®
RT8813D
Multi-Phase PWM Controller with PWM-VID Reference
General Description
The RT8813D is a 3/2/1 phase synchronous Buck PWM
controller which is optimized for high performance graphic
microprocessor and computer applications. The IC
integrates a Constant-On-Time (COT) PWM controller, two
MOSFET drivers with internal bootstrap diodes, as well
as channel current balance and protection functions
including Over Voltage Protection (OVP), Under Voltage
Protection (UVP), current limit, and thermal shutdown into
the WQFN-24L 4x4 package.
The RT8813D adopts R
DS(ON)
current sensing technique.
Current limit is accomplished through continuous inductor-
current-sense, while R
DS(ON)
current sensing is used for
accurate channel current balance. Using the method of
current sampling utilizes the best advantages of each
technique.
The RT8813D features external reference input and PWM-
VID dynamic output voltage control, in which the feedback
voltage is regulated and tracks external input reference
voltage. Other features include adjustable switching
frequency, dynamic phase number control, internal soft-
start, power good indicator, and enable functions.
Features
Multi-Phase PWM Controller
Two Embedded MOSFET Drivers and Embedded
Switching Boot Diode
External Reference Input Control
PWM-VID Dynamic Voltage Control
Dynamic Phase Number Control
Lossless R
DS(ON)
Current Sensing for Current Balance
Adjustable Current Limit Threshold
Adjustable Switching Frequency
UVP/OVP Protection
Shoot Through Protection and Short Pulse Free
Technology
Support an Ultra-Low Output Voltage as Standby
Voltage
Thermal Alert Indicator in 2/1 Active Phase
Application
Thermal Shutdown
Power Good Indicator
RoHS Compliant and Halogen Free
Applications
Ordering Information
RT8813D
Package Type
QW : WQFN-24L 4x4 (W-Type)
(Exposed Pad-Option 1)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Note :
Richtek products are :
½
CPU/GPU Core Power Supply
Notebook PC Memory Power Supply
Chipset/RAM Power Supply
Generic DC-DC Power Regulator
Pin Configuration
(TOP VIEW)
PHASE1
LGATE1
PWM3
PVCC
LGATE2
PHASE2
24 23 22 21 20 19
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.
½
Marking Information
4E= : Product Code
BOOT1
UGATE1
EN
PSI
VID
REFADJ
1
2
3
4
5
6
7
8
9 10 11 12
18
17
16
15
25
14
13
GND
BOOT2
UGATE2
PGOOD
VCC/ISEN1
TALERT/ISEN2
TSNS/ISEN3
4E=YM
DNN
YMDNN : Date Code
Copyright
©
2018 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS8813D-03 April 2018
REFIN
VREF
TON
RGND
VSNS
ILIM
WQFN-24L 4x4
www.richtek.com
1
RT8813D
Functional Pin Description
Pin No.
1
2
3
4
Pin Name
Pin Function
BOOT1
Bootstrap supply for PWM 1. This pin powers the high side MOSFET driver.
High side gate driver of PWM 1. This pin provides the gate drive for the converter's
UGATE1
high side MOSFET. Connect this pin to the Gate of high side MOSFET.
EN
Enable control input. Active high input.
Power saving interface. When the voltage is pulled below 0.4V, the device operates
into 1 phase DEM. When the voltage is between 0.8V to 1V, the device operates into
PSI
1 phase forced CCM. When the voltage is between 1.4V to 5.5V, the device
operates into active phase forced CCM (only for 2 or 3 phase).
Programming output voltage control input. Refer to PWM-VID Dynamic Voltage
VID
Control.
REFADJ
Reference adjustment output. Refer to PWM-VID dynamic voltage control.
REFIN
External reference input.
VREF
TON
RGND
VSNS
ILIM
TSNS
ISEN3
TALERT
ISEN2
VCC
ISEN1
PGOOD
UGATE2
BOOT2
PHASE2
LGATE2
PVCC
PWM3
LGATE1
PHASE1
Reference voltage output. This is a high precision voltage reference (2V) from VREF
pin to RGND pin. A 0.1F capacitor should be used to RGND.
On-time/switching frequency adjustment input. Connecting a 100pF capacitor
between C
TON
and ground is optional for noise immunity enhancement.
Negative remote sense input. Connect this pin to the ground of output load.
Positive remote sense input. Connect this pin to the positive terminal of output load.
Current limit setting. Connect a resistor from ILIM pin to GND to set the current limit
threshold.
