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SR036/SR037 SR036
SR037 Inductorless, Dual Output Off-Line Regulators
Features
Accepts peak input voltages up to 700V Operates directly off of rectified 120V AC or 230V AC Integrated linear regulator Minimal power dissipation
General Description
The Supertex SR036 and SR037 are inductorless, dual output off-line controllers, providing up to 1.0W of output power. They do not require any transformers, inductors, or high voltage input capacitors. The input voltage, HV IN, is designed to operate from an unfiltered full wave rectified 120V or 230V AC line. It is designed to control an external N-channel MOSFET or IGBT. When HV IN is less than 45V, the external transistor is turned-on allowing it to charge an external capacitor connected to VSOURCE. An unregulated DC voltage will develop on V SOURCE. Once HVIN is above 45V, the transistor is turned off. The maximum gate voltage for the external transistor is 24V. The unregulated voltage is approximately 18V. The SR036 also provides a regulated 3.3V whereas the SR037 provides a regulated 5.0V. WARNING!!! Galvanic isolation is not provided. Dangerous voltages are present when connected to the AC line. It is the responsibility of the designer to assure adequate safeguards are in place to protect the end user from electrical shock.
No high voltage capacitors required Up to 1.0W output power
No transformers or inductors required
Applications
3.3V or 5.0V power supplies White goods Appliances
SMPS house keeping power supplies
Small off-line low voltage power supplies Lighting controls
SR03x Typical Application Circuit
ed nd e m om igns! ec tR o es N D ew rN Fo
~18V Unregulated
GN2470
1.0F
470F
Surge Protection
Gate
120VAC or 230VAC
HVIN
SR036 or SR037
VSOURCE VOUT
SR036: VOUT = 3.3V Regulated SR037: VOUT = 5.0V Regulated 1.0F
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B092005
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SR036/SR037
Ordering Information
VOUT 3.3V 5.0V Package Options MSOP-8 SR036MG* SR037MG* SO-8 w/ Heat Slug SR036SG SR037SG
* Product supplied on 2500 piece carrier tape reel.
Absolute Maximum Ratings*
VIN, High Voltage Input VOUT, Low Voltage Output Storage Temperature Soldering Temperature Power Dissipation, MSOP-8 Power Dissipation, SO-8 slug
* All voltages are referenced to GND. 1. When underside plate soldered to 2cm2 of exposed copper. *Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these conditions is not implied. Continuous operation of the device at the absolute rating level may affect device reliability. All voltages are referenced to device ground.
Pin Configuration
+700V
HVIN
1 2 3 4
8 7 6 5
Gate Source VOUT N/C
+6.0V -65C to +150C +300C 300mW 1.50W1
N/C N/C GND
MSOP-8 (top view)
HVIN N/C N/C GND
1 2 3 4
8 7 6 5
Gate Source VOUT N/C
SO-8 Slug Make no electrical connections to Backside Plate (top view)
Electrical Characteristics
(Over operating supply voltages unless otherwise specified, TA=0C to +125C)
Symbol HVIN VTH VGS VGATE VOUT VOUT Freq Input voltage HVIN voltage when Gate is pulled to ground Gate to source clamp voltage Gate to ground clamp voltage Regulated output voltage for the SO-8 with heat slug VOUT load regulation Input AC frequency 40 SR036 SR037 40 10 18 2.97 4.5 45 15 20 3.30 5.00 20 Parameter Min Typ Max 700 407 50 20 24 3.63 5.50 120 100 Units V V V V V mV Hz VSOURCE = 10V VSOURCE = 10V VSOURCE = 10V, ILoad = 0 to 50mA (1) IGS = 100A Conditions Peak transient voltage Peak rectified AC voltage
(1) Load current on the regulated output must not cause SR03 power dissipation to exceed max ratings. Worst case power dissipation is given by:
P VIN
2
+ (16V - VOUT ) x I OUT
185k
Where IOUT is the load on the regulated output
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SR036/SR037
