RY3420
5.5V 2A 1.2MHz Synchronous Step-Down Regulator
Features
•
•
•
•
•
•
High Efficiency: Up to 96%
2.5V to 5.5V Input Voltage Range
1.2MHz Constant Frequency Operation
No Schottky Diode Required
Low Dropout Operation: 100% Duty Cycle
PFM Mode for High Efficiency in Light Load
•
•
•
•
•
•
Over Temperature Protected
Low Quiescent Current: 40μA
Short Circuit Protection
Inrush Current Limit and Soft Start
2A Continuous Output Current
SOT23-5 package
Applications
•
•
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Cellular and Smart Phones
Wireless and DSL Modems
PDAs
•
•
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Portable Instruments
Digital Still and Video Cameras
PC Cards
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 2.5V to5.5V 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 is offered in a low profile (1mm) 5-pin, thin SOT package, and is available in an adjustable version.
Typical Application
Circuit
L
1
V
IN
4
IN
SW
3
V
OUT
R
1
C
FF
C
OUT
Opt.
C
IN
ON/
OFF
1
EN
GND
2
FB
5
R
2
Basic Application Circuit
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RY3420
5.5V 2A 1.2MHz Synchronous Step-Down Regulator
Pin Description
Pin Configuration
TOP VIEW
EN
1
5
FB
GND
2
SW
3
4
IN
SOT23-5
Top Marking: ADYLL (device code: AD, Y=year code, LL= lot number code)
Pin Description
Pin
1
2
3
4
5
Name
EN
GND
SW
IN
FB
Function
Chip Enable Pin. Drive EN above 1.5V to turn on the part. Drive EN below 0.3V to
turn it off. Do not leave EN floating.
Ground Pin
Power Switch Output. It is the switch node connection to Inductor. This pin connects
to the drains of the internal P-ch and N-ch MOSFET switches.
Power Supply Input.
Must be closely decoupled to GND with a 10µF or greater
ceramic capacitor.
Output Voltage Feedback Pin. An internal resistive divider divides the output voltage
down for comparison to the internal reference voltage.
Order Information
Marking
ADYLL
Part No.
70301003
Model
RY3420
Description
RY3420 Buck, 2.5-5.5V, 2A, 1.2MHz,
VFB 0.6V, SOT23-5
Package
SOT23-5
MOQ
3000PCS
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RY3420
5.5V 2A 1.2MHz Synchronous Step-Down Regulator
Absolute Maximum Ratings
(1)(2)
Input Supply Voltage ……… -0.3V to 6.0V
Operating Temperature Range ………...... -40° to +85°
C
C
EN, FB Voltages……........... -0.3V to 6.0V
Junction Temperature(Note2) ………………...…... 125°C
SW Voltage……….… -0.3V to (Vin+0.3V)
Storage Temperature Range ...…...…...…. -65° to 150°
C
C
Peak SW Sink and Source Current ……3A
Lead Temperature(Soldering,10s).………………. +300°C
Thermal Resistance ( θJA) …… 170 °
C/W
Thermal Resistance（θJC） SOT23-5………… 130 °
C/W
ESD(Human Body Made)HMB………2KV
ESD (Machine Made)MM…………………………200V
Note (1): Exceeding these ratings may damage the device.
Note (2): The device is not guaranteed to function outside of its operating conditions.
Electrical Characteristics
(1)(2)
(V
IN
=V
EN
=3.6V, T
A
= 25°C, unless otherwise noted.)
Parameter
Input Voltage Range
UVLO Threshold
FB = 90%, Iload=0mA
Input DC Supply Current
Regulated Feedback Voltage
Reference Voltage Line
Regulation
Output Voltage Line
Regulation
Output Voltage Load
Regulation
Oscillation Frequency
On Resistance of PMOS
On Resistance of NMOS
Peak Current Limit
EN up Threshold
EN Threshold Hysteresis
EN Leakage Current
SW Leakage Current
Soft Start
Thermal Shutdown
Thermal Hysteresis
160
20
V
EN
=0V, V
IN
=Vsw=5V
RY3420
RY3420B
I
SW
=100mA
I
SW
=-100mA
V
IN
= 3.6V, FB=90%
V
EN
-Rising
3
1.05
1.15
140
±0.01
±0.01
±1.0
±1.0
1.2
1.25
Vin = 2.5V to5.5V
V
IN
= 2.5V to 5.5V
FB= 105%, Iload=0mA
V
EN
= 0V, V
IN
=4.2V
0.588
Conditions
Min.
2.5
2.3
150
40
0.1
0.600
0.04
0.04
0.5
1.2
2.4
0.1
0.08
300
70
1.0
0.612
0.40
0.4
Typ.
Max.
5.5
Unit
V
V
µA
µA
µA
V
%/V
%
%
MHz
MHz
Ω
Ω
A
V
mV
µA
µA
mS
℃
℃
Note (1): MOSFET on-resistance specifications are guaranteed by correlation to wafer level measurements.
Note (2): Thermal shutdown specifications are guaranteed by correlation to the design and characteristics analysis.
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RY3420
5.5V 2A 1.2MHz Synchronous Step-Down Regulator
Typical Performance Characteristics
Note (1): Performance waveforms are tested on the evaluation board.
Note (2): V
IN
=5V, V
OUT
=3.3V, T
A
= +25ºC, unless otherwise noted.
Efficiency vs Load Current
V
OUT
= 3.3V, 1.2V
Load Regulation
V
OUT
= 3.3V, 1.2V
Line Regulation
V
OUT
= 3.3V
Output Ripple Voltage
V
IN
=5V, V
OUT
=3.3V, I
OUT
=0A
Output Ripple Voltage
V
IN
=5V, V
OUT
=3.3V, I
OUT
=1A
Output Ripple Voltage
V
IN
=5V, V
OUT
=3.3V, I
OUT
=2A
Loop Response
V
IN
= 5V, V
OUT
= 3.3V, I
INDUCTOR
=1A-2A
Hiccup with Output Short
V
IN
= 5V, V
OUT
= 3.3V
Short Circuit Entry
V
IN
= 5V, V
OUT
= 3.3V
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RY3420
5.5V 2A 1.2MHz Synchronous Step-Down Regulator
Short Circuit Recovery
V
IN
= 5V, V
OUT
= 3.3V
Enable Startup at No Load
V
IN
= 5V, V
OUT
= 3.3V
Enable Shutdown at No Load
V
IN
= 5V, V
OUT
= 3.3V
Enable Startup at Full Load
V
IN
= 5V, V
OUT
= 3.3V, I
INDUCTOR
=2A
Enable Shutdown at Full Load
V
IN
= 5V, V
OUT
= 3.3V, I
INDUCTOR
=2A
Power Up at No Load
V
IN
= 5V, V
OUT
= 3.3V, I
INDUCTOR
=0A
Power Up at Full Load
V
IN
= 5V, V
OUT
= 3.3V, I
INDUCTOR
=2A
Email: support@rychip.com
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