®
RT9629A
Triple-Channel Synchronous Rectified Buck MOSFET
Driver
General Description
The RT9629A is a high frequency, triple-channel
synchronous rectified buck MOSFET driver specifically
designed to drive six power N-MOSFETs. The part is
promoted to pair with Richtek's multiphase buck PWM
controller family for high-density power supply
implementation. The output drivers of RT9629A can
efficiently switch power MOSFETs at frequency 300kHz
typically. Operating in higher frequency should consider
the thermal dissipation carefully. The device implements
bootstrapping on the upper gate with only an external
capacitor and a diode required. This reduces circuit
complexity and allows the use of higher performance, cost
effective N-MOSFETs. All drivers incorporate adaptive
shoot-through protection to prevent upper and lower
MOSFETs from conducting simultaneously and shorting
the input supply. The RT9629A has also detected the fault
condition during initial start-up before the multi-phase PWM
controller takes control. As a result, the input supply will
latch into the shutdown state. The RT9629A comes in a
small footprint package with WQFN-24L 5x5 package.
Features
Drive Six N-MOSFETs for 3-Phase Buck PWM Control
Shoot Through Protection
Embedded Bootstrap Diode
Support High Switching Frequency
Fast Output Rising Time
Tri-State PWM Input for Output Shutdown
Enable Control
Small 24-Lead WQFN Package
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
Marking Information
RT9629AZQW : Product Number
RT9629A
ZQW
YMDNN
YMDNN : Date Code
Simplified Application Circuit
12V
VCCx
RT9629A
PWM1
PWM2
PWM3
Chip Enable
PHASE1
PWM1
PWM2
PWM3
EN1
EN2
EN3
PHASE3
GND
L3
PHASE2
L2
L1
V
OUT
V
IN
Copyright
©
2012 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS9629A-03 October 2012
www.richtek.com
1
RT9629A
Ordering Information
RT9629A
PHASE3
Pin Configurations
(TOP VIEW)
BOOT2
20
Lead Plating System
Z : ECO (Ecological Element with
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.
24
23
22
VCC2
GND
Package Type
QW : WQFN-24L 5x5 (W-Type)
LGATE3
21
19
18
17
16
UGATE3
BOOT3
GND
EN3
PWM3
EN2
UGATE2
1
2
3
PHASE2
LGATE2
VCC1
LGATE1
GND
PHASE1
GND
4
5
25
6
7
8
9
10
11
12
13
15
14
PWM2
PWM1
POR
EN1
WQFN-24L 5x5
Function Pin Description
Pin No.
1, 12, 19
Pin Name
UGATE3,
UGATE1,
UGATE2
BOOT3,
BOOT1,
BOOT2
Pin Function
High Side Gate Drive Outputs for Phase 3, Phase 1, and Phase 2. Connect this
pin to the Gate of high side power MOSFET.
Bootstrap Power Pins for Phase 3, Phase 1, and Phase 2. This pin powers the
high side MOSFET driver. Connect this pin to the junction of the bootstrap
capacitor and the cathode of the bootstrap diode.
Ground. The exposed pad must be soldered to a large PCB and connected to
GND for maximum power dissipation.
Chip Enable (Active High). When this pin is low, both UGATEx and LGATEx are
driven to low.
PWM Signal Input. Connect this pin to the PWM output of the controller.
Power On Reset Signal.
Switch Nodes of High Side Driver 1, Driver 2, and Driver 3. Connect this pin to
the high side MOSFET Source together with the low side MOSFET Drain and
the inductor.
Low Side Gate Drive Output for Phase 1, Phase 2, and Phase 3. This pin drives
the Gate of low side MOSFET.
Supply Input Pin. VCC1 supplies current for Channel 1 and Channel 2 gate
drivers. VCC2 supplies current for Channel 3 gate driver.
