FOSLINK FSP3133SAG Pwm control 2a step-down converter Datasheet

PWM CONTROL 2A STEP-DOWN CONVERTER
FSP3133
„ FEATURES
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„ GENERAL DESCRIPTION
Input voltage: 3.6V to 23V.
Output voltage: 0.8V to VCC.
Duty ratio: 0% to 100% PWM control
Oscillation frequency: 300KHz typ.
Soft-start, Current limit, Enable function
Thermal Shutdown function
Built-in internal SW P-channel MOSFET
SOP8L Package.
„ TYPICAL APPLICATION
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PC Motherboard
LCD Monitor
Graphic Card
DVD-Video Player
Telecom Equipment
ADSL Modem
Printer and other Peripheral Equipment
Microprocessor core supply
Networking power supply
„ PIN ASSIGNMENT
(Top View)
FB 1
8 VSS
EN 2
7 VSS
OCSET 3
6
VCC 4
FSP3133 consists of step-down switching regulator
with PWM control. These devices include a
reference voltage source, oscillation circuit, error
amplifier and internal PMOS.
FSP3133 provides low-ripple power, high efficiency,
and excellent transient characteristics. The PWM
control circuit is able to vary the duty ratio linearly
from 0 up to 100%. This converter also contains an
error amplifier circuit as well as a soft-start circuit
that prevents overshooting at startup. An enable
function, an over current protect function and a
short circuit protect function are built inside, and
when OCP or SCP happens, the operation
frequency will be reduced from 300KHz to 30KHz.
Also, an internal compensation block is built in to
minimum external component count.
With the addition of an internal P-channel Power
MOS, a coil, capacitors, and a diode connected
externally, these ICs can function as step-down
switching regulators. They serve as ideal power
supply units for portable devices when coupled with
the
SOP8L mini-package,
providing
such
outstanding features as low current consumption.
Since this converter can accommodate an input
voltage up to 23V, it is also suitable for the operation
via an AC adapter.
OUTPUT
5 OUTPUT
„ PIN DESCRIPTION
Pin Number Pin Name
1/7
Pin Description
1
FB
Feedback Pin
2
EN
Enable Input Pin
H: Normal operation(Step-down operation)
L: Step-down operation stopped(All circuits deactivated)
3
OCSET
4
VCC
5,6
OUTPUT
7,8
VSS
Add an external resistor to set max output current
IC power supply pin
Switch pin. Connect external inductor/diode here. Minimize trace area at this pin to
reduce EMI.
GND pin
2007-6-22
PWM CONTROL 2A STEP-DOWN CONVERTER
FSP3133
„
ABSOLUTE MAXIMUM RATINGS(NOTE)
Parameter
VCC Pin Voltage, VCC
Value
VSS-0.3 to VSS+25
Unit
V
Feedback Pin Voltage, VFB
VSS-0.3 to VCC
V
EN Pin Voltage, VEN
Switch Pin Voltage, VOUTPUT
Power Dissipation, PD
VSS-0.3 to VIN + 0.3
VSS-0.3 to VIN + 0.3
Internally limited
V
V
mW
Operating Temperature Range, TOPR
-20 to +125
°C
Storage Temperature Range, TSTG
-40 to +150
°C
Note: Do not exceed these limits to prevent damage to the device. Exposure to absolute maximum rating conditions
for long periods may affect device reliability.
„
ELECTRICAL CHARACTERISTICS
(VIN = 12V, TA= 25°C, unless otherwise specified.)
Parameter
Symbol
Input Voltage
VIN
Feedback Voltage
VFB
Feedback Bias Current
Switch Current
Current Consumption During
Power Off
Line Regulation
Load Regulation
Oscillation Frequency
Frequency of Current Limit or
Short Circuit Protect
IFB
ISW
Enable Pin Input Voltage
2/7
ISSS
Test Conditions
Min.
IIOUT= 0.1A
IIOUT= 0.1A
0.784
VEN = 0
Measure waveform at SW pin
10
VSH
Evaluate oscillation at SW pin
Evaluate oscillation stop at
SW pin
2.0
OCSET Pin Bias Current
IOCSET
Soft-Start Time
TSS
Internal MOSFET Rdson
Rdson
Efficiency
EFFI
Thermal Resistance
Junction to Ambient
θJA
23
V
0.8
0.816
V
0.1
0.5
µA
A
10
fosc1
ISH
ISL
Unit
2.5
240
Enable Pin Input Leakage
Current
Max.
