SANKEN ELECTRIC CO., LTD.
http://www.sanken-ele.co.jp/en/
STR-A6000 Series PWM Of f-Line Switching Regulator ICs
Application Information
STR-A6000-AN, Rev. 4.1
General Description
The STR-A6000 series are power ICs for switching power
supplies, incorporating a power MOSFET and a current
mode PWM controller IC in one package. To achieve low
power consumption, the product includes a startup circuit
and a standby function in the controller.
The switching modes are automatically changed accord-
ing to load conditions so that the PWM mode is in normal
operation and the burst mode is in light load condition. The
rich set of protection features helps to realize low compo-
nent counts, and high performance-to-cost power supply.
Features and Benefits
Current mode PWM control
Brown-In and Brown-Out function: auto-restart, prevents
excess input current and heat rise at low input voltage
Auto Standby function: improves efficiency by burst mode
operation in light load
Normal load operation: PWM mode
Light load operation: Burst mode
No load power consumption < 25 mW
Random Switching function: reduces EMI noise, and
simplifies EMI filters
Slope Compensation function: avoids subharmonic
oscillation
Leading Edge Blanking function
Audible Noise Suppression function during Standby mode
DIP8 package
Applications
Switching power supplies for electronic devices such as:
• Battery charger for mobile phone, digital camera, cam-
corder, electric shaver, emergency/guide light, and so forth
• Standby power supply for LCD/PDP television, desktop
PC, multi-function printer, audio equipment, and so forth
• Small switch-mode power supply (SMPS) for printer,
BD/DVD player, CD player, set-top-box, and so forth
• Auxiliary power supply for air conditioner, refrigerator,
washer, dishwasher, and so forth
Protection features
Overcurrent Protection function (OCP): pulse-by-pulse,
with input compensation function
Overvoltage Protection function (OVP): latched shutdown
Overload Protection function (OLP): auto-restart, with timer
Thermal shutdown protection (TSD): latched shutdown
Not to scale
The product lineup for the STR-A6000 series provides the following options
Part Number Features
Power MOSFET Output Power1, POUT (W)
VDSS(min)
(V)
RDS(ON)(max)
(Ω)
Open Frame Adaptor
230 VAC 85 to
265 VAC 230 VAC 85 to
265 VAC
STR-A6051M
fOSC = 67 kHz 650
3.95 30 21 20 16
STR-A6052M 2.8 35 25 23 19
STR-A6053M 1.9 41 29 26 22
STR-A6079M 800 19.2 13 9 8 6
STR-A6059H
fOSC = 100 kHz
650 6 30 19 17 11
STR-A6061H
700
3.95 35 24 21 15
STR-A6062H 2.8 38 26 23 18
STR-A6069H 6 30 19 17 11
STR-A6061HD
fOSC = 100 kHz,
two types of OCP2700
3.95 35 24 21 15
STR-A6062HD 2.8 38 26 23 18
STR-A6063HD 2.3 40 27 25 20
STR-A6069HD 6 30 19 17 11
1The listed output power is based on the thermal ratings, and the peak output power can be 120% to 140% of the value stated here. At low output volt-
age and short duty cycle, the output power may be less than the value stated here.
2The products suffixed D have an additional OCP function which operates during leading edge blanking period, to operate as protection at the condi-
tion such as output windings shorted or unusual withstand voltage of secondary-side diodes.
2
SANKEN ELECTRIC CO., LTD.
STR-A6000-AN, Rev. 4.1
Absolute Maximum Ratings
• The STR-A6059H is used as an example for the STR-A6000 series.
• Refer to the datasheet of each product for these details.
• The polarity value for current specifies a sink as "+," and a source as
"," referencing the IC.
Absolute Maximum Ratings Unless otherwise specified, TA = 25°C
Characteristic Symbol Conditions Pins Rating Unit
Drain Peak Current1IDPEAK Single pulse 8 1 1.8 A
Avalanche Energy1EAS Single pulse, VDD = 99 V, L = 20 mH 8 124mJ
ILPEAK 8 1 1.8 A
S/OCP Pin Voltage VOCP 1 3 2 to 6 V
Control Part Input Voltage VCC 5 332V
FB/OLP Pin Voltage VFB 4 3 0.3 to 14 V
FB/OLP Pin Sink Current IFB 4 3 1.0 mA
BR Pin Voltage VBR 2 3 0.3 to 7 V
BR Pin Sink Current IBR 2 3 1.0 mA
Power Dissipation of MOSFET PD1 Mounted on 15 mm × 15 mm printed circuit board 8 1 1.35 W
Power Dissipation of Control Part PD2 5 3 1.2 W
Operating Ambient Temperature2TOP –20 to 125 °C
Storage Temperature Tstg –40 to 125 °C
Channel Temperature Tch – 150 °C
1Refer to individual product datasheet for details; value differs among products.
