RT5785A Step-Down Converter Datasheet

RT5785A Datasheet, PDF, Equivalent


Part Number

RT5785A

Description

Synchronous Step-Down Converter

Manufacture

Richtek

Total Page 14 Pages
Datasheet
Download RT5785A Datasheet


RT5785A
®
RT5785A/B
2A, 6V, 1.5MHz, 25μA IQ, ACOTTM Synchronous Step-Down
Converter
General Description
The RT5785A/B is a high-performance, Advanced Constant
On-Time (ACOTTM) monolithic synchronous step-down
DC-DC converter that can deliver up to 2A output current
from a 2.5V to 6V input supply. The proprietary ACOT
control architecture features quick transient response and
provides stable operation with small ceramic output
capacitors and without complicated external
compensation. The switching ripple voltage is easily
smoothed–out by small package filtering elements due
to a constant switching frequency of 1.5MHz and the
maximum duty cycle of 100% allows the device to operate
at low dropout use. With internal low on-resistance power
switches and extremely low quiescent current, the
RT5785A/B displays excellent efficiency and good behavior
across a range of applications.
Cycle-by-cycle current limit provides protection against
shorted outputs, input under-voltage lock-out, output
under-voltage protection, and thermal shutdown provide
safe and smooth operation in all operating conditions. The
RT5785A/B is available in the TSOT-23-8 (FC) package.
Features
Dramatically Fast Transient Response
Steady 1.5MHz ±200kHz Switching Frequency
Very Low Input Quiescent and Shutdown Currents
Advanced COT Control Loop Design
Optimized for Ceramic Output Capacitors
2.5V to 6V Input Voltage Range
Accurate Voltage Reference 0.6V ±2%
Integrated 100mΩ/60mΩ MOSFETs
Internal Start-Up into Pre-Biased Outputs
Power Good Indicator
Enable Control
Over-Current and Over-Temperature Protections
Under-Voltage Protection with Hiccup Mode
RoHS Compliant and Halogen Free
Applications
Mobile Phones and Handheld Devices
STB, Cable Modem, and xDSL Platforms
WLAN ASIC Power / Storage (SSD and HDD)
General Purpose for POL LV Buck Converter
Simplified Application Circuit
VIN
RPGOOD
PGOOD
Enable
VIN LX
CIN
RT5785A/B
PGOOD
FB
EN
PGND
VOUT
AGND
L
VOUT
R1
CFF
COUT
R2
Copyright ©2017 Richtek Technology Corporation. All rights reserved.
DS5785A/B-02 April 2017
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1

RT5785A
RT5785A/B
Ordering Information
RT5785
Package Type
J8F : TSOT-23-8 (FC)
Lead Plating System
G : Green (Halogen Free and Pb Free)
PSM/PWM
A : PSM/PWM
B : Force-PWM
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.
Pin Configuration
(TOP VIEW)
87 6 5
2 34
TSOT-23-8 (FC)
Marking Information
RT5785AGJ8F
0N=DNN
0N= : Product Code
DNN : Date Code
RT5785BGJ8F
0M=DNN
0M= : Product Code
DNN : Date Code
Functional Pin Description
Pin No.
1
2
3
4
5
6
7
8
Pin Name
PGOOD
VIN
LX
PGND
VOUT
AGND
FB
EN
Pin Function
Power good indicator output. This pin is an open-drain logic output that is pulled to
ground when the output voltage is lower or higher than its specified threshold under
the conditions of UVP, OTP, dropout, EN shutdown, or during slow start.
Supply input. Supplies the power to the internal control circuit as well as the power
switches of the device. Drive VIN with a 2.5V to 6V power source and bypass VIN to
PGND with a suitably large capacitor to eliminate noise on the input to the IC.
Switch node. LX is the switching node that supplies power to the output and connect
the output LC filter from LX to the output load.
Power ground. This pin must be soldered to a large PCB and connected to analog
ground for maximum power dissipation.
Output voltage sense input. This pin is used to monitor and adjust output voltage for
superior load transient regulation.
Analog ground. Provides the ground return path for control circuitry and internal
reference.
Feedback voltage input. This pin is used to set the desired output voltage via an
external resistive divider. The feedback reference voltage is 0.6V typically.
Enable control input. Connecting this pin to logic high can enable the device and
connecting this pin to GND can disable the device.
Copyright ©2017 Richtek Technology Corporation. All rights reserved.
www.richtek.com
2
is a registered trademark of Richtek Technology Corporation.
DS5785A/B-02 April 2017


Features ® RT5785A/B 2A, 6V, 1.5MHz, 25μA IQ, ACOTTM Synchronous Step-Down Converter General Description The RT5785A/B is a high-performance, Advanced Constant On -Time (ACOTTM) monolithic synchronous s tep-down DC-DC converter that can deliv er up to 2A output current from a 2.5V to 6V input supply. The proprietary ACO T control architecture features quick t ransient response and provides stable o peration with small ceramic output capa citors and without complicated external compensation. The switching ripple vol tage is easily smoothed–out by small package filtering elements due to a con stant switching frequency of 1.5MHz and the maximum duty cycle of 100% allows the device to operate at low dropout us e. With internal low on-resistance powe r switches and extremely low quiescent current, the RT5785A/B displays excelle nt efficiency and good behavior across a range of applications. Cycle-by-cycle current limit provides protection agai nst shorted outputs, input under-voltage lock-out, output under-vol.
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