
General Description
The RT9624B is a high frequency, synchronous rectified,
single phase MOSFET driver designed for normal MOSFET
driving applications and high performance CPU VR driving
capabilities.
The RT9624B can be supplied from 4.5V to 13.2V. The
applicable power stage VIN range is from 5V to 24V. The
IC also builds in an internal power switch to replace
external bootstrap diode.
The RT9624B can support switching frequency efficiently
up to 500kHz. The IC has both the UGATE and LGATE
driving circuits for synchronous rectified DC/DC converter
applications. The shoot through protection mechanism is
designed to prevent shoot through between high side and
low side power MOSFETs. The RT9624B has tri-state
PWM input with shutdown function, which can force driver
to output low UGATE and LGATE signals.
The RT9624B comes in a small footprint with 8-pin
packages. The choice of package types includes SOP-8,
SOP-8 (Exposed Pad) and WDFN-8L 3x3.
Features
Drive Two N-MOSFETs
Shoot Through Protection
Embedded Bootstrap Diode
Support High Switching Frequency
Fast Output Rising Time
Tri-State PWM Input for Output Shutdown
Small SOP-8, SOP-8 (Exposed Pad) and 8-Lead
WDFN Packages
RoHS Compliant and Halogen Free
Applications
Core Voltage Supplies for Desktop, Motherboard CPU
High Frequency Low Profile DC/DC Converters
High Current Low Voltage DC/DC Converters
Core Voltage Supplies for GFX Card
Simplified Application Circuit
RT9624B
12V
R1
C1
UGATE
PWM
Controller
PWM
GND
PHASE
+
VCC
BOOT
R2
C
BOOT
R3
Q1
V
IN
C5
C6
L1
V
OUT
R5
Q2
C2
R4
LGATE
C3
C4
Copyright
©
2012 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS9624B-04
October 2012
www.richtek.com
1
RT9624B
Ordering Information
RT9624B
Package Type
S : SOP-8
SP : SOP-8 (Exposed Pad-Option1)
QW : WDFN-8L 3x3 (W-Type)
Lead Plating System
Z : ECO (Ecological Element with
Halogen Free and Pb free)
BOOT
BOOT
PWM
NC
VCC
2
3
4
Pin Configurations
(TOP VIEW)
8
7
6
5
UGATE
PHASE
GND
LGATE
SOP-8
8
2
3
4
UGATE
PHASE
GND
LGATE
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.
PWM
NC
VCC
GND
9
7
6
5
SOP-8 (Exposed Pad)
Marking Information
RT9624BZS
RT9624BZS : Product Number
BOOT
PWM
NC
VCC
1
2
3
4
8
7
6
5
9
UGATE
PHASE
GND
LGATE
RT9624B
ZSYMDNN
WDFN-8L 3x3
YMDNN : Date Code
RT9624BZS
RT9624BZSP : Product Number
RT9624B
ZSPYMDNN
YMDNN : Date Code
RT9624BZQW
03 : Product Code
03 YM
DNN
YMDNN : Date Code
Copyright
©
2012 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
2
GND
DS9624B-04
October 2012
RT9624B
Function Pin Description
SOP-8
1
2
3
4
5
6
7
8
Pin No.
SOP-8 (Exposed Pad) /
WDFN-8L 3x3
1
2
3
4
5
6,
9 (Exposed Pad)
7
8
Pin Name
BOOT
PWM
NC
VCC
LGATE
GND
PHASE
UGATE
Pin Function
Bootstrap Supply for High Side Gate Drive.
PWM Signal Input. Connect this pin to the PWM output of the
controller.
No Internal Connection.
Supply Voltage Input.
Low Side Gate Driver Output. Connect this pin to the Gate of
low side power N-MOSFET.
Ground. The exposed pad must be soldered to a large PCB
and connected to GND for maximum power dissipation.
Connect this pin to the Source of the high side N-MOSFET
and the Drain of the low side N-MOSFET.
High Side Gate Drive Output. Connect this pin to the Gate of
high side power N-MOSFET.
Function Block Diagram
VCC
POR
Internal
VDD
Bootstrap
Control
BOOT
Shoot-Through
Protection
UGATE
PWM
Tri-State
Detect
Turn Off
Detection
VCC
Shoot-Through
Protection
PHASE
LGATE
GND
Copyright
©
2012 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS9624B-04
October 2012
www.richtek.com
3
RT9624B
Operation
POR (Power On Reset)
POR block detects the voltage the VCC pin. When the
VCC pin voltage is higher than POR rising threshold, POR
block output is high. POR output is low when VCC is not
higher than POR rising threshold. When the POR block
output is high, UGATE and LGATE can be controlled by
PWM input voltage. If the POR block output is low, both
UGATE and LGATE will be pulled to low.
