RY3420
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©RYCHIP Semiconductor Inc.
5.5V 2A 1.2MHz Synchronous Step-Down Regulator
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Features
• 2.7V to 5.5V Input Voltage Range
• 2A Continuous Output Current
• 1.2MHz Switching Frequency
• Built-in Short Protection
• Built-in Over Current Limit
• Built-in Over Voltage Protection
• PFM Mode for High Efficiency in Light Load
• High Efficiency: Up to 96%
• Output Adjustable from 0.6V
• No Schottky Diode Required
• Over Temperature Protected
• Low Quiescent Current: 40μA
• Available in SOT23-5 package
• -40°C to +85°C Temperature Range
Applications
• Cellular and Smart Phones
• Wireless and DSL Modems
• Portable Instruments
• Digital Still and Video Cameras
General Description
The RY3420 is a high-efficiency monolithic synchronous buck regulator using a constant frequency, current mode
architecture. The device is available in an adjustable version. Supply current with no load is 40uA and drops to
<1uA in shutdown. The 2.7V to 5.5V input voltage range makes the RY3420 ideally suited for single Li-Ion battery
powered applications. 100% duty cycle provides low dropout operation, extending battery life in portable systems.
PWM/PFM mode operation provides very low output ripple voltage for noise sensitive applications. Switching
frequency is internally set at 1.2MHz, allowing the use of small surface mount inductors and capacitors. Low output
voltages are easily supported with the 0.6V feedback reference voltage.
The RY3420 requires a minimal number of readily available, external components and is available in a space saving
SOT23-5 package.
Typical Application Circuit
L
1
C
OUT
R
1
R
2
C
IN
IN SW
EN FB
GND
V
IN
V
OUT
ON/
OFF
C
FF
Basic Application Circuit