Temperature sensing input for 2/1 phase operation.
Phase 3 current sense input for 3 phase operation.
Thermal alert. Active low open drain output for 2/1 Phase Operation.
Phase 2 current sense input for 3 phase operation.
Supply voltage input for 2/1 phase operation. (Connect to PVCC)
Phase 1 current sense input for 3 phase operation. (Connect to PHASE1)
Power good indicator output. Active high open drain output.
High side gate driver of PWM 2. This pin provides the gate drive for the converter's
high side MOSFET. Connect this pin to the Gate of high side MOSFET.
Bootstrap supply for PWM 2. This pin powers the high side MOSFET driver.
Switch node for PWM2. This pin is return node of the high side driver of PWM 2.
Connect this pin to the Source of high side MOSFET together with the Drain of low
side MOSFET and the inductor.
Low side gate driver of PWM 2. This pin provides the gate drive for the converter's
low side MOSFET. Connect this pin to the Gate of low side MOSFET.
Supply voltage input. Connect this pin to a 5V bias supply. Place a high quality
bypass capacitor from this pin to GND.
Third phase PWM control signal output to driver for 3 phase operation. In 2/1 Phase
Operation, this pin is high impedance.
Low side gate driver of PWM 1. This pin provides the gate drive for the converter's
low side MOSFET. Connect this pin to the Gate of low side MOSFET.
Switch node for PWM1. This pin is return node of the high side driver of PWM 1.
Connect this pin to the Source of high side MOSFET together with the Drain of low
side MOSFET and the inductor.
Ground. The Exposed pad should be soldered to a large PCB and connected to
GND for maximum thermal dissipation.
is a registered trademark of Richtek Technology Corporation.
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
GND
(Exposed Pad)
www.richtek.com
2
Copyright
©
2018 Richtek Technology Corporation. All rights reserved.
DS8813D-03 April 2018
RT8813D
Functional Block Diagram
VREF
Reference
Output Gen.
PVCC
Mode Select
OV Threshold
Select
UV
40% REFIN
+
-
PWM
CMP
+
-
-
+
Control & Protection Logic
Boot-Phase
Detection 1
Boot-Phase
Detection 2
TON
Gen 1
PWM1
TON
Gen 2
&
TON
Gen 3
Driver
Logic
BOOT1
UGATE1
PHASE1
LGATE1
BOOT2
UGATE2
PHASE2
LGATE2
PWM3
S/H
+
1V
-
Internal
OTP
Current
Balance
S/H
S/H
To Central Logic To Protection Logic
PHASE1
ZCD
To Driver Logic
Current
Limit
-
GM
+
-
GM
+
-
GM
+
V
B
V
B
ISEN3
V
B
Power On Reset
& Central Logic
PGOOD
VID
REFADJ
PSI
REFIN
Soft-Start
& Slew Rate
Control
VSNS
RGND
EN
Enable
Logic
To Driver Logic
To Power On Reset
To Power On Reset
TON
VCC/
ISEN1
TALERT/
ISEN2
TSNS/
ISEN3
V
IN
Detection
Phase
Select
PWM2
I
OCSET
10µ
ILIM
Copyright
©
2018 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS8813D-03 April 2018
www.richtek.com
3
RT8813D
Operation
The RT8813D is a 3/2/1 phase synchronous Buck PWM
controller with integrated drivers which are optimized for
high performance graphic microprocessor and computer
applications. The IC integrates a COT (Constant-On-Time)
PWM controller with two MOSFET drivers, as well as
output current monitoring and protection functions.
Referring to the function block diagram of TON Genx, the
synchronous UGATE driver is turned on at the beginning
of each cycle. After the internal one-shot timer expires,
the UGATE driver is turned off. The pulse width of this
one-shot is determined by the converter's input voltage
and the output voltage to keep the frequency fairly constant
over the input voltage range and output voltage. Another
one-shot sets a minimum off-time.
The RT8813D also features a PWM-VID dynamic voltage
control circuit driven by the pulse width modulation
method. This circuit reduces the device pin count and
enables a wide dynamic voltage range.
Soft-Start (SS)
For internal soft-start function, an internal current source
charges an internal capacitor to build the soft-start ramp
voltage. The output voltage will track the internal ramp
voltage during soft-start interval.
PGOOD
The power good output is an open drain architecture.
When the soft-start is finished, the PGOOD open drain
output is high impedance.