Tri-State Detect
When both POR block output and EN pin voltages are
high, UGATE and LGATE can be controlled by PWM input.
There are three PWM input modes, which are high, low,
and shutdown state. If PWM input is within the shutdown
window, both UGATE and LGATE output are low. When
PWM input is higher than its rising threshold, UGATE is
high and LGATE is low. When PWM input is lower than
its falling threshold, UGATE is low and LGATE is high.
Bootstrap Control
Bootstrap control block controls the integrated bootstrap
switch. When LGATE is high (low side MOSFET is turned
on), the bootstrap switch is turned on to charge the
bootstrap capacitor connected to BOOT pin. When LGATE
is low (low side MOSFET is turned off), the bootstrap
switch is turned off to disconnect VCC pin and BOOT
pin.
Turn-Off Detection
Turn-off detection block detects whether high side
MOSFET is turned off by monitoring PHASE pin voltage.
To avoid shoot through between high side and low side
MOSFETs, low side MOSFET can be turned on only after
high side MOSFET is effectively turned off.
Shoot-Through Protection
Shoot-through protection block implements the dead time
when both high side and low side MOSFETs are turned
off. With shoot-through protection block, high side and
low side MOSFET are never turned on simultaneously.
Thus, shoot through between high side and low side
MOSFETs is prevented.
Copyright
©
2012 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
4
DS9624B-04
October 2012
RT9624B
Absolute Maximum Ratings
(Note 1)
−0.3V
to 15V
−0.3V
to 15V
−0.3V
to 30V
−10V
to 35V
−0.3V
to (VCC + 0.3V)
Supply Voltage, VCC --------------------------------------------------------------------------------
BOOT to PHASE -------------------------------------------------------------------------------------
PHASE to GND
DC --------------------------------------------------------------------------------------------------------
< 20ns ---------------------------------------------------------------------------------------------------
LGATE to GND
DC --------------------------------------------------------------------------------------------------------
< 20ns ---------------------------------------------------------------------------------------------------
−2V
to (VCC + 0.3V)
UGATE to GND
DC -------------------------------------------------------------------------------------------------------- (V
PHASE
−
0.3V) to (V
BOOT
+ 0.3V)
< 20ns --------------------------------------------------------------------------------------------------- (V
PHASE
−
2V) to (V
BOOT
+ 0.3V)
PWM to GND ------------------------------------------------------------------------------------------
−0.3V
to 7V
Power Dissipation, P
D
@ T
A
= 25°C
SOP-8 --------------------------------------------------------------------------------------------------- 0.833W
SOP-8 (Exposed Pad) ------------------------------------------------------------------------------ 1.333W
WDFN-8L 3x3 ----------------------------------------------------------------------------------------- 1.429W
Package Thermal Resistance (Note 2)
SOP-8,
θ
JA
--------------------------------------------------------------------------------------------- 120°C/W
SOP-8 (Exposed Pad),
θ
JA
------------------------------------------------------------------------- 75°C/W
SOP-8 (Exposed Pad),
θ
JC
------------------------------------------------------------------------ 15°C/W
WDFN-8L 3x3,
θ
JA
------------------------------------------------------------------------------------ 70°C/W
WDFN-8L 3x3,
θ
JC
------------------------------------------------------------------------------------ 8.2°C/W
Lead Temperature (Soldering, 10 sec.) ---------------------------------------------------------- 260°C
Junction Temperature -------------------------------------------------------------------------------- 150°C
Storage Temperature Range -----------------------------------------------------------------------
−65°C
to 150°C
ESD Susceptibility (Note 3)
HBM (Human Body Model) ------------------------------------------------------------------------- 2kV
Recommended Operating Conditions
(Note 4)
Supply Voltage, VCC -------------------------------------------------------------------------------- 4.5V to 13.2V
Junction Temperature Range -----------------------------------------------------------------------
−40°C
to 125°C
Ambient Temperature Range -----------------------------------------------------------------------
−40°C
to 85°C
Copyright
©
2012 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS9624B-04
October 2012
www.richtek.com
5
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