2The recommended internal frame temperature, TF
, is 115°C (max).
Table of Contents
General Description 1
Absolute Maximum Ratings 2
Electrical Characteristics 3
Functional Block Diagram 5
Pin List Table 5
Typical Application Circuit 6
Package Diagram 7
Marking Diagram 7
Functional Description 8
Startup Operation 8
Undervoltage Lockout (UVLO) Circuit 8
Bias Assist Function 9
Constant Voltage Control Operation 9
Auto Standby Mode Function 10
Random Switching Function 11
Brown-In and Brown-Out Function 11
Overcurrent Protection Function (OCP) 13
Overvoltage Protection Function (OVP) 13
Overload Protection Function (OLP) 14
Thermal Shutdown Function (TSD) 15
Design Notes 15
Peripheral Components 15
PCB Trace Layout and Component Placement 17
Pattern Layout Example 18
Reference Design of Power Supply 19
Important Notes 21
3
SANKEN ELECTRIC CO., LTD.
STR-A6000-AN, Rev. 4.1
Electrical Characteristics
• The STR-A6059H is used as an example for the STR-A6000 series.
• Refer to the datasheet of each product for these details.
• The polarity value for current specifies a sink as "+," and a source as
"," referencing the IC.
Electrical Characteristics of Control Part Unless otherwise specified, TA = 25°C, VCC = 18 V
Characteristic Symbol Conditions Pins Min. Typ. Max. Unit
Operation Start Voltage VCC(ON) 5 3 13.8 15.3 16.8 V
Operation Stop Voltage1VCC(OFF) 5 3 7.3 8.1 8.9 V
Circuit Current in Operation ICC(ON) VCC = 12 V 5 3 – – 2.5 mA
Minimum Start Voltage VST(ON) 5 3 – 38 – V
Startup Current ISTARTUP VCC = 13.5 V 5 3 3.7 2.5 1.5 mA
Startup Current Threshold Biasing Voltage1VCC(BIAS) ICC = 100 A5 3 8.5 9.5 10.5 V
Average Operation Frequency2fOSC(AVG) 8 3 90 100 110 kHz
Frequency Modulation Deviation2f8 3 – 8 – kHz
Maximum Duty Cycle DMAX 8 377 83 89 %
Minimum On-Time2tON(MIN) – – 470 – ns
Leading Edge Blanking Time2tBW – – 280 – ns
OCP Compensation Coefficient2DPC – – 33 – mV/s
OCP Compensation Duty Cycle Limit DDPC ––36–%
OCP Threshold Voltage at Zero Duty Cycle VOCP(L) 1 3 0.70 0.78 0.86 V
OCP Threshold Voltage at 36% Duty Cycle VOCP(H) VCC = 32 V 1 3 0.81 0.9 0.99 V
Maximum Feedback Current IFB(MAX) VCC = 12 V 4 3 340 230 150 A
Minimum Feedback Current IFB(MIN) 4 3 30 15 7A
FB/OLP Pin Oscillation Stop Threshold
Voltage VFB(STB) 4 3 0.85 0.95 1.05 V
OLP Threshold Voltage VFB(OLP) 4 3 7.3 8.1 8.9 V
OLP Delay Time tOLP 4 354 68 82 ms
OLP Operation Current ICC(OLP) VCC = 12 V 5 3 – 300 600 A
FB/OLP Pin Clamp Voltage VFB(CLAMP) 4 3 11 12.8 14 V
Brown-In Threshold Voltage VBR(IN) VCC = 32 V 2 3 5.2 5.6 6 V
Brown-Out Threshold Voltage VBR(OUT) VCC = 32 V 2 3 4.45 4.8 5.15 V
BR Pin Clamp Voltage VBR(CLAMP) VCC = 32 V 2 3 6 6.4 7 V
BR Function Disabling Threshold Voltage VBR(DIS) VCC = 32 V 2 3 0.3 0.48 0.7 V
VCC Pin OVP Threshold Voltage VCC(OVP) 5 326 29 32 V
Latch Circuits Holding Current3ICC(LATCH) VCC = 9.5 V 5 3 – 700 – A
Thermal Shutdown Temperature Tj(TSD) – 135 – – °C
1VCC(BIAS) > VCC(OFF) always.
