Eorex EP3102 150 khz, 2a asynchronous step-down converter Datasheet

eorex
(Preliminary)
EP3102
150 KHz, 2A Asynchronous Step-down Converter
Features
Description
• 3.3V, 5V, 12V and Adjustable Output Version
• Adjustable Version Output Voltage Range,
1.23V to 37V +4% Max over Line and Load
Condition
• Input Voltage Range up to 40V
• Output Load Current: 2A
• 150 KHz Fixed Frequency Internal Oscillator
• Voltage Mode Non-synchronous PWM Control
• Thermal-shutdown and Current-limit Protection
• ON/OFF Shutdown Control Input
• Low Power Standby Mode
• Built-in Switching Transistor on Chip
• SOP-8L package
The EP3102 is a monolithic integrated circuit that
provide all the active functions for a step-down
switching regulator, capable of driving a 2A load
without
additional
transistor
component.
Requiring a minimum number of external
component, the board space can be saved easily.
The external shutdown function can be controlled
by TTL logic level and then come into standby
mode. The internal compensation makes
feedback control have 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. The EP3102 operates at a
switching frequency of 150KHz thus allowing
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 package is available in a
standard 8-lead SOP8.
Applications
• Simple High-efficiency Step-down (Buck)
Regulator
• Efficient Pre-regulator for Linear Regulators
• On-card Switching Regulators
• Positive to Negative Converter
• Battery Charger
Typical Application
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EP3102
Pin Assignment
Ordering Information
EP3102 - X X X
Buck Regulator
Package
VOUT
Packing
S : SOP-8L
Blank: Adj
33 = 3.3V
50 = 5.0V
12 = 12V
R: Taping & Reel
B: Bag
Pin Description
Pin
Name
Function
1
VIN
This is the positive input supply for the IC switching regulator. A suitable
input bypass capacitor must be present at this pin to minimize voltage
transients and to supply the switching currents needed by the regulator.
2
SW
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 kept a minimum.
3
FB
Senses the regulated output voltage to complete the feedback loop.
4
EN
Low enable. 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 40V) shuts the regulator down. If this
shutdown feature is not needed, the EN pin can be wired to the ground
pin or it can be left open, in either case the regulator will be in the ON
condition.
5~8
GND
Circuit ground.
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EP3102
Absolute Maximum Rating (Note 1)
Symbol
VIN
Item
Input Supply Voltage
V EN
VFB
VOUT
VOP
PD
TOP
TSTG
EN Pin Input Voltage
Feedback Pin Voltage
Output Voltage to Ground
Operating Voltage
Power Dissipation
Operating Temperature Range
Storage Temperature Range
Rating
Units
+45
V
-0.3 ~ +25
V
-0.3 ~ +25
-1
+4.5 ~+25
Internally Limited
-40 ~ +125
-65 ~ +150
V
V
V
W
°C
°C
Electrical Characteristics (All Output Voltage Versions) (Note 2)
Unless otherwise specified, VIN=12V for 3.3V, 5V, adjustable version and VIN=24V for the 12V version.
ILOAD=0.2A
Symbol
IFB
Parameter
Feedback Bias Current
FOSC
Oscillator Frequency
FSCP
Oscillator Frequency of Short
Circuit Protect
VSAT
Saturation Voltage
DC
ICL
IL
Max. Duty Cycle (ON)
Min. Duty Cycle (OFF)
Current Limit
Output=0
Output=-1
IQ
ISTBY
Output Leakage
Current
Conditions
Min.
VFB=1.3V
(Adjustable version only)
127
110
When current limit occurred
and VFB<0.55V
IOUT=1.5A
no outside circuit VFB=0V
force driver on
VFB=0V force driver on
VFB=12V force driver off
Peak Current
no outside circuit VFB=0V
force driver on
Typ.
Max.
Units
-10
-50
-100
nA
150
173
173
KHz
30
70
KHz
1.25
1.4
1.5
100
0
2.4
2.8
No outside circuit VFB=12V
fore driver off
%
3.3
3.6
-200
VIN=24V
-5
Quiescent Current
VFB=12V force driver off
5
Standby Quiescent Current
EN pin=5V
VIN=24V
Low (regulator ON)
70
V
A
µA
mA
10
150
200
0.6
mA
-0.01
µA
-1
µA
µA
VIL
VIH
EN Pin Logic Input Threshold
Voltage
High (regulator OFF)
IH
EN Pin Logic Input Current
VLOGIC=2.5V (OFF)
IL
EN Pin Input Current
VLOGIC=0.5V (ON)
-0.1
TS
Over Temperature Shutdown
Threshold
TJ increasing
TJ decreasing
175
150
°C
°C
θJC
Thermal Resistance
SOP-8L
Junction to Case
15
°C/W
θJA
Thermal Resistance with
Copper Area of Approximately
3in2
SOP-8L
Junction to
Ambient
70
°C/W
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EP3102
Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired.
