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 V
SOURCE
. An unregulated DC voltage will develop on V
SOURCE
.
Once HV
IN
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
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ig
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o
e
N
D
w
e
N
r
o
F
~
18V Unregulated
GN2470
1.0µF
470µF
Surge
Protection
Gate
120VAC
or
230VAC
HV
IN
SR036
or
SR037
V
SOURCE
V
OUT
SR036:
V
OUT
=
3.3V
Regulated
SR037:
V
OUT
= 5.0V Regulated
1.0µF
B092005
B092005
1
SR036/SR037
Ordering Information
V
OUT
3.3V
5.0V
Packa
g
e Options
MSOP-
8
SR036MG*
SR037MG*
SO-
8
w/ Heat Slu
g
SR036SG
SR037SG
* Product supplied on 2500 piece carrier tape reel.
Absolute Maximum Ratings*
V
IN
, High Voltage Input
V
OUT
, 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 2cm
2
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
HV
IN
1
2
3
4
8
7
6
5
Gate
Source
V
OUT
N/C
+6.0V
-65°C to +150°C
+300°C
300mW
1.50W
1
N/C
N/C
GND
MSOP-8
(top view)
HV
IN
N/C
N/C
GND
1
2
3
4
8
7
6
5
Gate
Source
V
OUT
N/C
SO-8 Slug
Make no electrical connections
to Backside Plate
(top view)
Electrical Characteristics
(Over operating supply voltages unless otherwise specified, T
A
=0°C to +125°C)
Symbol
HV
IN
V
TH
V
GS
V
GATE
V
OUT
∆V
OUT
Freq
Input voltage
HV
IN
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
V
OUT
load regulation
Input AC frequency
40
SR036
SR037
40
±10
1
8
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
V
SOURCE
= 10V
V
SOURCE
= 10V
V
SOURCE
= 10V,
I
Load
= 0 to 50mA (1)
I
GS
= ±100µA
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
≈
V
IN
2
+
(16V
−
V
OUT
)
×
I
OUT
185k
Ω
Where I
OUT
is the load on the regulated output
2
B092005
SR036/SR037
Typical Performance Curves
Gate Clamp
25
60
HV
IN
(off)
20
50
40
Vgate (V)
HV
IN
(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
V
OUT
(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
125°C
1800
5.00
25°C
-40°C
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
HV
IN
(V)
Load Regulation (SR037)
1500
1200
I
IN
(µA)
900
V
OUT
(V)
Source=15V
25°C
Source=8V
25°C
300
0
20
30
40
50
HV
IN
(V)
B092005
I
OUT
(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 V
TH
threshold, the pass transistor
is turned on. The pass transistor is turned off when the rectified
AC is above HV
IN(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.
HV
IN
V
REF
CM
Gate
Source
Reg
V
OUT
GND
Switch
ON
HV
IN
V
TH
V
REG
not to
scale
V
UNREG
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 P
BIAS
= V
IN2
/ 185k½ where V
IN
is the input voltage in V
RMS
. The second source of power dissipation is the 3.3/5V linear
regulator and may be calculated from P
REG
= (16V - V
OUT
) * I
REG
, where V
OUT
is 3.3V or 5V, and I
REG
is the load current on the 3.3/5V output.
The total power dissipated by the SR03x is the sum of these two: P
BIAS
+ P
REG
. (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 2cm
2
of exposed copper area on
the PCB.
Power is also dissipated by the pass transistor. Power dissipated by the transistor will be (16V * I
TOTAL
) * (1/Eff -1) where I
TOTAL
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 5cm
2
of exposed copper area on the PCB for heatsinking.
Transformers
4
B092005
SR036/SR037
Using a MOSFET in place of an IGBT
VN2460
1.0µF
Gate
~
18V Unregulated
270µF
Surge
Protection
120VAC
or
230VAC
HV
IN
SR036
or SR037
V
SOURCE
V
OUT
SR036: V
OUT
=3.3V Regulated
SR037: V
OUT
=5.0V Regulated
1.0µF
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
P
UNREG
(W)
Efficiency and EMI Test Circuit
120/230VAC
50/60Hz
GN2470
P6KE
400CA
EMI
Suppressor
R
G
180kΩ
V
IN
GATE
SOURCE
V
REG
V
REG
C
REG
1.0μF
C
G
220pF
1.0μF
V
UNREG
220μF (VN2460)
470μF (GN2470)
SR03x
GND
B092005
5
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