Typical Performance Curves
Gate Clamp
25 60
HVIN (off)
20
50
40
Vgate (V)
HVIN (V)
-40 -10 20 50 80 110 140
15
30
10
20 5
10
0
0 -40 -10 20 50 80 110 140
Temperature (C) Regulator Output (SR037)
6 20 18 5 16 14
Temperature (C) Gate Voltage
VGate (V)
0 5 10 15 20 25
4
VOUT (V)
12 10 8
3
2
6 4 2
1
0
0 0 10 20 30 40 50 60 70 80
Source Voltage (V) HV Input Current
2100 125C 1800 5.00 25C -40C 4.95 4.90 4.85 4.80 600 4.75 4.70 4.65 0 50 100 150 200 250 300 350 400 0 10 5.05
HVIN (V) Load Regulation (SR037)
1500
1200
IIN (A)
900
VOUT (V)
Source=15V 25C
Source=8V 25C
300 0
20
30
40
50
HVIN (V)
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IOUT (mA)
3
SR036/SR037
Applications Information Functional Block Diagram Operating Principle
The SR03x operates by controlling the conduction angle of the external MOSFET or IGBT as shown in Figure 1. When the rectified AC voltage is below the VTH threshold, the pass transistor is turned on. The pass transistor is turned off when the rectified AC is above HVIN(off). Output voltage (Vunreg) decays during the periods when the switch is off and when the rectified AC is below the output voltage. The amount of decay is determined by the load and the value of C1. Since the switch only conducts with low voltages across it, power dissipation is minimized.
HVIN VREF
CM
Gate
Source
Reg
VOUT
GND
Switch ON
HVIN V TH VREG
not to scale
VUNREG
Figure 1: Typical Waveforms Power Dissipation
Power dissipation in the SR03 is from 2 sources. The first is due to the bias current (or overhead) required to operate the device. This may be calculated from PBIAS = VIN2 / 185ky where VIN is the input voltage in VRMS. The second source of power dissipation is the 3.3/5V linear regulator and may be calculated from PREG = (16V - VOUT) * IREG, where VOUT is 3.3V or 5V, and IREG is the load current on the 3.3/5V output. The total power dissipated by the SR03x is the sum of these two: PBIAS + PREG. (These equations are conservative - actual dissipation may be less.) To adequately dissipate the power, the underside plate of the SR03xSG should be soldered to at least 2cm2 of exposed copper area on the PCB. Power is also dissipated by the pass transistor. Power dissipated by the transistor will be (16V * ITOTAL) * (1/Eff -1) where ITOTAL is the sum of the load currents on the regulated and unregulated outputs and Eff is the converter efficiency (see Efficiency Graph next page). The transistor should be soldered to at least 5cm2 of exposed copper area on the PCB for heatsinking.
Transformers
4
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SR036/SR037
Using a MOSFET in place of an IGBT
VN2460 1.0F
Gate
~18V Unregulated
270F
Surge Protection
120VAC or 230VAC
HVIN
SR036 or SR037
VSOURCE VOUT
SR036: VOUT=3.3V Regulated SR037: VOUT=5.0V Regulated 1.0F
SRO3 Efficiency
SR03 Efficiency
50
VN2460, no EMI GN2470, no EMI
Efficiency (%)
40
30
VN2460, w/EMI
GN2470, w/EMI
20 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6
PUNREG (W)
Efficiency and EMI Test Circuit
120/230VAC 50/60Hz GN2470 P6KE 400CA EMI Suppressor RG 180k VIN GATE SOURCE VREG VREG CREG 1.0F CG 220pF 1.0F VUNREG 220F (VN2460) 470F (GN2470)
SR03x
GND
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SR03 Circuit using VN2460 (with EMI Suppression Circuit)
SR036/SR037
6
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SR03 Circuit using GN2470 (no EMI Suppressor)
120VAC/60Hz Limits per 47CFR15.107 for Class B devices. 50mA total load.
Hot Neutral
SR036/SR037
Average
Quasi-peak
208VAC/60Hz (230VAC/50Hz not available). Limits per CISPR 14-1 for household appliances. 25mA total load.
Hot Neutral
Average
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Quasi-peak
7
SR03 Circuit using GN2470 (no EMI Suppressor)
120VAC/60Hz Limits per 47CFR15.107 for Class B devices. 100mA total load.
