®
RT8816B
Dual-Phase PWM Controller with PWM-VID Reference
General Description
The RT8816B is a 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-20L 3x3 package.
The RT8816B 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 RT8816B 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
Dual-Phase PWM Controller
Power State Indicator
½
1P-CCM/2P-CCM/1P-DEM/2P-DEM
Two Embedded MOSFET Drivers and Embedded
Switching Boot Diode
Support 1.8V PWM-VID Interface
External Reference Input Control
PWM-VID Dynamic Voltage Control
Dynamic Phase Number Control
Lossless R
DS(ON)
Current Sensing for Current Balance
Internal/External Soft-Start
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 Shutdown
Power Good Indicator (EN to PG high = 500μs)
μ
Applications
Ordering Information
RT8816B
Package Type
QW : WQFN-20L 3x3 (W-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Note :
Richtek products are :
½
CPU/GPU Core Power Supply
Desktop PC Memory, VTT Power
Chipset/RAM Power Supply
Generic DC-DC Power Regulator
Pin Configuration
(TOP VIEW)
PHASE1
LGATE1
PVCC
LGATE2
PHASE2
20 19 18 17 16
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.
BOOT1
UGATE1
EN
PSI
VID
1
2
3
4
5
½
15
14
GND
21
6
7
8
9 10
13
12
11
Marking Information
7J= : Product Code
BOOT2
UGATE2
PGOOD
OCSET/SS
VSNS
7J=YM
DNN
YMDNN : Date Code
WQFN-20L 3x3
Copyright
©
2020 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS8816B-02
February 2020
REFADJ
REFIN
VREF
TON
RGND
www.richtek.com
1
RT8816B
Functional Pin Description
Pin No.
1
2
3
Pin Name
BOOT1
UGATE1
EN
Pin Function
Bootstrap supply for PWM1. This pin powers the high-side MOSFET driver.
High-side gate driver of PWM1. This pin provides the gate drive for the converter's
high-side MOSFET. Connect this pin to the gate of high-side MOSFET.
Enable control input. Active high input. When PVCC POR, the input voltage must
not be over PVCC.
Power saving interface. When the voltage is pulled below 0.4V, the device
operates into 1 phase DEM. When the voltage is between 0.7V to 0.88V, the
device operates into 1 phase forced CCM. When the voltage is between 1.08V to
1.35V, the device operates into 2 phase DEM. When the voltage is between 1.6V
to 5.5V, the device operates into 2 phase forced CCM.
Programming output voltage control input. Refer to PWM-VID Dynamic Voltage
Control.
Reference adjustment output. Refer to PWM-VID Dynamic Voltage Control.
External reference input.
Reference voltage output. This is a high precision voltage reference (2V) from the
VREF pin to RGND pin.
On-time/switching frequency adjustment input. Connecting a 100pF ceramic
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 OCSET/SS to GND to set the current
limit threshold. The external soft start time also can be set through by connecting a
capacitor from OCSET/SS pin to GND.
Power good indicator output. Active high open-drain output.
High-side gate driver of PWM2. 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 PWM2. 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 PWM2. 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.
Low-side gate driver of PWM1. 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.
4
PSI
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
(Exposed Pad)
VID
REFADJ
REFIN
VREF
TON
RGND
VSNS
OCSET/SS
PGOOD
UGATE2
BOOT2
PHASE2
LGATE2
PVCC
LGATE1
PHASE1
GND
Copyright
©
2020 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
2
DS8816B-02
February 2020
RT8816B
Functional Block Diagram
VREF
Reference
Output Gen.
PVCC
RGND
OV
150% REFIN
or 2V
UV
40% REFIN
+
-
Soft-Start
& Slew Rate
Control
VSNS
Enable
Logic
PWM
CMP
+
-
To Driver Logic
To Power On Reset
TON
Gen 2
Mode Select
-
+
Control & Protection Logic
Boot-Phase
Detection 1
Boot-Phase
Detection 2
TON
Gen 1
PWM1
Driver
Logic
BOOT1
UGATE1
PHASE1
LGATE1
BOOT2
UGATE2
PHASE2
LGATE2
Power On Reset
& Central Logic
PGOOD
VID
REFADJ
PSI
REFIN
EN
PWM2
To Power On Reset
V
IN
Detection
TON
Current
Balance
S/H
-
GM
+
-
GM
+
-
I
CS
40µ
I
CS
10µ
OCSET/SS
To Protection Logic
To SSOK
X(-1/12)
Current
Limit
+
-
+
S/H
V
B
V
B
Copyright
©
2020 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS8816B-02
February 2020
www.richtek.com
3
RT8816B
Operation
The RT8816B is a dual-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 RT8816B 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 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 RT8816B implements internal current balance
mechanism in the current loop. The RT8816B 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 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
©
2020 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
4
DS8816B-02
February 2020
RT8816B
Absolute Maximum Ratings
(Note 1)
−0.3V
to 30V
−0.7V
to 0.7V
−0.3V
to 6V
−5V
to 7.5V
−0.3V
to 36V
TON to GND ------------------------------------------------------------------------------------------------------------------
RGND to GND ---------------------------------------------------------------------------------------------------------------
BOOTx to PHASEx
DC ------------------------------------------------------------------------------------------------------------------------------
<100ns ------------------------------------------------------------------------------------------------------------------------
BOOTx to GND
DC ------------------------------------------------------------------------------------------------------------------------------
<100ns ------------------------------------------------------------------------------------------------------------------------
−5V
to 42V
PHASEx to GND
DC ------------------------------------------------------------------------------------------------------------------------------
−5V
to 30V
<100ns ------------------------------------------------------------------------------------------------------------------------
−10V
to 42V
UGATEx to GND
DC ------------------------------------------------------------------------------------------------------------------------------
−5V
to 36V
<100ns ------------------------------------------------------------------------------------------------------------------------
−10V
to 42V
UGATEx to PHASEx
DC ------------------------------------------------------------------------------------------------------------------------------
−0.3V
to 6V
<100ns ------------------------------------------------------------------------------------------------------------------------
LGATEx to GND
DC ------------------------------------------------------------------------------------------------------------------------------
<100ns ------------------------------------------------------------------------------------------------------------------------
Other Pins --------------------------------------------------------------------------------------------------------------------
Power Dissipation, P
D
@ T
A
= 25°C
WQFN-20L 3x3 -------------------------------------------------------------------------------------------------------------
Package Thermal Resistance (Note 2)
WQFN-20L 3x3,
θ
JA
--------------------------------------------------------------------------------------------------------
WQFN-20L 3x3,
θ
JC
-------------------------------------------------------------------------------------------------------
Lead Temperature (Soldering, 10 sec.) --------------------------------------------------------------------------------
Junction Temperature ------------------------------------------------------------------------------------------------------
Storage Temperature Range ---------------------------------------------------------------------------------------------
ESD Susceptibility (Note 3)
HBM (Human Body Model) -----------------------------------------------------------------------------------------------
−5V
to 7.5V
−0.3V
to 6V
−5V
to 7.5V
−0.3V
to 6.5V
2.67W
30°C/W
7.5°C/W
260°C
150°C
−65°C
to 150°C
2kV
Recommended Operating Conditions
(Note 4)
Input Voltage, VIN ---------------------------------------------------------------------------------------------------------- 2.5V to 26V
Supply Voltage, PVCC ---------------------------------------------------------------------------------------------------- 4.5V to 5.5V
Junction Temperature Range ---------------------------------------------------------------------------------------------
−10°C
to 105°C
Copyright
©
2020 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS8816B-02
February 2020
www.richtek.com
5
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