FOSLINK FSP3125S50E 150khzï¼ 2a pwm buck dc/dc converter Datasheet

150KHZ,2A PWM BUCK DC/DC CONVERTER
FSP3125
„ FEATURES
z Output voltage: 3.3V, 5V, 12V and adjustable
output version
z Adjustable version output voltage range, 1.23V to
18V ± 4%
z 150KHz ±15% fixed switching frequency
z Voltage mode non-synchronous PWM control
z Thermal-shutdown and current-limit protection
z ON/OFF shutdown control input
z Operating voltage can be up to 22V
z Output load current: 2A
z SOP8L packages
z Low power standby mode
z Built-in switching transistor on chip
„ Typical Application
z
z
z
Simple High-efficiency step-down regulator
On-card switching regulators
Positive to negative converter
„ GENERAL DESCRIPTION
The FSP3125 series are monolithic IC designed for a
step-down DC/DC converter, and own the ability of
driving a 2A load without additional transistor. It saves
board space. The external shutdown function can be
controlled by logic level and then come into standby
mode. The internal compensation makes feedback
control having good line and load regulation without
external design. Regarding protected function,
thermal shutdown is to prevent over temperature
operating from damage, and current limit is against
over current operating of the output switch. If current
limit function occurs and FB is down below 0.5V, the
switching frequency will be reduced. The FSP3125
series operates at a switching frequency of 150KHz
thus allow smaller sized filter components than what
would be needed with lower frequency switching
regulators. Other features include a guaranteed ± 4%
tolerance on output voltage under specified input
voltage and output load conditions, and ± 15% on the
oscillator frequency. The output version included fixed
3.3V, 5V, 12V, and an adjustable type. The chips are
available in a standard SOP8L package.
„ PIN ASSIGNMENT
(Top View)
VIN 1
8 GND
OUTPUT 2
FB
3
SD 4
7 GND
FSP3125
6
GND
5
GND
„ PIN DESCRIPTION
Name
VIN
OUTPUT
FB
SD
GND
GND
GND
GND
1/9
No.
1
2
3
4
5
6
7
8
Description
Operating Voltage Input
Switching Output
Output Voltage Feedback Control
On/Off Shutdown
Ground
Ground
Ground
Ground
2007-3-27
150KHZ,2A PWM BUCK DC/DC CONVERTER
FSP3125
„
ABSOLUTE MAXIMUM RATINGS
Parameter
Supply Voltage
On/Off Pin Input Voltage
Feedback Pin Voltage
Output Voltage to Ground
Power Dissipation
Storage Temperature
Operating Temperature
Operating Voltage
Value
+24
-0.3 to +18
-0.3 to +18
-1
Internally Limited
-65 to +150
-40 to +125
+4.5 to +22
Unit
V
V
V
V
W
℃
℃
V
„
ELECTRICAL CHARACTERISTICS
(Unless otherwise specified, VIN=12V for 3.3V, 5V and adjustable version and VIN=18V for the 12V version. ILOAD =
0.5A)
Parameter
Symbol
Feedback Bias Current
IFB
Oscillator Frequency
Fosc
Short Circuit Oscillator
Frequency
FCSP
Saturation Voltage
VSAT
Maximum Duty Cycle(On)
Minimum Duty Cycle(Off)
DC
Current Limit
ICL
Output
Leakage
Current
Output=-1
Quiescent Current
IQ
When Current Limit Occur and
VFB < 0.5V, TA=25°C
IOUT= 2A, No Outside Circuit ,
VFB = 0V force drive on
VFB = 0V force drive on
VFB =12V force drive off
Peak Current
No Outside Circuit ,
VFB = 0V force drive on
No Outside Circuit ,
VFB = 12V force drive off
VIN = 22V
VFB = 12V force drive off
Standby Quiescent Current
ISTBY
ON/OFF Pin=5V,VIN = 22V
ON/OFF Pin Logic Input
Threshold Voltage
ON/OFF Pin Input Current
ON/OFF Pin Logic Input
Current
Thermal Resistance
Thermal Resistance with
Copper Area of Approximately
3 in2
VIL
VIH
IL
Low (Regulator ON)
High (Regulator OFF)
VLOGIC=0.5V(ON)
IH
VLOGIC=2.5V(OFF)
Output=0
2/9
Test Conditions
VFB = 1.3V
(Adjustable Version Only)
IL
Min.
Typ.
-10
127
110
150
10
30
1.25
Max.
-50
-100
173
173
Unit
50
kHz
1.4
1.5
100
0
3.6
6.9
3.4
7.5
5
70
2.0
1.3
nA
kHz
V
%
A
-50
µA
-30
10
200
250
0.6
mA
mA
µA
V
-5
-15
θJC
SOP8L
Junction to Case
15
θJA
SOP8L
Junction to
Ambient
70
2007-3-27
µA
℃/W
150KHZ,2A PWM BUCK DC/DC CONVERTER
FSP3125
„ ELECTRICAL CHARACTERISTICS(CONTINUED)
(Unless otherwise specified, VIN=12V for 3.3V, 5V and adjustable version and VIN=18V for the 12V version. ILOAD =
0.5A)
Parameter
Output
Feedback
Symbol
VFB
FSP3125-ADJ
Test Conditions
4.5V ≤VIN ≤22V
0.2A ≤ILOAD ≤2A
VOUT Programmed for 3V
Min.