Hot Neutral
SR036/SR037
Average
Quasi-peak
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Applications Information, continued
GN2470
1.0F
SR036/SR037
Fuse
VUNREG
220F
120VAC or 230VAC
Surge Protection
1K
Gate HVIN
Source VOUT
SR036 or SR037
GND
VREG 1.0F
ON/OFF
TN2106K1
Figure 2: Example Circuit with Enable Control
Figure 2 is an example circuit using the SR036 or SR037 along with a Supertex GN2470 IGBT to generate an unregulated voltage of approximately 18V and a regulated voltage of 3.3V for the SR036 or 5.0V for the SR037. The combined total output current is typically 50mA. The TN2106K1 in series with a 1Ky resistor can be added for applications requiring an enable control.
Fuse
Surge Protection
GN2470
1.0F
2N3904 220F 10K 1.0M Vz 5.6V
Vout1 = 5.0V 1.0F
120VAC or 230VAC
Gate HVIN
Source V OUT
SR036
GND
Vout 2 = 3.3V 1.0F
Figure 3: Generating Two Regulated Voltages
For applications requiring two regulated voltages, an inexpensive discrete linear regulator can be added to regulate the unregulated output as show in Figure 3. The discrete linear regulator consists of a Zener diode, a resistor and a bipolar transistor. The regulated voltage, Vout1, is determined by the Zener diode voltage minus the base-to-emitter voltage drop of 0.6V. Figure 3 uses a 5.6V Zener diode to obtain a 5.0V output. Different Zener diode voltages can be used to obtain different regulated output voltages.
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9
SR036/SR037
Applications Information, continued
Fuse GN2470 Unregulated Voltage
1.0F
Surge Protection
120VAC or 230VAC
220F
1N4001
Gate HVIN
Source VOUT
3.3V 1.0F
SR036
GND
Logic Control Circuit
12V Coil Relay VN2110K1
Figure 4: Driving 12V Relay Coils
The circuit shown in Figure 4 uses the SR036 to supply a regulated 3.3V for the logic control circuitry while the unregulated voltage is used to drive a 12V relay coil. The operating voltage for a 12V relay coil is typically very wide and can therefore operate directly from the unregulated line.
Fuse
Surge Protection
GN2470
Unregulated Voltage
1.0F
120VAC or 230VAC
220F
1N4001
Gate HVIN
Source VOUT
SR037
GND
5.0V 1.0F
Logic Control Circuit
1K 2N3904 100
5V Coil Relay
Figure 5: Driving 5V Relay Coils
The circuit shown in Figure 5 uses the SR037 to supply a regulated 5.0V for the logic control circuitry while the unregulated voltage is used to drive a 5.0V coil relay. To overcome the voltage variation of the unregulated line, a bipolar transistor is used to drive the coil with a constant current. The resistor value from the emitter to ground sets the desired coil current. For an arbitrary coil current of 40mA, the resistor value can be calculated as:
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B092005
SR036/SR037
Applications Information, continued
Fuse
GN2470 Unregulated Voltage
1.0F
Surge Protection
120VAC or 230VAC
220F
Vz 5.1V 5V Coil Relay
Gate HVIN
Source VOUT
SR037
GND
5.0V 1.0F
Logic Control Circuit
Figure 6: Driving 5V Relay Coils with Zener Diode Clamp
The circuit shown in Figure 6 uses the SR037 to supply a regulated 5.0V for the logic control circuitry. A 5.1V Zener diode is used in parallel with the 5.0V relay coil to ensure that the relay coil's maximum operating voltage is not exceeded. The Zener diode also acts as the catch diode when the coil is switched to the off state. An external series resistor is used to limit the amount of Zener current.
Fuse
GN2470
Unregulated Voltage
1.0F
Surge Protection
220F
120VAC or 230VAC
Gate HVIN
Source VOUT
SR036 or SR037
GND
VREG
1.0F
330 330
Figure 7: Driving LEDs from 120VAC
The circuit shown in Figure 7 uses the SR036 or SR037 to drive 12 high efficiency red LEDs from an AC line. The average LED current is approximately 20mA.