2, 11, 20
3, 14, 23,
GND
25 (Exposed Pad)
4, 6, 8
EN3,
EN2,
EN1
PWM3,
PWM2,
PWM1
POR
PHASE1,
PHASE2,
PHASE3
LGATE1,
LGATE2,
LGATE3
VCC1, VCC2
5, 7, 9
10
13, 18, 24
15, 17, 22
16, 21
Copyright
©
2012 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
2
DS9629A-03 October 2012
UGATE1
BOOT1
RT9629A
Function Block Diagram
VCC1
VCC2
POR
EN1
Internal
VDD
Enable
Detect
POR
Bootstrap
Control
BOOT1
Shoot-Through
Protection
UGATE1
PWM1
Tri-State
Detect
Turn Off
Detection
VCC1
Shoot-Through
Protection
PHASE1
LGATE1
GND
VCC1
Bootstrap
Control
EN2
Internal
VDD
Enable
Detect
BOOT2
Shoot-Through
Protection
UGATE2
PWM2
Tri-State
Detect
Turn Off
Detection
VCC1
Shoot-Through
Protection
PHASE2
LGATE2
VCC2
Bootstrap
Control
EN3
Internal
VDD
Enable
Detect
GND
BOOT3
Shoot-Through
Protection
UGATE3
PWM3
Tri-State
Detect
Turn Off
Detection
VCC2
Shoot-Through
Protection
PHASE3
LGATE3
GND
Copyright
©
2012 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS9629A-03 October 2012
www.richtek.com
3
RT9629A
Operation
POR (Power On Reset)
POR block detects the voltage at VCC1 pin and VCC2
pin. When the VCC1 and VCC2 pin voltage is higher than
POR rising threshold, POR pin output voltage (POR output)
is high. POR output is low when VCC1 and VCC2 are not
both higher than POR rising threshold. When the POR
pin voltage is high, UGATEx and LGATEx can be controlled
by ENx pin and PWMx pin voltage. With low POR pin
voltage, both UGATEx and LGATEx will be pulled to low.
Turn-Off Detection
Enable Detect
When ENx pin input voltage is higher/lower than EN rising
threshold, MOSFET driver is enabled/disabled. When the
ENx input and POR output are high, UGATEx and LGATEx
can be controlled by PWMx input voltage. When ENx
input is low, both UGATEx and LGATEx are pulled to low.
Shoot-Through Protection
Tri-State Detect
When both POR block output and ENx pin voltages are
high, UGATEx and LGATEx can be controlled by PWMx
input. There are three PWMx input modes, which are high,
low, and shutdown state. If PWMx input is within the
shutdown window, both UGATEx and LGATEx output are
low. When PWMx input is higher than its rising threshold,
UGATEx is high and LGATEx is low. When PWMx input
is lower than its falling threshold, UGATEx is low and
LGATEx is high.
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.
Turn-off detection block detects whether high side
MOSFET is turned off by monitoring PHASEx 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.
Bootstrap Control
Bootstrap control block controls the integrated bootstrap
switch. When LGATEx is high (low side MOSFET is
turned on), the bootstrap switch is turned on to charge
the bootstrap capacitor connected to BOOTx pin. When
LGATEx is low (low side MOSFET is turned off), the
bootstrap switch is turned off to disconnect VCCx pin and
BOOTx pin.
Copyright
©
2012 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
4
DS9629A-03 October 2012
RT9629A
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, VCC1, VCC2 ---------------------------------------------------------------------
BOOTx to PHASEx ----------------------------------------------------------------------------------
PHASEx to GND
DC --------------------------------------------------------------------------------------------------------
< 20ns ---------------------------------------------------------------------------------------------------
LGATEx to GND
DC --------------------------------------------------------------------------------------------------------
< 20ns ---------------------------------------------------------------------------------------------------
−2V
to (VCC + 0.3V)
UGATEx to GND
DC -------------------------------------------------------------------------------------------------------- (V
PHASE
−
0.3V) to (V
BOOT
+ 0.3V)
< 20ns --------------------------------------------------------------------------------------------------- (V
PHASE
−
2V) to (V
BOOT
+ 0.3V)
ENx, PWMx to GND ---------------------------------------------------------------------------------
−0.3V
to 7V
POR to GND -------------------------------------------------------------------------------------------
−0.3V
to 5V
Power Dissipation, P
D
@ T
A
= 25°C
WQFN-24L 5x5 --------------------------------------------------------------------------------------- 2.778W
Package Thermal Resistance (Note 2)
WQFN-24L 5x5,
θ
JA
---------------------------------------------------------------------------------- 36°C/W
WQFN-24L 5x5,
θ
JC
--------------------------------------------------------------------------------- 6°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, VCC1, VCC2 --------------------------------------------------------------------- 4.5V to 13.2V
Junction Temperature Range -----------------------------------------------------------------------
−40°C
to 125°C
Ambient Temperature Range -----------------------------------------------------------------------
−40°C
to 85°C
Electrical Characteristics
(V
CCx
= 12V, T
A
= 25°C unless otherwise specified)
Parameter
Power Supply Voltage
Power Supply Current
Power On Reset (POR)
POR Rising Threshold
POR Falling Threshold
POR Pin High Voltage
POR Pin Low Voltage
Symbol
V
CC
I
VCC
V
POR_r
V
POR_f
V
POR_H
V
POR_L
Test Conditions
Min
4.5
Typ
--
250
Max
13.2
--
Unit
V
μA
V
BOOTx
= 12V, PWMx Floating
V
CCx
Rising
V
CCx
Falling
--
--
3
--
--
4
3.5
3.5
--
4.4
--
4
0.5
V
V
V
V
Copyright
©
2012 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS9629A-03 October 2012
www.richtek.com
5
Embedded System
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