1a, 0.25v feedback voltage step-down switching regulators for led

Advanced Power
Electronics Corp.
Preliminary
APE1831/A
1A, 0.25V FEEDBACK VOLTAGE STEP-DOWN
SWITCHING REGULATORS FOR LED DRIVER
GENERAL DESCRIPTION
APE1831/A consists of step-down switching regulator with PWM control. These
devise include a reference voltage source, oscillation circuit, error amplifier, internal PMOS
and etc.
APE1831/A provides low-ripple power, high efficiency, and excellent transient
characteristics. The PWM control circuit is able to the duty ratio linearly from 0 up to 100%.
An enable function, an over current protect function and short circuit protect function are
built inside, and when OCP or SCP happens, the operation frequency will be reduced. 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 SO-8 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.
FEATURES
-
Input Voltage：4.5V to 23V
Output Voltage：0.25V to VCC
-
LED Backlight and High Power LED Application
Duty Ratio：0% to 100% PWM control
Oscillation Frequency：
APE1831: 330KHz typ.
APE1831A: 500KHz typ.
-
Enable/Disable Function.
Current Limit (CL), Thermal Shutdown and Short Circuit Protections (SCP).
Built-in Internal SW P-channel MOS.
No Output Capacitor is Stable.
SO-8 Pb-Free Package.
Data and specifications subject to change without notice
1
20110309pre
Advanced Power
Electronics Corp.
APE1831/A
BLOCK DIAGRAM
SW
Oscillator
Circuit
Vcc
Reference Voltage
+
PWM Switched
Control Circuit
Thermal
Shutdown
VEN
-
FB
Vss
Current
Limit
Comp
EN
PIN ASSIGNMET
The package of APE1831/A is SO-8; the pin assignment is given by:
Name
Description
FB
( Top View )
FB
1
8
Vss
EN
2
7
Vss
Comp
3
6
SW
Vcc
4
5
SW
SO-8
Feedback pin
Power-off pin
H：normal operation(Step-down)
EN
L：Step-down operation stopped
(All circuits deactivated)
Comp Compensation pin
VCC
SW
VSS
IC power supply pin
Switch
pin.
Connect
inductor/diode here.
GND pin
external
ORDER/MARKING INFORMATION
Order Information
Top Marking
Part Number
APE1831X X
Package Type
Frequecny
Blank : 330KHz
M : SO-8
A : 500KHz
1831X
YWWSSS
Frequency Option Code
ID code: internal
WW: 01~52
Year: A = 20X0
1 = 20X1
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Electronics Corp.
APE1831/A
ABSOLUTE MAXIMUM RATINGS (at TA=25°C)
Characteristics
VCC Pin Voltage
Feedback Pin Voltage
ON/OFF Pin Voltage
Switch Pin Voltage
Power Dissipation
Storage Temperature Range
Operating Temperature Range
Operating Supply Voltage
Thermal Resistance from Junction to Case
Thermal Resistance from Junction to Ambient
Symbol
Rating
Unit
VCC
VSS - 0.3 to VSS + 25
V
VFB
VSS - 0.3 to VCC
V
VEN
VSS - 0.3 to VCC + 0.3
V
VSW
VSS - 0.3 to VCC + 0.3
V
PD
Internally limited
mW
TST
-40 to +150
°C
TOP
-40 to +125
°C
VOP
+4.5 to +23
V
θJC
25
°C/W
θJA
70
°C/W
Note : θJA is measured with the PCB copper area(need connect to SW pins) of approximately 1 in2(Multi-layer).
ELECTRICAL CHARACTERISTICS
(VIN = 12V, TA=25°C, unless otherwise specified)
Characteristics
Feedback Voltage
Symbol
VFB
Conditions
Min Typ Max Units
IOUT=0.2A
0.24 0.25 0.26 V
VFB=1.2V force driver
3 5 mA
Quiescent Current
ICCQ
off
Feedback Bias Current
IFB
IOUT=0.1A
- 0.1 0.5 uA
Shutdown Supply Current
ISD
VEN =0V
- 2 10 uA
Switch Current
ISW
1.3 A
△VOUT/VOUT VCC=5V~23V,
- 1 2
Line Regulation
%
IOUT=0.2A
Load Regulation
△VOUT/VOUT IOUT = 0.1 to 1A
- 0.2 0.5 %
APE1831
260 330 400 KHz
Oscillation Frequency
FOSC
APE1831A
400 500 600 KHz
EN Pin Logic Input Threshold
VSH
High (regulator ON)
2.0 V
Voltage
VSL
Low (regulator OFF)
- 0.8
ISH
VEN=2.5V (ON)
- 20 - uA
EN Pin Input Current
ISL
VEN=0.3V (OFF)
- -10 - uA
VCC=5V, VFB=0V
- 160 220
Internal MOSFET RDSON
RDSON
mΩ
VCC=12V, VFB=0V
- 120 180
IOUT = 0.5A - 91 Efficiency
EFFI
VOUT = 5V
%
IOUT = 1A
- 91 Thermal Shutdown Temp
TSD
- 140 - °C
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Electronics Corp.
