DS8817A 반도체 회로 부품 판매점
Dual-Phase PWM Controller
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 Richtek |
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RT8817A
Dual-Phase PWM Controller with PWM-VID Reference
General Description
The RT8817A 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-24L 4x4 package.
The RT8817A adopts RDS(ON) current sensing technique.
Current limit is accomplished through continuous inductor-
current-sense, while RDS(ON) current sensing is used for
accurate channel current balance. Using the method of
current sampling utilizes the best advantages of each
technique.
The RT8817A 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, internal soft-start, power good indicator, and
enable functions.
Ordering Information
RT8817A
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 :
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.
Marking Information
3Y= : Product Code
3Y=YM
DNN
YMDNN : Date Code
Copyright ©2016 Richtek Technology Corporation. All rights reserved.
DS8817A-00 September 2016
Features
Dual-Phase PWM Controller
Power State Indicator
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 RDS(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)
Applications
CPU/GPU Core Power Supply
Desktop PC Memory, VTT Power
Chipset/RAM Power Supply
Generic DC-DC Power Regulator
Pin Configuration
(TOP VIEW)
24 23 22 21 20 19
BOOT1 1
18 BOOT2
UGATE1 2
17 UGATE2
EN 3
PSI 4
GND
16 PGOOD
15 NC
VID 5
25 14 NC
REFADJ 6
13 NC
7 8 9 10 11 12
WQFN-24L 4x4
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1
RT8817A
Functional Pin Description
Pin No.
1
Pin Name
Pin Function
BOOT1
Bootstrap supply for PWM 1. This pin powers the high-side MOSFET driver.
2
UGATE1
High-side gate driver of PWM 1. This pin provides the gate drive for the converter's
high-side MOSFET. Connect this pin to the Gate of high-side MOSFET.
3 EN
Enable control input. Active high input. When PVCC POR, the input voltage must
not be over PVCC.
4 PSI
Power saving interface. When the voltage is pulled below 0.4V, the device will
operate into 1 phase DEM. When the voltage is between 0.7V to 0.88V, the device
will operate into 1 phase force CCM. When the voltage is between 1.08V to 1.35V,
the device will operate into 2 phase DEM. When the voltage is between 1.6V to
5.5V, the device will operate into 2 phase force CCM.
5 VID
Programming output voltage control input. Refer to PWM-VID Dynamic Voltage
Control.
6
REFADJ
Reference adjustment output. Refer to PWM-VID Dynamic Voltage Control.
7
REFIN
External reference input.
8
VREF
Reference voltage output. This is a high precision voltage reference (2V) from the
VREF pin to RGND pin.
9 TON
On-time/switching frequency adjustment input. Connect a 100pF ceramic
capacitor between CTON and ground is optional for noise immunity enhancement.
10 RGND Negative remote sense Input. Connect this pin to the ground of output load.
11 VSNS
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
12 OCSET/SS limit threshold. The external soft start time also can be set through by connecting a
capacitor from OCSET/SS pin to GND.
13, 14, 15, 22 NC
No internal connection.
16 PGOOD
17 UGATE2
18 BOOT2
19 PHASE2
20 LGATE2
21 PVCC
23 LGATE1
24 PHASE1
25
(Exposed Pad)
GND
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.
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.
Copyright ©2016 Richtek Technology Corporation. All rights reserved.
www.richtek.com
2
is a registered trademark of Richtek Technology Corporation.
DS8817A-00 September 2016
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DS8817A controller
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