2Refer to individual product datasheet for details; value differs among products.
3A latch circuit is a circuit operated with Overvoltage Protection function (OVP) and/or Thermal Shutdown Protection function (TSD) in operation.
4
SANKEN ELECTRIC CO., LTD.
STR-A6000-AN, Rev. 4.1
Reference Parameter Comparison Between STR-A6000M Type and STR-A6000H/HD Types
Characteristic Symbol
Different ratings
UnitSTR-A6000M Type STR-A6000H / HD Types
Min. Typ. Max. Min. Typ. Max.
Average Operation Frequency fOSC(AVG) 60 67 74 90 100 110 kHz
Frequency Modulation Deviation f5 8kHz
Minimum Duty Cycle tON(MIN) 540 470 ns
Leading Edge Blanking Time tBW 340 280 ns
OCP Compensation Coefficient DPC 22 33 mV/s
Electrical Characteristics of MOSFET Unless otherwise specified, TA is 25°C
Characteristic Symbol Conditions Pins Min. Typ. Max. Unit
Drain-to-Source Breakdown Voltage* VDSS 8 – 1 650 – – V
Drain Leakage Current IDSS 8 – 1 – – 300 A
On-Resistance* RDS(ON) 8 – 1 – – 6
Switching Time* tf8 – 1 – – 250 ns
Thermal Resistance* Rch-C
The thermal resistance between
the channels of the MOSFET and
the case. Case temperature, TC, is
measured at the center of the case
top surface.
– – – 22 °C/W
*Refer to individual product datasheet for details; value differs among products.
5
SANKEN ELECTRIC CO., LTD.
STR-A6000-AN, Rev. 4.1
D/S T
VCC
5
2
4S/OCP
FB/OLP
GND
BR
DRV
PWM OSC
REG
SQ
R
Slope
Compensation
6.4 V
V
REG
Fe edback
Control
OCP
Drain Peak Current
Compe nsa tion
7 V
12.8 V
V
CC
LEB
OLP
OVP TS D
Startup
UVLO
Brown-In/
Brown-Out
7,8
1
3
Functional Block Diagram
Pin List Table
1
2
3
4
8
7
5
D/ST
D/ST
VCC
S/OCP
BR
GND
FB/OLP
Number Name Function
1 S/OCP MOSFET source, and input for Overcurrent Protection (OCP) signal
2 BR Input for Brown-In and Brown-Out detection voltage
3 GND Ground
4 FB/OLP Feedback signal input for constant voltage control signal, and input of Overload
Protection (OLP) signal
5 VCC Power supply voltage input for Control Part and input of Overvoltage Protection
(OVP) signal
6 – (Pin removed)
7, 8 D/ST MOSFET drain, and input of the startup current
6
SANKEN ELECTRIC CO., LTD.
STR-A6000-AN, Rev. 4.1
VAC
C1
C5 R1
D1
BR1
R2
C2
T1
D
P
PC 1
C3
R
OCP
C9
CRD clamp snubber
C4
C（CR）
Dumper snubber
1234
D/ST D/ST
BR
NC
S/OCP FB/OLPGND
VCC
87 5
STR-A6000
U1
D2
C10
R
C
R
B
R
A
D51
C51
R51
R52
U51
R54
R56
C52
S
PC1
R53
R55
L51
C53
VOUT
GND
VAC
C1
C5 R1
D1
BR1
R2
C2
T1
D
P
PC 1
C3
R
OCP
C9
CRD clamp snubber
C4
C（CR）
Dumper snubber
1234
D/ST D/ST
BR
NC
S/OCP FB/OLPGND
VCC
87 5
STR-A6000
U1
D2
D51
C51
R51
R52
U51
R54
R56
C52
S
PC1
R53
R55
L51
C53
VOUT
GND
Typical application circuit example, enabled Brown-In/Brown-Out function (DC line detection)
Typical application circuit example, disabled Brown-In/Brown-Out function
Typical Application Circuit
The following drawings show circuits enabled and disabled the
Brown-In/Brown-Out function.
