SG2540M [MICROSEMI]
OFF-LINE START-UP CONTROLLER; OFF- LINE START -UP控制器
| 型号： | SG2540M |
| 厂家： | 
Microsemi |
| 描述： | OFF-LINE START-UP CONTROLLER |
| 文件： | 总6页 (文件大小：82K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
SG1540/SG2540/SG3540
OFF-LINE START-UP CONTROLLER
DESCRIPTION
FEATURES
The SG1540 is an integrated circuit designed to efficiently provide
start-up power from a high-voltage DC bus to a PWM control circuit
in a switching power supply. When used on the primary side, it
reduces start-up current to less than 1mA and allows any standard
PWM control circuit to be used as a primary-side controller. When
used to power a controller on the secondary side, it efficiently
eliminates the need for a heavy 50/60Hz line transformer with its
associated low frequency magnetic fields.
• Useable with primary and secondary side PWM
controllers
• Micropower comparator / switch
- Internal 2.5V bandgap reference
- 50mA power switch
• Squarewave oscillator
- 500Hz to 200KHz operation
- 200mA totem pole outputs
• Eliminates bulky, expensive 50/60 Hz transformer
• Minimizes high voltage bleeder current
• Programmable start-up voltage and hysteresis
• Internal and programmable overvoltage crowbar
latch
The circuit consists of three sections: a micropower bandgap
comparator/power switch referenced to 2.5 volts which isolates the
start-up capacitor from its load; a high frequency square-wave
oscillator with 200mA totem-pole output for driving an isolation
transformer; and a second bandgap comparator with latching
crowbar to protect against overvoltage faults while starting or
running.
• Available in 8 pin DIP, 10 pin flat pack, and 16 pin
widebody SOIC
HIGH RELIABILITY FEATURES - SG1540
The SG1540 is specified for operation over the full military ambient
temperature range of -55°C to 125°C. The SG2540 is character-
ized for the industrial range of -25°C to 85°C, and the SG3540 is
designed for the commercial range of 0°C to 70°C.
♦ Available to MIL-STD - 883
♦ LMI level "S" processing available
BLOCK DIAGRAM
4/90 Rev 1.1 2/94
LINFINITY Microelectronics Inc.
Copyright 1994
11861 Western Avenue ∞ Garden Grove, CA 92841
1
(714) 898-8121 ∞ FAX: (714) 893-2570
SG1540/SG2540/SG3540
ABSOLUTE MAXIMUM RATINGS (Note 1)
Overvoltage Crowbar Energy (½CV²) ................................. 8mJ
Operating Junction Temperature
Hermetic (Y Package) ................................................ 150°C
Plastic (M, DW Packages) .......................................... 150°C
Storage Temperature Range ............................ -65°C to 150°C
Lead Temperature (Soldering, 10 Seconds) .................. 300°C
Supply Voltage (+V ) ........................................................ +37V
DC Output Current,INContinuous (VOUT)........................... 100mA
AC Output Current, Continuous ..................................... 200mA
Analog Inputs (Start and Overvoltage) ................. -0.3V to 6.0V
Analog Input Currents (V>8V).......................................... 10mA
Overvoltage Crowbar Current, Continuous ..................... 50mA
Note 1. Values beyond which damage may occur.
THERMAL DATA
Y Package:
Note A. Junction Temperature Calculation: TJ = TA + (PD x θJA).
Note B. The above numbers for θJC are maximums for the limiting
thermal resistance of the package in a standard mount-
ing configuration. The θJA numbers are meant to be
guidelines for the thermal performance of the device/pc-
board system. All of the above assume no ambient
airflow.
Thermal Resistance-Junction to Case, θJC .................. 50°C/W
Thermal Resistance-Junction to Ambient, θJA ............ 130°C/W
M Package:
Thermal Resistance-Junction to Case, θJC .................. 60°C/W
Thermal Resistance-Junction to Ambient, θJA ............. 95°C/W
DW Package:
Thermal Resistance-Junction to Case, θJC .................. 40°C/W
Thermal Resistance-Junction to Ambient, θJA ............. 95°C/W
RECOMMENDED OPERATING CONDITIONS (Note 2)
Supply Voltage Range ............................................... 7V to 35V
DC Output Current, Continuous ................................ 0 to 50mA
AC Output Current, Continuous ............................. 0 to 100 mA
Oscillator Frequency Range ........................... 1KHz to 400KHz
Timing Resistor Range ...................................... 2KΩ to 150KΩ
Timing Capacitor Range ........................................ 1nF to 20µF
Operating Ambient Temperature Range
SG1540 ...........................................................-55°C to 125°C
SG2540 .............................................................-25°C to 85°C
SG3540 ................................................................ 0°C to 70°C
Note 2. Range over which the device is functional.
