SE3508 [SEAWARD]
1MHz, 5A Step-up Current Mode PWM Converter;
| 型号： | SE3508 |
| 厂家： | 
Seaward Electronics Inc. |
| 描述： | 1MHz, 5A Step-up Current Mode PWM Converter |
| 文件： | 总7页 (文件大小：537K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
General Description
Features
The SE3508 is a current mode boost DC-DC
converter. Its PWM circuitry with built-in 0.16Ω power
MOSFET make this regulator highly power efficient.
The internal compensation network also minimizes as
Adjustable Output up to 6V
Internal Fixed PWM frequency: 1.0MHz
Precision Feedback Reference Voltage: 1.275V
(±2%)
much as
6
external component counts. The
Internal 0.16Ω, 5A, 6V Power MOSFET
Shutdown Current: 0.1μA
non-inverting input of error amplifier connects to a
1.275V precision reference voltage and internal
soft-start function can reduce the inrush current. The
SE3508 is available in the PSOP8 package.
Over Temperature Protection
Over Voltage Protection
Adjustable Over Current Protection: 0.5A ~ 5A
Package: PSOP8
Application
Chargers
LCD Displays
Digital Cameras
Handheld Devices
Portable Products
Typical Application
Rev1.0
Preliminary and all contents are subject to change without prior notice.
© Seaward Electronics, Inc. • www.seawardinc.com.cn • Page 1
Pin Configuration
Pin Description
Number
Pin
PGND
OC
Pin Function Description
IC Ground
1
2
3
4
5
6
7
8
Adjustable Current Limit
Input power supply pin
Enable Control (Active High)
Power ground
VCC
EN
GND
FB
Error Amplifier Inverting Input
Not Connected
NC
Power Switch Output
SW
Note: Exposed PAD-Must connect to Ground
Rev1.0
Preliminary and all contents are subject to change without prior notice.
© Seaward Electronics, Inc. • www.seawardinc.com.cn • Page 2
Functional Block Diagram
Ordering Information
Marking Information
Package
Part Number
Remarks
SE3508
YYWW means Production batch
LF means Lead Free.
SE3508-LF
PSOP8
YYWW-LF
Absolute Maximum Ratings
Parameter
Supply Voltage VCC
Symbol
VCC
Maximum
Units
V
6
6
SW Voltage
VSW
V
FB, EN Voltage
6
V
θJA
TJ
Thermal Resistance
Junction Temperature
Operating Temperature
Storage Temperature
Lead Temperature (Soldering, 10 sec)
+83
°C /W
°C
+150
-40 to +85
-65 to 150
+260
TOP
TST
°C
°C
°C
Rev1.0
Preliminary and all contents are subject to change without prior notice.
© Seaward Electronics, Inc. • www.seawardinc.com.cn • Page 3
Recommended Operating Conditions
Parameter
Supply Voltage
Symbol
VCC
Min
2.8
Typ
Max
5.5
Unit
V
Operating Temperature Range
TA
-40
+85
℃
Electrical Characteristics
VIN = 3.3V, TA= 25℃; unless otherwise specified
Symbol
Parameter
Test Conditions
Min
Typ
Max
Unit
System Supply Input
VCC
Input Supply Range
Under Voltage Lockout
UVLO Hysteresis
2.8
5.5
V
V
VUVLO
2.6
0.1
260
2
V
ICC
ICC
Quiescent Current
VFB=1.3V, No switching
VFB=1.2V, Switching
VEN=GND
uA
mA
μA
Average Supply Current
Shutdown Supply Current
ICC
0.1
Oscillator
FOSC
Operation Frequency
Frequency Change with Voltage
Maximum Duty Cycle
VFB=1.0V
MHZ
%
0.8
1.0
5
1.2
1.3
0.7
VCC=2.6V to 5.5V
△f / △V
TDUTY
90
%
Reference Voltage
VREF
Reference Voltage
Line Regulation
1.25 1.275
0.05
V
VCC=2.6V~5.5V
%/V
Enable Control
VEN
Enable Voltage
0.9
V
V
VEN
Shutdown Voltage
MOSFET
RDS (ON)
Protection
IOCP
On Resistance of Driver
ILX=2A
0.16
Ω
OCP Current
Adjustable OCP Current
OTP Temperature
With External Resistor：8k
5
A
A
IOCP
With External Resistor：8k~80k
0.5
5
TOTP
+150
℃
Rev1.0
Preliminary and all contents are subject to change without prior notice.
© Seaward Electronics, Inc. • www.seawardinc.com.cn • Page 4
0.5A. Keep traces at this pin as short as possible. Do
Operation
The SE3508 is a current mode boost converter. The not put capacitance at this pin. To set the over current
constant switching frequency is 1MHz and operates trip point according to the following equation:
with pulse width modulation (PWM). Build-in 6V / 5A
40000
IOCP
MOSFET provides a high output voltage. The control
loop architecture is peak current mode control;
R3
Over Temperature Protection (OTP)
therefore slope compensation circuit is added to the SE3508 will turn off the power MOSFET automatically
when the internal junction temperature is over 150℃.
The power MOSFET wake up when the junction
temperature drops 30℃ under the OTP threshold
current signal to allow stable operation for duty cycles
larger than 50%.
Soft Start Function
Soft start circuitry is integrated into SE3508 to avoid temperature.
inrush current during power on. After the IC is
Over Voltage Protection (OVP)
enabled, the output of error amplifier is clamped by In some condition, the resistive divider may be
the internal soft-start function, which causes PWM unconnected, which will cause PWM signal to operate
pulse width increasing slowly and thus reducing input with maximum duty cycle and output voltage is
surge current.
boosted higher and higher. The power MOSFET will
be turned off immediately, when the output voltage
Current Limit Program
A resistor between OC and GND pin programs peak exceeds the OVP threshold level. The SE3508’s OVP
switch current. The resistor value should be between threshold is 6V.
8k and 80k. The current limit will be set from 5A to
Application Information
Inductor Selection
Inductance value is decided based on different condition. 3.3uH to 4.7μH 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 avoids 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 ratings 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
Rev1.0
Preliminary and all contents are subject to change without prior notice.
© Seaward Electronics, Inc. • www.seawardinc.com.cn • Page 5
The output voltage is set by a resistive voltage divider from the output voltage to FB. The output voltage is:
R1
R2
VOUT 1.275V 1
Layout Considerations
1. The power traces, consisting of the GND trace, the SW trace and the VCC trace should be kept short, direct
and wide.
2.SW、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, SW.
6. The GND of the IC, CIN and COUT should be connected close together directly to a ground plane.
Rev1.0
Preliminary and all contents are subject to change without prior notice.
© Seaward Electronics, Inc. • www.seawardinc.com.cn • Page 6
Outline Drawing For PSOP8
联系方式：
北京思旺电子技术有限公司–中国总部
地址：中国北京市海淀区信息路 22 号上地科技综合楼 B 座二层
邮编：100085
电话:010-82895700/1/5
传真:010-82895706
Seaward Electronics Corporation – 台湾办事处
2F, #181, Sec. 3, Minquan East Rd,
Taipei, Taiwan R.O.C
电话: 886-2-2712-0307
传真: 886-2-2712-0191
Seaward Electronics Incorporated – 北美办事处
1512 Centre Pointe Dr.
Milpitas, CA95035, USA
电话: 1-408-821-6600
Rev1.0
Preliminary and all contents are subject to change without prior notice.
© Seaward Electronics, Inc. • www.seawardinc.com.cn • Page 7
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