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SD6271
1MHz, 2A Step-Up Current Mode PWM Converter
General Description
The SD6271 is a current mode boost DC-DC conv
power MOSFET make this regulator highly power efficient. The internal compensation network also
minimizes as much as 6 external component counts. The non-inverting input of error amplifier connects
erter. Its PWM circuitry with built-in 0.25
Ω
to a 0.6V precision reference voltage and internal soft-start function can reduce the inrush current.
The SD6271 is available in the SOT23-6L pa
application fields.
ckage and provides space-saving PCB for the
Features
Adjustable Output up to 24V
Internal Fixed PWM frequency: 1.0MHz
Precision Feedback Reference Voltage: 0.6V (±2%)
Internal 0.25
Shutdown Current: 0.1μA
Over Voltage Protection
Over Temperature Protection
Adjustable Over Current Protection: 0.5A ~ 2.5A
Package: SOT23-6L
, 2A, 26V Power MOSFET
Ω
Applications
Chargers
LCD Displays
Digital Cameras
Handheld Devices
Portable Products
T ypical Application Circuit
SD6271
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Function Block Diagram
SD6271
Pin Descriptions
SOT23-6L
Top View
AL*AL***
AL**
LX
GND
FB
1
2
3
**
*
*
*
*
6
OC
5
EN
4
Name No. I / O Description
LX 1 O Power Switch Output
GND 2 P IC Ground
FB 3 I Error Amplifier Inverting Input
EN 4 I Enable Control (Active High)
VCC 5 P IC Power Supply
OC 6 I Adjustable Current Limit (Floating Available)
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r
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Marking Information
SOT23-6L
AL* **
AL* **
**
Lot Number
year
Part Number Code
SD6271
Lot Numbe
Yea
: Production year’s last digit
Part Number Code: Part number identification code for this product. It should be always “AL”.
: Wafer lot number’s last two digits
For Example: 132386TB 86
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SD6271
Ordering Information
Part Number Code Operating Temperature Package MOQ Description
SD6271LR-G1 AL
-40°C ~ 85°C
SOT23-6L 3000EA Tape & Reel
Absolute Maximum Ratings
Parameter Symbol Conditions
Supply Voltage VCC 0 6 V
Min. Typ. Max.
Unit
OVP Voltage V
LX Voltage VLX 0 28 V
EN,FB Voltage 0 6 V
Power Dissipation PD
Thermal Resistance (Note1) θJA SOT23-6L +220
Junction Temperature TJ +150
Operating Temperature TOP -40 +85
Storage Temperature TST -65 +150
Lead Temperature (soldering, 10 sec) +260
Note1:
is measured in the natural convection at TA=25°C on a low effective thermal conductivity test
θ
JA
board of JEDEC 51-3 thermal measurement standard.
0 28 V
OVP
SOT23-6L @T
=25°C
A
455 mW
°C / W
°C
°C
°C
°C
IR Re-flow Soldering Curve
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SD6271
Recommended Operating Conditions
Parameter Symbol Conditions
Supply Voltage VIN 2.6 5.5 V
Operating Temperature Range TA Ambient Temperature -40 +85
DC Electrical Characteristics
Parameter Symbol Conditions
System Supply Input
Input Supply Range VCC 2.6 5.5 V
Under Voltage Lockout V
UVLO Hysteresis 0.1 V
Quiescent Current ICC VFB=0.66V, No switching 0.16 mA
Average Supply Current ICC VFB=0.55V, Switching 2.84 mA
Shutdown Supply Current ICC VEN=GND 0.1 µA
Oscillator
Operation Frequency F
Frequency Change with Voltage f△ / V△ VCC=2.7V to 5.5V 5 %
Maximum Duty Cycle T
Reference Voltage
Feedback Voltage
Line Regulation
Enable Control
Enable Voltage VEN
UVLO
OSC
DUTY
V
REF
(VCC=3.3V, TA=25
2.2 V
VFB=1.0V 0.8 1.0 1.2 MHZ
90 %
0.588 0.6 0.612 V
V
=2.7V～5.5V
CC
Min. Typ. Max.
°C
,unless otherwise specified)
Min. Typ. Max.