ELECTRICAL CHARACTERISTICS
(Unless otherwise specified, these specifications apply over the operating ambient temperatures for SG1540 with -55°C ≤ TA ≤ 125°C, SG2540 with
-25°C ≤ TA ≤ 85°C, SG3540 with 0°C ≤ TA ≤ 70°C, and +VIN = 15V. A 0.1µF high frequency bypass capacitor is recommended on VIN. Low duty cycle
testing techniques are used which maintains junction and case temperatures equal to the ambient temperature.)
SG1540/2540/3540
Parameter
Start-up Section
Test Conditions
Units
Min.
Typ. Max.
Start Current ICC
Operating Current
VSTART = 0 to 2.37V
VTIMING = +V ; VOUT Open
0.2
0.3
3
0.4
0.6
6
mA
mA
mA
V
IN
F
OSC = 50KHz, VOUT and AC OUT Open
Start Threshold
2.37 2.50 2.63
Start Bias Current
Start Clamp Voltage
Hysteresis ON Voltage
VPIN 1 = 0 to 5V
PIN 1 = 1mA
IPIN 4 = 100µA
0.1
7
0.1
1
8
0.2
µA
V
V
I
6
DC Output Section
ISOURCE = 10mA
VOUT Voltage
12.5 13.5
12.0 13.0
V
V
ISOURCE = 50mA
Short Circuit Current
VOUT = 0V
50
100 225
mA
4/90 Rev 1.1 2/94
LINFINITY Microelectronics Inc.
Copyright 1994
11861 Western Avenue ∞ Garden Grove, CA 92841
2
(714) 898-8121 ∞ FAX: (714) 893-2570
SG1540/SG2540/SG3540
ELECTRICAL CHARACTERISTICS (continued)
SG1540/2540/3540
Units
Parameter
Test Conditions
Min. Typ. Max.
Oscillator Section (Note 3)
Initial Accuracy
Voltage Stability
Temperature Stability (Note 4)
Oscillator Minimum Frequency
Oscillator Maximum Frequency
TJ = 25°C
+VIN = 12 to 18V
46
50
5
2
54
12
5
KHz
%
%
KHz
KHz
RT = 17.8K, CT = .068µF
RT = 1.5K, CT = 470pF
1
400
AC Output Section
HIGH Output Voltage
ISOURCE = 20mA
12.5 13.5
12.0 13.0
0.2
V
V
V
I
SOURCE = 100mA
ISINK = 20mA
SINK = 100mA
LOW Output Voltage
0.3
2.0
55
0.6
0.2
I
1.2
V
Squarewave Duty Cycle
AC Output Risetime
AC Output Falltime
45
50
0.3
0.1
%
µS
µS
CL = 1000pF
CL = 1000pF
Overvoltage Crowbar Section
Overvoltage Threshold
Overvoltage Bias Current
Overvoltage Clamp Voltage
+VIN Overvoltage Threshold
SCR ON Voltage
2.37 2.50 2.63
V
µA
V
V
V
0.1
1
VO.V. = 0 to 2.37V
IO.V. = 1mA
6
7
8
37
42
9
44
12
IVIN = 35mA
SCR Holding Current
VO.V. = 0
0.15 0.35 0.55
mA
Note 3. FOSC = 50KHz, RT = 3.48K C = 4.7nF unless otherwise specified.
Note 4. These parameters, althoughTguaranteed, are not tested in production.
CHARACTERISTIC CURVES
FIGURE 1 - SATURATION VOLTAGE (DC OUT PIN) VS. OUTPUT CURRENT
FIGURE 2 - OSCILLATOR FREQUENCY VS. RT AND CT
4/90 Rev 1.1 2/94
LINFINITY Microelectronics Inc.
Copyright 1994
11861 Western Avenue ∞ Garden Grove, CA 92841
3
(714) 898-8121 ∞ FAX: (714) 893-2570
SG1540/SG2540/SG3540
APPLICATION INFORMATION
FIGURE 3 - EFFICIENT PRIMARY SIDE START-UP
PRIMARY SIDE START-UP
When the design goal is efficient start-up for a control PWM referenced to the primary side of the power transformer, the configuration
in Figure 3 is recommended. An energy storage capacitor CSTART is trickle-charged from the 300-400 Volt DC bus by resistor RSTART
The value of RSTART is chosen to provide a constant 1mA charging current, allowing the use of a ½ watt resistor. As the voltage on
START ramps up from zero, the only load current is the standby current of the SG1540 and that of the divider network R1-R3. (Connecting
.