1.193
1.18
Efficiency
η
VIN =12V, ILOAD= 2A
75
Output
Feedback
VOUT
4.5V ≤VIN ≤22V
0.2A ≤ILOAD ≤2A
3.168
3.135
η
VIN =12V, ILOAD= 2A
78
7V ≤VIN ≤22V
0.2A ≤ILOAD ≤2A
VIN =12V, ILOAD= 2A
4.8
4.75
83
15V ≤VIN ≤22V
0.2A ≤ILOAD ≤2A
11.52
FSP3125-3.3V
Efficiency
Output
Feedback
Efficiency
Output
Feedback
FSP3125-5.0V
VOUT
η
FSP3125-12V
VOUT
Typ.
1.23
Max.
1.267
1.28
3/9
V
%
3.3
3.432
3.465
V
%
5.2
5.25
5
12
12.48
11.4
12.6
Efficiency
η
VIN =15V, ILOAD= 2A
90
Specifications with boldface are for full operating temperature range, the other type are for TJ=25°C
„
Unit
FUNCTIONAL BLOCK DIAGRAM
2007-3-27
V
%
V
%
150KHZ,2A PWM BUCK DC/DC CONVERTER
FSP3125
„ Function Description
Pin Description
+VIN
This is the positive input supply for the IC switching regulator. A suitable input bypass capacitor must be presented at
this pin to minimize voltage transients and to supply the switching currents needed by the regulator.
Ground
Circuit Ground
Output
Internal Switch. The voltage at this pin switches between (+VIN-VSAT) and approximately -0.5V, with a duty cycle of
approximately VOUT/VIN. To minimize coupling to sensitive circuitry, the PC board copper area connected to this pin
should be minimized.
Feedback
Sense the regulated output voltage to complete the feedback loop.
SD
Allows the switching regulator circuit to be shutdown using logic level signals thus dropping the total input supply
current to approximately 150uA. Pulling this pin below a threshold voltage of approximately 1.3V turns the regulator
on, and pulling this pin above 1.3V (up to a maximum of 18V) shuts the regulator down. If this shutdown feature is not
needed, the SD pin can be wired to the ground pin.
Thermal Considerations
The SOP8L package needs a heat sink under most conditions. The size of the heatsink depends on the input voltage,
the output voltage, the load current and the ambient temperature. The FSP3125 junction temperature rises above
ambient temperature for a 2A load and different input and output voltages. The data for these curves was taken with
the FSP3125(SOP8L package) operating as a buck-switching regulator in an ambient temperature 25℃ (still air).
These temperature increments are all approximate and are affected by many factors. Higher ambient temperatures
requires more heat sinker.
For the best thermal performance, wide copper traces and generous amounts of printed circuit board copper should
be used in the board layout. (One exception is the output (switch) pin, which should not have large areas of copper.)
Large areas of copper provide the best transfer of heat (lower thermal resistance) to the surrounding air, and moving
air lowers the thermal resistance even further.
Package thermal resistance and junction temperature increments are all approximate. The increments are affected by
a lot of factors. Some of these factors include board size, shape, thickness, position, location, and even board
temperature. Other factors are, trace width, total printed circuit copper area, copper thickness, single or double-sided,
multi-layer board and the amount of solder on the board.
The effectiveness of the PC board to dissipate heat also depends on the size, quantity and spacing of other
components on the board, as well as whether the surrounding air is still or moving. Furthermore, some of these
components such as the catch diode will add heat to the PC board and the heat can vary as the input voltage
changes. For the inductor, depending on the physical size, type of core material and the DC resistance, it could either
act as a heat sink taking heat away from the board, or it could add heat to the board.
4/9
2007-3-27
150KHZ,2A PWM BUCK DC/DC CONVERTER
FSP3125
„ Typical Application Circuit
(1) Fixed Output Version Circuit
(2) Adjustable Version Circuit
5/9
2007-3-27
150KHZ,2A PWM BUCK DC/DC CONVERTER
FSP3125
„ TYPICAL CHARACTERISTICS
6/9
2007-3-27
150KHZ,2A PWM BUCK DC/DC CONVERTER
FSP3125
„ TYPICAL CHARACTERISTICS(CONTINUED)
7/9
2007-3-27
150KHZ,2A PWM BUCK DC/DC CONVERTER
FSP3125
„
ORDER INFORMATION
FSP3125XXXX
Package:
S: SOP8L
„
Temperature Grade:
Output Voltage: Packing:
Blank: Tube or Bulk E: -40~125℃
Blank: ADJ
A: Tape & Reel
33: 3.3V
50: 5.0V
12: 12V
MARKING INFORMATION
Logo
3125-VV
YYWWXX
Part number:
3125-ADJ: ADJ
3125-33: 3.3V
3125-50: 5.0V
3125-12: 12V
Internal code
Date code:
YY: Year (01=2001)
WW: Nth week (01~52)
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2007-3-27
150KHZ,2A PWM BUCK DC/DC CONVERTER
FSP3125
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
9/9
Dimensions In Millimeters
Nom.
Max.
1.60
1.75
0.25
1.45
1.55
0.41
0.51
0.20
0.25
4.90
5.00
3.90
4.00
1.27TYP.
5.80
5.99
6.30
0.38
0.71
1.27
0ο
8ο
Min.
1.35
0.10
1.35
0.33
0.19
4.80
3.80
Dimensions In Inches
Min.
Nom.
0.053
0.063
0..004
0.053
0.057
0.013
0.016
0.0075
0.008
0.192
0.196
0.148
0.154
0.050TYP.
0.228
0.236
0.015
0.028
0ο
2007-3-27
Max.
0.069
0.010
0.061
0.020
0.010
0.200
0.160
0.248
0.050
8ο
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