Note 2:100% production test at +25°C. Specifications over the temperature range are guaranteed by
design and characterization.
Electrical Characteristics (Continued)
Symbol
VFB
η
VOUT
η
VOUT
η
VOUT
η
Parameter
Output Feedback
EP3102-ADJ
Conditions
5V<VIN<40V
0.2A<ILOAD<2A
VOUT programmed for 3V
Typ.
Limit
Units
1.235
1.193/1.18
1.267/1.28
V
VMIN
VMAX
Efficiency
VIN=12V, ILOAD=2A
75
Output Voltage
5.5V<VIN<40V
0.2A<ILOAD<2A
3.3
Efficiency
VIN=12V, ILOAD=2A
75
Output Voltage
8V<VIN<40V
0.2A<ILOAD<2A
5
Efficiency
VIN=12V, ILOAD=2A
80
Output Voltage
15V<VIN<40V
0.2A<ILOAD<2A
12
VIN=15V, ILOAD=2A
90
Efficiency
EP3102-3.3V
EP3102-5V
EP3102-12V
%
3.168/3.135
3.432/3.465
V
VMIN
VMAX
%
4.8/4.75
5.2/5.25
V
VMIN
VMAX
%
11.52/11.4
12.48/12.6
V
VMIN
VMAX
%
P.S. Specifications with boldface type are for full operating temperature range, the other type are for
TJ=25ºC.
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Threshold Voltage (V)
Supply Voltage (V)
Saturation Voltage (V)
Efficiency (%)
Output Voltage (V)
Output Voltage (V)
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EP3102
Typical Performance Characteristics
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EP3102
Typical Performance Characteristics (Continued)
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EP3102
Functional Block Diagram
Applications Information
(1) Fixed Type Circuit
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EP3102
Applications Information (Continued)
(2) Adjustable Type Circuit
R2
R1
3
FB
1
12V
DC Input
CIN
330uF
+
VIN
EP3102
SW
L1
33uH
2
D1
Schottky Diode
EN GND GND GND GND
4
5
6
7
8
⎛
⎝
VOUT= VFB × ⎜1 +
2.5V/2A
Output Load
Inductor
+
COUT
330uF
R1 ⎞
⎟
R2 ⎠
VFB=1.23V
R2=1K ~ 3K
(3) Delay Start Circuit
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EP3102
Thermal Considerations
The SOP-8 package needs a heat sink under most conditions. The size of the heat-sink depends on the
input voltage, the output voltage, the load current and the ambient temperature. The EP3102 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 EP3102 operating as a buck switching regulator in an
ambient temperature of 25°C (still air). These temperature increments are all approximate and are
affected by many factors. Some of these factors include board size, shape, thickness, position, location,
and even board temperature. Other factors are traced width, total printed circuit copper area, copper
thickness, single or double-sided, multi-layer board and amount of solder on the board. Higher ambient
temperatures require more heat sinking.
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 out (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.
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 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.
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EP3102
Package Description
SOP-8L
DIM
MILLIMETERS
INCHES
MIN.
NOM.
MAX.
MIN.
NOM.
MAX.
A
1.40
1.60
1.75
0.055
0.063
0.069
A1
0.10
−
0.25
0.040
−
0.100
A2
1.30
1.45
1.50
0.051
0.057
0.059
B
0.33
0.41
0.51
0.013
0.016
0.020
C
0.19
0.20
0.25
0.0075
0.008
0.010
D
4.80
4.85
5.05
0.189
0.191
0.199
E
3.80
3.91
4.00
0.150
0.154
0.157
e
−
1.27
−
−
0.050
−
H
5.79
5.99
6.20
0.228
0.236
0.244
L
0.38
0.71
1.27
0.015
0.028
0.050
y
−
−
0.10
−
−
0.004
θ
0°
−
8°
0°
−
8°
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