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11
SR036/SR037
Applications Information, continued
Vunreg = Vz + 14V = VLED + 8V
Fuse
GN2470
1.0F + 47F
R = Vunreg / 1.5mA
Vunreg +
Surge Protection
AC line
220pF
180K
EMI Filter (optional) R
VLED
ILED
Gate HVIN
Source +8V
Supertex SR037
GND
Figure 8: Precision current drive for LED String from AC Line
Features: 1. Precision Current Regulator 2. Zener Voltage Boost 3. PWM Dimming (optional) 4. EMI Filter (optional)
PWM Dimming (optional)
Constant Current Regulator
Iled = 2.5V / Rs < 40mA
The circuit uses the SR037or SR036 and GN2470 to drive a string of LEDs from AC power line. The LED current is regulated at up to 40mA. The LED string voltage can be up to AC line voltage (120V for 120Vac / 230V for 230VAC).
Vunreg = VLED + 8V < Vz + 16V
Fuse
GN2470
1.0F
TL431
Zener Voltage Boost
10K
Vz
R = Vunreg / 1.0mA
Vunreg
+ 100F
Rs
+2.5V
+
VLED
Surge Protection
AC line
220pF
180K
EMI Filter (optional) R ILED
Gate HVin
Supertex SR037
GND
Source
220nF 100k
Figure 9: Simple current drive for LED String from AC Line
Features: 1. Simple Current Regulator 2. Automatic Voltage Boost 3. Zener Boost Voltage Limit (optional) 4. EMI Filter (optional)
Vz
Zener Boost Voltage Limit (optional)
+ Vbe -
Rs
Simple Current Regulator
Iled = Vbe / Rs < 40mA
The circuit uses the SR037 or SR036 and GN2470 to drive a string of LEDs from AC power line. The LED current is regulated at up to 40mA. The LED string voltage can be up to AC line voltage (120V for 120Vac / 230V for 230VAC).
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8-Lead MSOP Package Outline (MG)
0.116 0.004 (2.946 0.102)
D
SR036/SR037
B
0.013 0.005 (0.330 0.127)
H
0.193 0.006 (4.902 0.152)
E
0.118 0.004 (3.000 0.102)
Full Circle, or Half Circle,
0.040 0.003 A (1.016 0.076)
12 4 3.0 3
A1
e
C
L
0.004 0.002 (0.102 0.051)
0.0256 BSC (0.650)
0.006 0.0003 (0.152 0.0076)
0.0215 0.006 (0.546 0.152)
8-Lead MSOP (with heat slug) Package Outline (SG)
0.1935 +/- 0.0035 (4.915 +/- 0.085)
0.1 +/- 0.01 (2.54 +/- 0.25)
Heat Slug
0.1535 +/- 0.0035 (3.9) (+/- 0.09)
0.236 +/- .008 (5.995) (+/- 0.205)
0.0165 +/- 0.0035 (0.42 +/- 0.09) 0.14 +/- 0.01 (3.555 +/- 0.255)
0.055 +/- 0.005 (1.395 +/- 0.125)
0.0085 +/- 0.0015 (0.215 +/- 0.035)
0.05 +/- 0.01 (1.27 +/- 0.25)
0.0575 +/- 0.0065 (1.46 +/- 0.16)
0.0015 +/- .0025 (0.065 +/- 0.035)
0.033 +/- 0.017 (0.84 +/- 0.43)
Measurement Legend =
Dimensions in Inches (Dimensions in Millimeters)
DOC #: DSFP-SR036SR037 B092005
13
www.supertex.com
1235 Bordeaux Drive * Sunnyvale * CA * 94089 * Telephone (408) 744-0100 * Fax (408) 222-4895
Technical Bulletin: SR03x Plate Connections
This bulletin applies to the SR036 and SR037 in the SG (Power SO-8) package. Increased efficiency and lower no-load power consumption of SR03x based regulator circuits can be achieved by assuring no electrical connections are made to the underside plate on the SR03x package. A copper area should still be employed to provide needed heat sinking, however, this copper area should be electrically floating. For maximum heat sinking capability, do not cover the copper area with solder mask. Existing PCB layouts with the plate grounded should be corrected.
Make no electrical connections to copper area
Solder underside plate to copper area for heat sinking
Early SR03x demo boards erroneously had the underside plate connected to ground. These boards will exhibit decreased efficiency and higher no load power. New, corrected demo boards may be ordered from Supertex's web site.