0.05 % / V
0.96 V
Unit
°C
Unit
Shutdown Voltage VEN
MOSFET
On Resistance of Driver R
Protection
OVP Threshold Voltage V
OVP Sink Current I
OCP Current I
Adjustable OCP Current I
OTP Temperature T
DS (ON) ILX
OVP
SINK
OCP
OCP
OTP
=2A 0.25
27 V
5 µA
2 2.6 A
With External Resistor：
10k~100k
+150
0.6 V
Ω
0.5
2.6
°C
A
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Function Description
Operation
SD6271
The SD6271 is a current mode boost converter.
operates with pulse width modulation (PWM). Build-in 26V / 2A MOSFET provides a high output
voltage. The control loop architecture is peak current mode control; therefore slope compensation
circuit is added to the current signal to allow stable operation for duty cycles larger than 50%.
The constant switching frequency is 1MHz and
Soft Start Function
Soft start circuitry is integrated into SD6271 to av
is enabled, the output of error amplifier is clamped by the internal soft-start function, which causes
PWM pulse width increasing slowly and thus reducing input surge current.
oid inrush current during power on. After the IC
Current Limit Program
A resistor between OC and GND pin programs peak switch current. The resistor value should be
between 10k and 100k. The current limit will be set from 2.5A to 0.5A. Keep traces at this pin as short
as possible. Do not put capacitance at this pin. To set the over current trip point according to the
following equation:
48000
I
OCP
Over Voltage Protection (OVP)
3R
In some condition, the resistive divider may be unconnected, which will cause PWM signal to
operate with maximum duty cycle and power switch voltage is boosted higher and higher. The power
MOSFET will be turned off immediately, when the power switch voltage exceeds the OVP threshold
level. The SD6271’s OVP threshold is 27V.
Over Temperature Protection (OTP)
SD6271 will turn off the power MOSFET automatically
over 150
threshold temperature.
°C
. The power MOSFET wake up when the junction temperature drops 30°C under the OTP
when the internal junction temperature is
Output Disconnect
When power on and the EN pin will be pulled
external PMOS is turned on and current through it for output loading. While output loading is increase,
output voltage is drop. When the FB pin voltage is under 0.3V, the EN pin sinks 20µA current, the
external PMOS will be turn off. The output short condition will be disconnected.
high. The SD6271 start up and operates. The
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SD6271
Application Information
Inductor Selection
Inductance value is decided based on different condition. 4.7 to 22µH inductor value is
recommended for general application circuit. There are three important inductor specifications, DC
resistance, saturation current and core loss. Low DC resistance has better power efficiency. Also, it
avoid inductor saturation which will cause circuit system unstable and lower core loss at 1 MHz.
Capacitor Selection
The output capacitor is required to maintain the DC voltage. Low ESR capacitors are preferred to
reduce the output voltage ripple. Ceramic capacitor of X5R and X7R are recommended, which have
low equivalent series resistance (ESR) and wider operation temperature range.
Diode Selection
Schottky diodes with fast recovery times and low forward voltages are recommended. Ensure the
diode average and peak current rating exceed the average output current and peak inductor current. In
addition, the diode’s reverse breakdown voltage must exceed the output voltage.
Output Voltage Programming
The output voltage is set by a resistive voltage divider from the output voltage to FB. The output
voltage is:
1R
OUT
1V6.0V
2R
Layout Considerations
1. The power traces, consisting of the GND trace, the LX trace and the VCC trace should be kept
short, direct and wide.
2. LX、L and D switching node, wide and short trace to reduce EMI.
3. Place CIN near VCC pin as closely as possible to maintain input voltage steady and filter out the
pulsing input current.
4. The resistive divider R1and R2 must be connected to FB pin directly as closely as possible.
5. FB is a sensitive node. Please keep it away from switching node, LX.
6. The GND of the IC, CIN and C
plane.
should be connected close together directly to a ground
OUT
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T ypical Application
SD6271
SD6271
General Boost Converter
SD6271
SCP Detect and Load Disconnect
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Package Outline
SOT23-6L
SD6271
Note:
1. Package dimensions are in compliance with JEDEC outline: MO-178 AB.
Symbols Min. (mm) Max. (mm)
A 1.050 1.450
A1 0.050 0.150
A2 0.900 1.300
b 0.300 0.500
c 0.080 0.220
D 2.900 BSC
E 2.800 BSC
E1 1.600 BSC
e 0.950 BSC
e1 1.900 BSC
L 0.300 0.600
L1 0.600 REF
L2 0.250 BSC
θ°
θ1°
θ2°
0° 8°
3° 7°
6° 15°
Unit: mm
2. Dimension “D” does not include molding flash, protrusions or gate burrs.
3. Dimension “E1” does not include inter-lead flash or protrusions.
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