3.6
VIN =5V~23V
ΔVOUT /VOUT
I
ΔVOUT /VOUT
IOUT= 0.1A~2A
Measure waveform at SW pin
fosc
VSL
Typ.
VIN =5V, VFB = 0
VIN =12V, VFB = 0
VIN =12V, VOUT =5V,
IIOUT= 2A
1
0.2
300
µA
2
0.5
360
%
%
KHz
KHz
0.8
V
75
20
-10
90
105
µA
0.3
1
2
ms
110
70
150
100
mΩ
µA
92
%
65
°C/W
2007-6-22
PWM CONTROL 2A STEP-DOWN CONVERTER
FSP3133
„
FUNCTIONAL BLOCK DIAGRAM
„
FUNCTIONAL DESCROPTION
PWM Control
The FSP3133 consists of DC/DC converters that employ a pulse-width modulation (PWM) system. In converters of
the FSP3133, the pulse width varies in a range from 0 to 100%, according to the load current. The ripple voltage
produced by the switching can easily be removed through a filter because the switching frequency remains constant.
Therefore, these converters provide a low-ripple power over broad ranges of input voltage and load current.
Under Voltage Lockout
The under voltage lockout circuit of the FSP3133 assures that the high-side MOSFET driver outputs remain in the off
state whenever the supply voltage drops below 3.3V. Normal operation resumes once VCC rises above 3.5V.
RDS(ON) Current Limiting
The current limit threshold is setting by the external resistor connecting from VCC supply to OCSET. The internal
100uA sink current crossing the resistor sets the voltage at the pin of OCSET. When the PWM voltage is less than the
voltage at OCSET, an over-current condition is triggered.
I
LOAD ×= R DS(ON) I OCSET × R OCSET
See above formula for setting the current limit value
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2007-6-22
PWM CONTROL 2A STEP-DOWN CONVERTER
FSP3133
„
TYPICAL APPLICATION CIRCUIT
Note: VOUT=VFB*(1+RA/RB)
RB=0.7KΩ~5KΩ
VIN=12V, IMAX=2A
VOUT
L1 Value
„
2.5V
22uH
3.3V
27uH
5V
33uH
TEST CIRCUITS
1) Enable Function Test
2) Feedback Function Test
3) Operation Function Test
4/7
2007-6-22
PWM CONTROL 2A STEP-DOWN CONVERTER
FSP3133
„ TYPICAL CHARACTERISTICS
5/7
2007-6-22
PWM CONTROL 2A STEP-DOWN CONVERTER
FSP3133
„ TYPICAL CHARACTERISTICS (CONTINUED)
„
ORDER INFORMATION
FSP3133XXXX
Package:
S: SOP8L
„
Output Voltage:
Blank: ADJ
Temperature Grade:
Packing:
Blank: Tube or Bulk G: -20~125℃
A: Tape & Reel
MARKING INFORMATION
Logo
FSP3133
Part number:
YYWWXX
Internal code
Date code:
YY: Year (01=2001)
WW: Nth week (01~52)
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2007-6-22
PWM CONTROL 2A STEP-DOWN CONVERTER
FSP3133
θ
H
PACKAGE INFORMATION
E
„
D
7ο(4х)
e
B
A
0.015х45ο
A1
A2
7ο(4х)
VIEW “A”
Symbol
A
A1
A2
B
C
D
E
e
H
L
θ
7/7
Dimensions In Millimeters
Nom.
Max.
1.60
1.75
0.25
1.45
1.50
0.41
0.51
0.20
0.25
5.05
5.30
3.90
4.10
1.27TYP.
5.80
5.99
6.20
0.38
0.71
1.27
0ο
8ο
Min.
1.40
0.10
1.30
0.33
0.19
4.80
3.70
Dimensions In Inches
Min.
Nom.
0.055
0.063
0..004
0.051
0.057
0.013
0.016
0.0075
0.008
0.189
0.199
0.146
0.154
0.050TYP.
0.228
0.236
0.015
0.028
0ο
2007-6-22
Max.
0.069
0.010
0.059
0.020
0.010
0.209
0.161
0.244
0.050
8ο
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