The following design features should be observed:
• The PCB traces from the D/ST pins should be as wide as pos-
sible, in order to enhance thermal dissipation.
• In applications having a power supply specified such that VDS
has large transient surge voltages, a clamp snubber circuit of a
capacitor-resistor-diode (CRD) combination should be added
on the primary-side winding P, or a damper snubber circuit of
a capacitor (C) or a resistor-capacitor (RC) combination should
be added between the D/ST pin and the S/OCP pin.
7
SANKEN ELECTRIC CO., LTD.
STR-A6000-AN, Rev. 4.1
０～１５°
０～１５°
0.25
+0.1
-0.05
6.5
14
5
8
9.4 ±0.3
0.5 ±0.1
0.89 TYP
4.2 ±0.3
3.3
3.4 ±0.1
±0.2
(7.6 TYP)
2.54 TYP
-0.05
-0.05
±0.2
±0.57.5
+0.3
+0.3
1.0 1.52
Unit： mm
Part Number
Lot Number
Sanken Control Number
A60xxx
SK YMD
Y is the last digit of the year (0 to 9)
M is the month (1 to 9, O, N, or D)
D is a period of days (1 to 3):
1 – 1st to 10th
2 – 11th to 20th
3 – 21st to 31st
8
1
Part Number
Lot Number
Sanken Control Number
A60xxH
SK YMD D
Y is the last digit of the year (0 to 9)
M is the month (1 to 9, O, N, or D)
D is a period of days (1 to 3):
1 – 1st to 10th
2 – 11th to 20th
3 – 21st to 31st
8
1
STR-A6xxH or STR-A6xxM STR-A6xxHD
Package Diagram
Marking Diagram
Pb-free.Device composition compliant with the RoHS directive.
• DIP8 package
• The following show a representative type of DIP8.
• The pin 6 is removed to provide greater creepage and clearance isolation between
the high voltage pins (pins 7 and 8: D/ST) and the low voltage pin (pin 5: VCC).
8
SANKEN ELECTRIC CO., LTD.
STR-A6000-AN, Rev. 4.1
Functional Description
• All of the parameter values used in these descriptions are typical
values, according to the STR-A6059H specification, unless they
are specified as minimum or maximum.
• With regard to current direction, "+" indicates sink current (to-
ward the IC) and "–" indicates source current (from the IC).
Startup Operation
Figure 1 shows the VCC pin peripheral circuit, disabled the
Brown-In/Brown-Out function by connecting the BR pin trace to
the GND pin trace.
The built-in startup circuit is connected to the D/ST pin. When the
D/ST pin voltage increases to VST(ON) = 38 V, the startup circuit
starts operation.
In figure 1, the Startup Current, ISTARTUP , which is a constant
current of –2.5 mA, is provided from the IC to capacitor C2 con-
nected to the VCC pin, and it charges C2. When the VCC pin
voltage increases to VCC(ON) = 15.3 V, the IC starts operation. After
that, the startup circuit stops automatically, in order to eliminate its
own power consumption.
During the IC operation, the rectified voltage from the auxiliary
winding voltage, VD , of figure 1 becomes a power source to the
VCC pin.
The winding turns of winding D should be adjusted so that the
VCC pin voltage is applied to equation (1) within the specifica-
tions of the input voltage range and output load range of the power
supply. The target voltage of the winding D is about 15 to 20 V.
V
CC(BIAS)(max) < VCC < VCC(OVP)(min) (1)
⇒ 10.5 (V) < VCC < 26.0 (V)
The startup time, tSTART , is determined by the value of C2, and it is
approximately given as below:
z
tSTART C2|ISTARTUP|
VCC(ON) – VCC(INT)
× (2)
where:
tSTART is the startup time in s, and
VCC(INT) is the initial voltage of the VCC pin in V.
Undervoltage Lockout (UVLO) Circuit
Figure 2 shows the relationship of VCC and ICC . After the IC starts
operation, when the VCC pin voltage decreases to VCC(OFF) =
8.1 V, the IC stops switching operation by the UVLO (Undervolt-
age Lockout) circuit and reverts to the state before startup.