Current Balance
The RT8813D implements internal current balance
mechanism in the current loop. The RT8813D senses per
phase current and compares it with the average current. If
the sensed current of any particular phase is higher than
average current, the on-time of this phase is adjusted to
be shorter.
Current Limit
The current limit circuit employs a unique
“valley”
current
sensing algorithm. If the magnitude of the current sense
signal at PHASE is above the current limit threshold, the
PWM is not allowed to initiate a new cycle. Thus, the
current to the load exceeds the average output inductor
current, the output voltage falls and eventually crosses
the under voltage protection threshold, inducing IC
shutdown.
Over Voltage Protection (OVP) & Under Voltage
Protection (UVP)
The output voltage is continuously monitored for over
voltage and under voltage protection. When the output
voltage exceeds its set voltage threshold (If V
REFIN
≤
1.33V,
OV = 2V, or V
REFIN
> 1.33V, OV = 1.5 x V
REFIN
), UGATE
goes low and LGATE is forced high; when it is less than
40% of its set voltage, under voltage protection is triggered
and then both UGATE and LGATE gate drivers are forced
low. The controller is latched until PVCC is re-supplied
and exceeds the POR rising threshold voltage or EN is
reset.
Copyright
©
2018 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
4
DS8813D-03 April 2018
RT8813D
Absolute Maximum Ratings
(Note 1)
−0.3V
to 30V
−0.7V
to 0.7V
−0.3V
to 6V
−0.3V
to 36V
−5V
to 42V
TON to GND ------------------------------------------------------------------------------------------------------------------
RGND to GND ---------------------------------------------------------------------------------------------------------------
BOOTx to PHASEx --------------------------------------------------------------------------------------------------------
BOOTx to GND
DC ------------------------------------------------------------------------------------------------------------------------------
<100ns ------------------------------------------------------------------------------------------------------------------------
PHASEx to GND (Note 6)
DC ------------------------------------------------------------------------------------------------------------------------------
−0.3V
to 30V
<100ns ------------------------------------------------------------------------------------------------------------------------
−8V
to 36V
UGATEx to PHASEx
DC ------------------------------------------------------------------------------------------------------------------------------
−0.3V
to 6V
<100ns ------------------------------------------------------------------------------------------------------------------------
−5V
to 7.5V
LGATEx to GND
DC ------------------------------------------------------------------------------------------------------------------------------
−0.3V
to 6V
<100ns ------------------------------------------------------------------------------------------------------------------------
−2.5V
to 7.5V
Other Pins --------------------------------------------------------------------------------------------------------------------
−0.3V
to 6V
Power Dissipation, P
D
@ T
A
= 25°C
WQFN-24L 4x4 -------------------------------------------------------------------------------------------------------------
Package Thermal Resistance (Note 2)
WQFN-24L 4x4,
θ
JA
--------------------------------------------------------------------------------------------------------
WQFN-24L 4x4,
θ
JC
-------------------------------------------------------------------------------------------------------
Lead Temperature (Soldering, 10 sec.) --------------------------------------------------------------------------------
Junction Temperature ------------------------------------------------------------------------------------------------------
Storage Temperature Range ---------------------------------------------------------------------------------------------
ESD Susceptibility (Note 3)
HBM (Human Body Model) -----------------------------------------------------------------------------------------------
(Note 4)
3.57W
28°C/W
7°C/W
260°C
150°C
−65°C
to 150°C
2kV
Recommended Operating Conditions
Input Voltage, V
IN
-----------------------------------------------------------------------------------------------------------
Supply Voltage, V
PVCC
----------------------------------------------------------------------------------------------------
Junction Temperature Range ---------------------------------------------------------------------------------------------
Ambient Temperature Range ---------------------------------------------------------------------------------------------
5.5V to 26V
4.5V to 5.5V
−40°C
to 125°C
−40°C
to 85°C
Electrical Characteristics
(T
A
= 25°C unless otherwise specified)
Parameter
PWM Controller
PVCC Supply Voltage
PVCC Supply Current
PVCC Shutdown Current
PVCC POR Threshold
POR Hysteresis
Symbol
V
PVCC
I
SUPPLY
I
SHDN
Test Conditions
Min
4.5
Typ
--
1.5
--
4.1
0.3
Max
5.5
2
10
4.4
--
Unit
V
mA
A
V
V
EN = 3.3V, not switching
EN = 0V
--
--
3.8
--
Copyright
©
2018 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS8813D-03 April 2018
www.richtek.com
5
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