28APR03
www.supertex.com
1235 Bordeaux Drive * Sunnyvale * CA * 94089 * Telephone (408) 744-0100 * Fax (408) 222-4895
Technical Bulletin: SR03x EMI Reduction
SR03-based power supplies may create conducted EMI into the AC power line that exceeds FCC and CISPR requirements. This bulletin describes one technique to reduce EMI, allowing SR03-based supplies to comply with applicable requirements. Conducted EMI is largely due to the short, high-current pulse imposed on the AC line when the pass MOSFET turns on. Smoothing out this current pulse reduces the harmonic content of the current drawn from the AC line, thus reducing conducted EMI. Placing a simple RC filter before the MOSFET gate smoothes out the pulse.
EMI Suppressor Circuit
VN2460 VUNREG P6KE 400CA EMI Suppressor RG 180k VIN GATE SOURCE VREG VREG CREG 1F CG 220pF CUNREG 220F
120/230VAC 50/60Hz
SR03x
GND
The values for R G and CG may need adjustment depending on the characteristics of the chosen MOSFET and the value of CUNREG. (Higher values of CUNREG generally produce higher EMI as capacitor recharge times are shorter.) The idea is to select values of R and C to soften the edges of the current pulse, as shown below. It may be tempting to forego C G, relying instead on the MOSFETs' input capacitance. However, high dV/dt when power is first applied may cause the MOSFET to turn on due to CRSS, damaging the FET. C G protects against this possibility. Note that extending the turn-off time at the rising edge of the rectified AC increases the voltage drop across the FET, decreasing efficiency somewhat.
AC Line Current - Turn-off Edge
Without EMI Suppressor 500mA/div With EMI Suppressor
Technical Bulletin: SR03x EMI Reduction
The following spectrums show the effect of the EMI suppression technique.
120VAC/60Hz
Limits per 47CFR15.107 for Class B devices. 45mA total load.
Hot
Neutral
Average 208VAC/60Hz
Quasi-peak
(230VAC/50Hz not available) Limits per CISPR 14-1 for household appliances. 20mA total load.
Live
Neutral
Average
Quasi-peak
Technical Bulletin: SR03x EMI Reduction
The EMI reduction technique has an effect on power supply performance, as illustrated in the following graphs.
120VAC/60Hz
Efficiency
19 18 17
50%
Load Regulation
Efficiency
40%
VUNREG
without EMI suppressor with EMI suppressor
16 15 14 13 12 11 without EMI suppressor with EMI suppressor 10 20 30 40 50 60
30%
20%
0
10
20
30
40
50
60
IUNREG (mA)
10 0
IUNREG (mA)
208VAC/60Hz (230VAC/50Hz not available)
Efficiency
40% 18 17 16
Load Regulation
Efficiency
VUNREG
30%
without EMI suppressor with EMI suppressor
15 14 13 12 11
without EMI suppressor with EMI suppressor
20%
10% 0 10 20 30
10
0
10
20
30
IUNREG (mA)
IUNREG (mA)
SR03x Technical Bulletin
SR03x Power On Surge Protection
When power is first applied to an SR03x circuit near the peak of the input sine wave, there is an instantaneous step of voltage at the HVIN terminal. The same step is applied to the pass element (MOSFET or IGBT). The parasitic capacitances in the pass element (MOSFET or IGBT) form a voltage divider circuit that applies an attenuated step to the gate of the pass element in the direction to turn on the pass element. If the input step voltage is large enough, the pass element will be turned on. The high impedance gate drive of the SR03x is not strong enough to shut down the pass element in time. The pass element will conduct high current while there is a large voltage across it. This over heats the pass element and destroys it. In turn, the SR03x is also destroyed. It has been reported that this power-on circuit destruction occurs frequently on 230VAC inputs and occasionally on 120VAC inputs. The protection circuit, shown below, controls the gate drive and clamps the current through the pass element to approximately 3 Amperes (exact current not critical). This allows the SR03x enough time to shut down the pass element. As shown in the circuit diagram, the surge protection requires only a resistor and a low cost NPN transistor (MPSA06 or equivalent).
Power On Surge Protection Circuit Diagram
A110204

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