VAC
C1
D2 R2
C2
T1
D
P
BR1
VCC
GND
D/ST
7,8
3
5
UI
V
D
BR
2
Figure 1. VCC pin peripheral circuit
Figure 2. VCC versus ICC
V
CC
= 2.5 mA (max)
I
CC(ON)
Stop
Start
I
CC
V
CC(ON)
pin voltage
15 V
V
CC(OFF)
8.5 V
9
SANKEN ELECTRIC CO., LTD.
STR-A6000-AN, Rev. 4.1
Bias Assist Function
Figure 3 shows the VCC pin voltage behavior during the startup
period. When the VCC pin voltage increases to VCC(ON) = 15.3 V,
the IC starts operation. Thus, the circuit current, ICC
, increases,
and the VCC pin voltage begins dropping. At the same time, the
auxiliary winding voltage, VD , increases in proportion to the
output voltage rise.
Thus, the VCC pin voltage is set by the balance between dropping
due to the increase of ICC and rising due to the increase of the
auxiliary winding voltage, VD
.
Just at the turning-off of the power MOSFET, a surge voltage
occurs at the output winding. If the feedback control is activated
by the surge voltage on light load condition at startup, the output
power is restricted and the output voltage decreases.
When the VCC pin voltage decreases to VCC(OFF) = 8.1 V, the IC
stops switching operation and a startup failure occurs.
In order to prevent this, the Bias Assist function is activated when
the VCC pin voltage decreases to the Startup Current Threshold
Biasing Voltage, VCC(BIAS) = 9.5 V, during a state of operating
feedback control. While the Bias Assist function is activated, any
decrease of the VCC pin voltage is counteracted by providing the
Startup Current, ISTARTUP
, from the startup circuit. Thus, the VCC
pin voltage is kept almost constant.
By the Bias Assist function, the value of C2 is allowed to be small
and the startup time becomes shorter. Furthermore, because the
increase of VCC pin voltage becomes faster when the output
runs with excess voltage, the response time of the OVP function
becomes shorter.
It is necessary to check and adjust the startup process based on
actual operation in the application, so that the startup failure does
not occur.
Constant Voltage Control Operation
The constant output voltage control function uses current mode
control (peak current mode), which enhances response speed and
provides stable operation.
The FB/OLP pin voltage is internally added the slope compensa-
tion at the feedback control (refer to Function Block Diagram
section), and the target voltage, VSC , is generated. The IC com-
pares the voltage, VROCP , of a current detection resistor with the
target voltage, VSC , by the internal FB comparator, and controls
the peak value of VROCP so that it gets close to VSC
, as shown in
figures 4 and 5.
Time
V
CC
VCC(OFF)
VCC(ON)
VCC(BIAS)
IC startup Startup success
Target
Operating
Voltage
Bias Assist period
Increasing by
output voltage rising
Startup failure
pin voltage
Figure 3. VCC pin voltage during startup period
PC1
C3
4
FB/OLP
S/OCP
UI
I
FB
GND
R
OCP
V
ROCP
13
Figure 4. FB/OLP pin peripheral circuit
Figure 5. Drain current, ID
, and FB comparator in steady operation
VSC
Target voltage including
Slope Compensation
OCP pin voltage
FB Comparator
Drain current
VROCP
ID
+
–
10
SANKEN ELECTRIC CO., LTD.
STR-A6000-AN, Rev. 4.1
• Light load conditions
When load conditions become lighter, the output voltage, VOUT
,
increases. Thus, the feedback current from the error amplifier
on the secondary-side also increases. The feedback current is
sunk at the FB/OLP pin, transferred through a photocoupler,
PC1, and the FB/OLP pin voltage decreases. Thus, VSC
decreases, and the peak value of VROCP is controlled to be low,
and the peak drain current of ID decreases. This control prevents
the output voltage from increasing.
• Heavy load conditions
When load conditions become greater, the IC performs the
inverse operation to that described above. Thus, VSC increases
and the peak drain current of ID increases. This control prevents
the output voltage from decreasing.
In the current mode control method, when the drain current wave-
form becomes trapezoidal in continuous operating mode, even
if the peak current level set by the target voltage is constant, the
on-time fluctuates based on the initial value of the drain current.
This results in the on-time fluctuating in multiples of the funda-
mental operating frequency as shown in figure 6. This is called
the subharmonics phenomenon.
