RT8127A PWM Controller Datasheet

RT8127A Datasheet, PDF, Equivalent


Part Number

RT8127A

Description

High Efficiency Dual-Channel Output Synchronous Buck PWM Controller

Manufacture

Richtek

Total Page 21 Pages
Datasheet
Download RT8127A Datasheet


RT8127A
®
RT8127A
High Efficiency Dual-Channel Output Synchronous Buck PWM
Controller with Phase Interleaving and Two LDO Regulators
General Description
The RT8127A is a high efficiency Dual-Channel output
synchronous Buck PWM controller with integrated
MOSFET drivers and two LDOs. This part features Green
Voltage Mode (GVMTM) control, which is specifically
designed to improve efficiency at light load condition. At
light load condition, the RT8127A is pin configurable to
automatically operate in diode emulation mode with
constant on-time PFM to reduce switching frequency so
as to improve conversion efficiency. As the load current
increases, the RT8127A leaves the diode emulation mode
and operates in Continuous Conduction Mode (CCM) with
fixed-frequency, 180° out of phase interleaved PWM to
reduce input capacitance. The RT8127A supports 4.5V to
26V input voltage range and has integrated 5V LDO which
supplies the internal gate drivers as well as the controller.
When channel 1 Buck regulator output voltage is higher
than 5V, the supply voltage will be automatically switched
to the Buck regulator output from the integrated 5V LDO.
The RT8127A supports enable/disable function for each
channel and also features external soft-start, adjustable
switching frequency and power good indication. This device
utilizes lossless inductor DCR current sensing for over
current protection. Other protections include over voltage,
under voltage, thermal shutdown and under voltage
lockout.
The RT8127A is available in a WQFN-28L 4x4 small
footprint package.
Features
Green Voltage Mode (GVMTM) Control
High Light Load Efficiency
Audio-Skip Mode (ASM) at Light Load
Pin Configurable CCM/DEM Operation
180° Interleaving PWM in CCM Operation
Support 4.5V to 26V Input Voltage Range
Integrated 5V MOSFET Driver and Bootstrap Circuit
Integrated 5V and 12V LDO
Enable Control for Each Channel
External/Internal Soft-Start
Programmable LGATE PWM Frequency Setting
(LGFS)
Automatic Switchable 5V Regulator
Power Good Indication
VIN Feed-Forward in Control Loop
Lossless DCR Current Sensing
OVP, UVP, OCP, Thermal Shutdown and UVLO
RoHS Compliant and Halogen Free
Applications
Motherboard, Server, Graphic Card
System Power Supplies
Power Module
Marking Information
2P= : Product Code
2P=YM
DNN
YMDNN : Date Code
Simplified Application Circuit
VOUT2
VIN
1.4µH
942µF
VIN RT8127A
UGATE2
PHASE2
LGATE2
UGATE1
PHASE1
LGATE1
CSP2
CSN2
EN1/SS1
EN2/SS2
GND
CSP1
CSN1
12VLDO
VIN
1.4µH
12V/3.3V
VOUT1
942µF
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
DS8127A-01 June 2014
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1

RT8127A
RT8127A
Ordering Information
RT8127A
Package Type
QW : WQFN-28L 4x4 (W-Type)
Note :
Lead Plating System
G : Green (Halogen Free and Pb Free)
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.
Pin Configurations
(TOP VIEW)
28 27 26 25 24 23 22
UGATE2
BOOT2
PHASE2
LGATE2
PGND2
CSP2
CSN2
1
2
3
4
5
6
7
GND
29
21 UGATE1
20 BOOT1
19 PHASE1
18 LGATE1/RT
17 PGND1
16 CSP1
15 CSN1
8 9 10 11 12 13 14
WQFN-28L 4x4
Functional Pin Description
Pin No. Pin Name
Pin Function
1
UGATE2
Channel 2 High Side MOSFET Floating Gate Driver Output. Connect this pin to the
channel 2 high side MOSFET gate.
2
BOOT2
Channel 2 Bootstrap Flying Capacitor Connection Pin. This pin powers channel 2 high side
MOSFET driver. Connect this pin to PHASE2 with a ceramic capacitor.
3
PHASE2
Channel 2 Switching Node Connection Pin. Connect this pin to the joint of high side
MOSFET source and low side MOSFET drain, and the inductor of channel 2.
4
LGATE2
Channel 2 Low Side MOSFET Gate Driver Output. Connect this pin to the gate of channel
2 low side MOSFET.
5
PGND2
Power Ground of Channel 2. This pin is the return ground of channel 2 low side MOSFET
gate driver. Connect this pin to the PCB ground plane layer with vias.
6 CSP2
Positive Current Sense Input for Channel 2.
7 CSN2
Negative Current Sense Input for Channel 2.
8 FB2
Channel 2 Regulator Output Voltage Feedback Pin. This pin is the inverting input node of
the error amplifier.
9 COMP2 Channel 2 Regulator Compensation Pin. This pin is the output of the error amplifier.
Channel 2 Enable Pin. Pull this pin to ground to disable channel 2. This pin is internally
pulled high. Leave this pin unconnected to enable channel 2 with default soft-start time.
10
EN2/SS2
This pin can also be used for external soft-start interval setting. Connect a ceramic
capacitor to this pin to extend soft-start time.
The input voltage at EN2/SS2 pin must be higher than 2.97V to make sure soft-start can be
finished and PGOOD assertion.
11
PGOOD
Power Good Indicator Output. This pin has an open drain structure. Pull this pin high to a
voltage source with a resistor.
Channel 1 Enable Pin. Pull this pin to ground to disable channel 1. This pin is internally
pulled high. Leave this pin unconnected to enable channel 1 with default soft-start time.
12
EN1/SS1
This pin can also be used for external soft-start interval setting. Connect a ceramic
capacitor to this pin to extend soft-start time.
The input voltage at EN1/SS1 pin must be higher than 2.97V to make sure soft-start can be
finished and PGOOD assertion.
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
www.richtek.com
2
is a registered trademark of Richtek Technology Corporation.
DS8127A-01 June 2014


Features ® RT8127A High Efficiency Dual-Channel Output Synchronous Buck PWM Controller with Phase Interleaving and Two LDO Re gulators General Description The RT812 7A is a high efficiency Dual-Channel ou tput synchronous Buck PWM controller wi th integrated MOSFET drivers and two LD Os. This part features Green Voltage Mo de (GVMTM) control, which is specifical ly designed to improve efficiency at li ght load condition. At light load condi tion, the RT8127A is pin configurable t o automatically operate in diode emulat ion mode with constant on-time PFM to r educe switching frequency so as to impr ove conversion efficiency. As the load current increases, the RT8127A leaves t he diode emulation mode and operates in Continuous Conduction Mode (CCM) with fixed-frequency, 180° out of phase int erleaved PWM to reduce input capacitanc e. The RT8127A supports 4.5V to 26V inp ut voltage range and has integrated 5V LDO which supplies the internal gate dr ivers as well as the controller. When channel 1 Buck regulator ou.
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