RY3750
1.2MHz, 30V, Step-Up Converter
Features
•
•
•
•
2.5V to 5.5V Input Voltage
1.23V Feedback Voltage
1.2MHz Fixed Switching Frequency
Internal 0.6A Switch Current Limit
•
•
•
Internal Compensation
Thermal Shutdown
Available in a 5-pin SOT-23 package
Applications
•
•
Camera Flash White LED
Digital still cameras
•
PDA LED back light
General Description
The Y3750 is a step-up converter. Its 1.23V feedback voltage reduces power loss and improves efficiency.
Optimized operation frequency can meet the requirement of small LC filters value and low operation current with
high efficiency. Internal soft start function can reduce the inrush current. Tiny package type provides the best
solution for PCB space saving and total BOM cost.
Typical Application
Circuit
V
IN
L
1
D1
V
OUT
VIN
SW
R
1
C
FF
RY3750
FB
C
OUT
C
IN
ON/
OFF
EN
GND
R
2
Figure1. Basic Application Circuit
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RY3750
1.2MHz, 30V, Step-Up Converter
Package and Pin Description
TOP VIEW
LX
1
5
IN
GND
2
FB
3
SOT23-5
4
EN
Top Marking: KFYLL (device code: KF, Y=year code, LL= lot number code)
Pin
1
2
3
4
5
Name
LX
GND
FB
EN
IN
Function
Power Switch Output. LX is the drain of the internal MOSFET switch. Connect the
power inductor and output rectifier to LX. LX can swing between GND and 30V.
Ground Pin
Feedback Input. The FB voltage is 1.23V. Connect a resistor divider to FB.
Regulator On/Off Control Input. A high input at EN turns on the converter, and a
low input turns it off. When not used, connect EN to the input supply for automatic
startup.
Input Supply Pin. Must be locally bypassed.
Order Information
Marking
KFYLL
Part No.
70390005
Model
RY3750
Description
RY3750 Step-up Converter, 2.5-5.5V, Vout
30V, 1.2MHz, SOT23-5
Package
SOT23-5
T/R Qty
3000PCS
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RY3750
1.2MHz, 30V, Step-Up Converter
Absolute Maximum Ratings
Parameter
V
IN
, V
EN
V
SW
All Other Pins
Continuous Power Dissipation(T
A
=+25℃)
Junction Temperature
Operating Temperature Range
Lead Temperature
Storage Temperature
Thermal Resistance θ
JA
Thermal Resistance θ
JC
Absolute Maximum Ratings
-0.3 to 6
-0.3 to 30
-0.3 to 6
0.6
150
-40 to 85
260
-65 to 150
250
130
Unit
V
V
V
W
°C
°C
°C
°C
°C /W
°C /W
Recommended Operating Conditions
Parameter
Supply Voltage V
IN
Output Voltage V
OUT
Operating Junction Temp.(T
J
)
Recommended
2.5 to 5.5
V
IN
to 30
-40 to 125
Unit
V
V
°C
Electrical Characteristics
Parameter
Supply
Current(Shutdown)
Quiescent Current
SW Leakage
SW On Resistance
Operating Input Voltage
Current Limit
Oscillator Frequency
Maximum Duty Cycle
Feedback Voltage
FB Input Bias Current
EN Threshold
Thermal Shutdown
Supply
Current(Shutdown)
Symbol
I
IN
Test Conditions
V
EN
=0V
V
FB
=1V, switch
V
SW
= 20V
2.5
I
LIMIT
f
SW
D
MAX
V
FB
V
EN
I
IN
V
EN
=0V
V
IN
= 4V, Duty cycle=50%
V
FB
=1V
V
FB
=1.23V
1.21
-50
0.6
1.2
90
1.23
-10
1
160
0.1
Min
Typ
0.1
0.15
400
Max
1
0.3
1
650
5.5
Unit
µA
mA
µA
mΩ
V
A
MHz
%
V
nA
V
°C
µA
1.25
1
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RY3750
1.2MHz, 30V, Step-Up Converter
Typical Performance Characteristics
Note (1): Performance waveforms are tested on the evaluation board.
Note (2): V
IN
=5V, V
OUT
=24V, L = 10µH, C
OUT
=22uF T
A
= +25ºC, unless otherwise noted
Efficiency vs Output Current
V
OUT
= 24V
Load Regulation
V
OUT
= 24V
Line Regulation
V
OUT
= 24V, I
OUT
= 60mA
Current Limit vs Duty
V
IN
=5V
Output Ripple Voltage
I
OUT
= 0mA
Output Ripple Voltage
I
OUT
= 60mA
Output Ripple Voltage
I
OUT
= 120mA
V
IN
Power On
I
OUT
= 60mA
V
IN
Power Off
I
OUT
= 60mA
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RY3750
1.2MHz, 30V, Step-Up Converter
EN Power On
I
OUT
= 60mA
EN Power Off
I
OUT
= 60mA
Load Transient
V
IN
=5V, I
OUT
=50mA to 100mA@300mA/µs
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