In order to avoid this, the IC incorporates the Slope Compensa-
tion function. Because the target voltage is added a down-slope
compensation signal, which reduces the peak drain current as the
on-duty gets wider relative to the FB/OLP pin signal to compen-
sate VSC, the subharmonics phenomenon is suppressed.
Even if subharmonic oscillations occur when the IC has some
excess supply being out of feedback control, such as during
startup and load shorted, this does not affect performance of
normal operation.
In the current mode control method, the FB comparator and/or
the OCP comparator may respond to the surge voltage resulting
from the drain surge current in turning-on the power MOSFET.
As a result, the power MOSFET may turn off irregularly. In order
to prevent this response to the surge voltage in turning-on the
power MOSFET, Leading Edge Blanking, tBW = 280 ns (340 ns
for STR-A6000M type), is built-in.
Auto Standby Mode Function
Auto Standby mode is activated automatically when the drain
current, ID
, reduces under light load conditions, at which ID is
less than 15% to 20% of the maximum drain current (it is in the
Overcurrent Protection state).
The operation mode becomes burst oscillation, as shown in fig-
ure 7. Burst mode reduces switching losses and improves power
supply efficiency because of periodic non-switching intervals.
Generally, to improve efficiency under light load conditions,
the frequency of the burst mode becomes just a few kilohertz.
Because the IC suppresses the peak drain current well during
burst mode, audible noises can be reduced.
If the VCC pin voltage decreases to VCC(BIAS) = 9.5 V during the
transition to the burst mode, the Bias Assist function is activated
and stabilizes the standby mode operation, because ISTARTUP is
Figure 6. Drain current, ID
, waveform in subharmonic oscillation
t
ON1
Target voltage
without Slope Compensation
t
ON2
ttt
Output
current, IOUT
Drain
current, ID
Normal operation Normal operationStandby operation
Burst oscillation
Below several kHz
Figure 7. Auto Standby mode timing
11
SANKEN ELECTRIC CO., LTD.
STR-A6000-AN, Rev. 4.1
provided to the VCC pin so that the VCC pin voltage does not
decrease to VCC(OFF).
However, if the Bias Assist function is always activated during
steady-state operation including standby mode, the power loss
increases. Therefore, the VCC pin voltage should be more than
VCC(BIAS), for example, by adjusting the turns ratio of the aux-
iliary winding and secondary-side winding and/or reducing the
value of R2 in figure 16 (refer to Peripheral Components section
for a detail of R2).
Random Switching Function
The IC modulates its switching frequency randomly within f =
± 4% superposed on the average operation frequency, fOSC(AVG)
.
The conduction noise with this function is smaller than that with-
out this function, and this function can simplify noise filtering of
the input lines of power supply.
Brown-In and Brown-Out Function
This function stops switching operation when it detects low input
line voltage, and thus prevents excessive input current and over-
heating. During Auto Standby mode, this function is disabled.
Disabled Brown-In and Brown-Out Function
When the Brown-In and Brown-Out function is unnecessary,
connect the BR pin trace to the GND pin trace so that the BR pin
voltage is VBR(DIS) = 0.48 V or less, as shown in figure 8.
Brown-In and Brown-Out Function by DC Line
Detection
The BR pin detects a voltage proportional to the DC input voltage
(C1 voltage), with the resistive voltage divider RA, RB, and RC
connected between the DC input and GND, plus C10 connected
to the BR pin, as shown in figure 8-9.
This method detects peaks of the ripple voltage of the rectified
AC input voltage, and thus it minimizes the influence of load
conditions on the detecting voltage.
During the input voltage rising from the stopped state of power
supply, when the BR pin voltage increases to VBR(DIS) = 0.48 V or
more, this function is enabled. After that, when the BR pin volt-
age increases to VBR(IN) = 5.6 V or more and the VCC pin voltage
Figure 8. The circuit used to disable the Brown-In and Brown-Out function
Figure 9. Brown-In and Brown-Out function controlled by DC line detection
2
14
87 5
3
D/ST D/ST
S/OCP
V
CC
UI
PC1
R
OCP
C3
C1
BR pin is connected to GND
GND FB/OLP
BR
C1
PC1
C3
R
OCP
1234
D/ST D/ST
BR
NC
S/OCP FB/OLP
GND
VCC
87 5
UI
C10
R
C
R
B
R
A
68 ms
V
BR(OUT)
= 4.8 V
V
BR(IN)
= 5.6 V
BR pin voltage
V
BR(DIS)
= 0.48 V
Drain current, I
D
VCC pin voltage
V
CC(ON)
V
CC(OFF)
E
IN
E
IN
I
D
12
SANKEN ELECTRIC CO., LTD.