APE1831/A
APPLICATION CIRCUIT
A. 1W/3W LED*1 for DC Input
U1
VCC
R1
100K
FB
VSS
EN
COMP
VSS
SW
VCC
VOUT
L1
SW
APE1831/A
D6
C3
0.1u
C2
22u
C4
LED
1N4148 R4 4.7K
Option
R5
100K
1u
D7
22uH
(10uH for
APE1831A)
D5
C1
B240A
4.7u
R2
0.75R/0.33R
1W/3W
B. 1W/3W LED*1 for AC Input
(1) No Output Capacitor
U1
AC
12V IN
AC D4
AC D3
VOUT
L1
D2
LED
SW
R5
C3
C2
APE1831A
VSS
SW
APE1831/A
AC D1
APE1831
VSS
VCC
AC D2
Part No.
FB
EN
COMP
0.1u
ILED
R2
R2
D5
C5
100nF
B240A
C2
R5
350mA
0.715Ω
87.5mW
100uF
0.22K
750mA
0.333Ω
189mW
220uF
0.47K
350mA
0.715Ω
87.5mW
100uF
0.22K
750mA
0.333Ω
189mW
220uF
0.47K
L1
68uH
47uH
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Electronics Corp.
APE1831/A
(2) Add 4.7uF Output Capacitor
U1
AC
12V IN
AC D4
AC D3
AC D2
VSS
EN
VSS
COMP
SW
VCC
SW
VOUT
L1
D2
LED
APE1831/A
R5
100R
AC D1
FB
C1
4.7u
C4
C3
C2
Part No.
APE1831
APE1831A
0.1u
ILED
C5
100n
R2
D5
B240A
R2
C2
350mA
0.715Ω
87.5mW
100uF
750mA
0.333Ω
189mW
220uF
350mA
0.715Ω
87.5mW
100uF
750mA
0.333Ω
189mW
220uF
C4
L1
10nF
33uH
3.3nF
22uH
FUNCTION DESCRIPTIONS
PWM Control
The APE1831/A consists of DC/DC converters that employ a pulse-width modulation
(PWM) system. In converters of the APE1831/A, 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.
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APE1831/A
Setting the ILED Current
Application circuit item shows the basic application circuit with APE1831/A adjustable
output version. The external resistor sets the LED output current according to the following
equation:
I
LED
⎛ 0.25V ⎞
=⎜
⎟
⎝ R2 ⎠
Table 1 Resistor select for LED output current setting
ILED
R2
350mA
0.715Ω
87.5mW
750mA
0.333Ω
189mW
RDS (ON) Current Limiting
The current limit threshold is setting by the internal circuit.
Compensation
Please refer the table of application circuit. For DC input, the option circuit for
compensation is connecting R4 and a 4148 diode to VOUT. In order to protect short circuit
and thermal shutdown release for LED.
PCB layout guide
If you need low Tc and Tj or large PD (Power Dissipation), the dual SW pins (5&6) on
the SO-8 package are internally connected to die pad, The PCB layout should allow for
maximum possible copper area at the SW pins of the APE1831/A.
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APE1831/A
TYPICAL CHARACTERISTICS
Temperature vs. Iccq
(Vcc=12V)
10
Shutdown Current (uA)
4
3.6
Iccq (mA)
Temperature vs. Shutdown Current
(Vcc=12V)
3.2
2.8
2.4
8
6
4
2
0
2
-40
-25
0
25
50
85
105
-40
125
-25
0
50
85
105
125
Temperature (℃ )
Temperature (℃)
Temperature vs. VFB
(Vcc=12V Iout=300mA Rcomp=100K)
Temperature vs. Frequency
(Vcc=12V Vout=3.3V)
0.26
600
0.256
500
Frequency (KHz)
VFB (V)
25
0.252
0.248
0.244
APE1831A
400
300
APE1831
200
100
0
0.24
-40
-25
0
25
50
85
105
-40
125
-25
25
50
85
105
125
Temperature (℃ )
Temperature (℃ )
Line Regulation
(Vout=3.3V)
0.257
0
Iout vs. EFFI
(Vcc=12V)
100
VOUT=5V
90
0.255
0.253
VOUT=3.3V
70
EFFI (%)
VFB (V)
80
0.251
0.249
60
50
40
30
0.247
20
10
0.245
4.5V
5V
12V
15V
Vcc
20V
22V
23V
0
0
0.2
0.4
0.6
0.8
1
Iout (A)
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Advanced Power
Electronics Corp.
APE1831/A
H
E
PACKAGE OUTLINES
θ
L
DETAIL A
b
D
e
Symbol
A
A1
A2
C
D
E
H
L
b
e
y
θ
y
A1
C
A
A2
7 (4X)
Dimensions in Millimeters
Min.
Nom.
Max.
1.35
1.60
1.75
0.10
0.25
1.30
1.45
1.50
0.19
0.20
0.25
4.70
4.90
5.10
3.70
3.90
4.10
5.79
5.99
6.20
0.38
0.71
1.27
0.33
0.41
0.51
1.27 TYP.
0.10
O
0
8O
DETAIL A
Dimensions in Inches
Min.
Nom.
Max.
0.053
0.063
0.069
0.040
0.100
0.051
0.057
0.059
0.0075
0.008
0.010
0.185
0.193
0.200
0.146
0.154
0.161
0.228
0.236
0.244
0.015
0.028
0.050
0.013
0.016
0.020
0.050 TYP.
0.004
O
0
8O