C
the TIMING pin to +VIN disables the internal power oscillator and forces the circuitry into a micropower standby model. Since the input
bias current at the START pin is 1µA maximum, a divider current of 100µA is adequate).
When the voltage at the START pin reaches +2.5 Volts, the hysteresis transistor turns off, overdriving the START pin. The VOUT pin
is switched to the HIGH state, providing power to the PWM control circuit. As energy flows out of the START capacitor, its voltage
decays; but it remains connected to the PWM circuit until the dropout voltage is reached (VSTART - VHYSTERESIS). The bootstrap winding
on the power transformer and rectifier diode D5 prevent this from happening. As the PWM control circuit becomes active, the power
transistor begins to switch, providing operating current to the PWM circuit through the SG1540.
RESISTOR CALCULATIONS
Given that VSTART and VDROPOUT have been chosen, and that the divider current at start-up is 100µA, then the values for R1 through R3
are calculated as follows:
VSTART - 2.5
1. For simplification, let X =
2. Then,R1 = 2.5 x 104 * X
R2 = R1/Y
[1]
[2]
2.5
VDROPOUT -2.5
2.5
R1 * R2
X * R2 - R1
and Y =
and R3 =
[3]
DESIGN EXAMPLE
Suppose we have a power MOSFET device, and so want to start at +18 volts and drop out at +12 volts.
Then
X = 6.20
and Y = 3.80
Therefore
R1 = 2.5 x 104 * 6.2 = 155K
R2 = 1.5 x 105/3.8 = 39.5K
(Choose 150K)
(Choose 39K)
1.5 x 105 * 3.9 x 104
R3 =
= 63.7K
(Choose 62K)
6.2 * 3.9 x 104 - 1.5 x 105
4/90 Rev 1.1 2/94
LINFINITY Microelectronics Inc.
Copyright 1994
11861 Western Avenue ∞ Garden Grove, CA 92841
4
(714) 898-8121 ∞ FAX: (714) 893-2570
SG1540/SG2540/SG3540
APPLICATIONS INFORMATION (continued)
The voltage waveform at +VIN is shown in Figure 4 with these resistor values and with CSTART = 3µF. Notice that two tries are required
before the +15 volt bootstrap winding becomes active.
FIGURE 4 - STARTUP VOLTAGE WAVEFORM
FIGURE 5 - SECONDARY-SIDE START-UP WITHOUT A LINE TRANSFORMER
4/90 Rev 1.1 2/94
LINFINITY Microelectronics Inc.
Copyright 1994
11861 Western Avenue ∞ Garden Grove, CA 92841
5
(714) 898-8121 ∞ FAX: (714) 893-2570
SG1540/SG2540/SG3540
CONNECTION DIAGRAMS & ORDERING INFORMATION (See Notes Below)
Ambient
Temperature Range
Package
Part No.
Connection Diagram
8-PIN CERAMIC DIP
Y - PACKAGE
SG1540Y/883B
SG1540Y
SG2540Y
-55°C to 125°C
-55°C to 125°C
-25°C to 85°C
0°C to 70°C
8
7
6
5
START
OVER VOLTAGE
HYSTERESIS
TIMING
1
2
3
4
DC OUT
+V
IN
SG3540Y
AC OUT
GROUND
8-PIN PLASTIC DIP
M - PACKAGE
SG2540M
SG3540M
-25°C to 85°C
0°C to 70°C
16-PIN WIDE BODY
PLASTIC S.O.I.C.
DW - PACKAGE
SG2540DW
SG3540DW
-25°C to 85°C
0°C to 70°C
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
START
N.C.
DC OUT
N.C.
+VIN
OVER VOLTAGE
N.C.
N.C.
HYSTERESIS
N.C.
AC OUT
N.C.
GROUND
TIMING
N.C.
N.C.
Notes: 1. Contact factory for JAN and DESC part availability.
2. All parts are viewed from the top.
4/90 Rev 1.1 2/94
LINFINITY Microelectronics Inc.
Copyright 1994
11861 Western Avenue ∞ Garden Grove, CA 92841
(714) 898-8121 FAX: (714) 893-2570
6
∞
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