STR-A6000-AN, Rev. 4.1
increases to VCC(ON) or more, the IC starts switching operation.
During the input voltage falling from the operated state of power
supply, when the BR pin voltage decreases to VBR(OUT) = 4.8 V or
less for about 68 ms, the IC stops switching operation.
• Component values of the BR pin peripheral circuit:
RA, RB: A few megohms. Because of high DC voltage applied
and high resistance, it is recommended to select a resistor
designed against electromigration or use a combination of
resistors in series for that to reduce each applied voltage,
according to the requirement of the application.
RC: A few hundred kilohms
C10: 100 to 1000 pF for high frequency noise rejection
Brown-In and Brown-Out Function by AC Line
Detection
The BR pin detects a voltage proportional to the AC input volt-
age, with the resistive voltage divider RA, RB, and RC connected
between one side of the AC line and GND, plus C10 connected to
the BR pin and R9 connected between the BR pin and the VCC
pin, as shown in figure 10.This method detects the AC input volt-
age, and thus it minimizes the influence from C1 charging and
discharging time, or load conditions, on the detecting voltage.
This method is set together with the High-Speed Latch Release
function.
During the input voltage rising from the stopped state of power
supply, when the BR pin voltage increases to VBR(DIS) = 0.48 V or
more, this function is enabled. After that, when the BR pin volt-
age increases to VBR(IN) = 5.6 V or more and the VCC pin voltage
increases to VCC(ON) or more, the IC starts switching operation.
During the input voltage falling from the operated state of power
supply, when the BR pin voltage decreases to VBR(OUT) = 4.8 V or
less for about 68 ms, the IC stops switching operation.
• Component values of the BR pin peripheral circuit:
RA, RB: A few megohms. Because of high DC voltage applied
and high resistance, it is recommended to select a resistor
designed against electromigration or use a combination of
resistors in series for that to reduce each applied voltage,
according to the requirement of the application.
RC: A few hundred kilohms
C10: 0.047 to 0.47 F for AC ripple rejection. This should be
adjusted according to values of RA, RB, and RC.
R9: To enable the Brown-In and Brown-Out function, this
value must be adjusted so that the BR pin voltage is more
than VBR(DIS) = 0.48 V when the VCC pin voltage decreases to
VCC(OFF) = 8.1 V.
• High-Speed Latch Release
The Brown-In and Brown-Out function by AC line detection
shown in figure 10 can quickly release the latch mode when the
AC input, VAC, is turned off.
When the Overvoltage Protection function (OVP) or Thermal
Shutdown function (TSD) are activated, the IC stops switching
Figure 10. Brown-In and Brown-Out function controlled by AC line detection
C1
PC1
C3
R
OCP
1234
D/ST D/ST
BR
NC
S/OCP FB/OLPGND
VCC
87 5
UI
C10
R
C
R
B
R
A
68 ms
V
BR(OUT)
= 4.8 V
V
BR(IN)
= 5.6 V
BR pin voltage
V
BR(DIS)
= 0.48 V
Drain current, I
D
VCC pin voltage
V
CC(ON)
V
CC(OFF)
VAC
I
D
VAC
BR1
R9
13
SANKEN ELECTRIC CO., LTD.
STR-A6000-AN, Rev. 4.1
operation in latch mode. Releasing the latch mode is done by
decreasing the VCC pin voltage below VCC(OFF) = 8.1 V after
unplugging the AC input, or by decreasing the BR pin voltage
below VBR(OUT) = 4.8 V.
This method of unplugging the AC input will spend much time
until the VCC pin voltage decreases below VCC(OFF) = 8.1 V,
because the release time is determined by discharge time of C1.
In contrast, the configuration of the BR pin peripheral circuit
shown in figure 10 makes the releasing process faster. Because
the BR pin voltage immediately decreases to VBR(OUT) = 4.8 V
or less when the AC input, VAC, is turned off, and thus the latch
mode is quickly released.
Overcurrent Protection Function (OCP)
The OCP function detects each peak drain current level of the
power MOSFET by the current detection resistor, ROCP
. When
the OCP pin voltage increases to the internal OCP thre