Enhanced, Energy Efficient,
Low Power Off-line Switcher
TinySwitch-II Features Reduce System Cost
• Fully integrated auto-restart for short circuit and open
• Built-in circuitry practically eliminates audible noise with
• Programmable line under-voltage detect feature prevents
• Frequency jittering dramatically reduces EMI (~10 dB)
• 132 kHz operation reduces transformer size – allows use
• Very tight tolerances and negligible temperature variation
• Lowest component count switcher solution
• Expanded scalable device family for low system cost
Better Cost/Performance over RCC & Linears
• Lower system cost than RCC, discrete PWM and other
• Cost effective replacement for bulky regulated linears
• Simple ON/OFF control – no loop compensation needed
• No bias winding – simpler, lower cost transformer
• Simple design practically eliminates rework in
EcoSmart®– Extremely Energy Efficient
• No load consumption <50 mW with bias winding and
• Meets California Energy Commission (CEC), Energy
• Ideal for cell-phone charger and PC standby applications
High Performance at Low Cost
• High voltage powered – ideal for charger applications
• High bandwidth provides fast turn on with no overshoot
• Current limit operation rejects line frequency ripple
• Built-in current limit and thermal protection improves
Description
TinySwitch-II integrates a 700 V power MOSFET, oscillator,
high voltage switched current source, current limit and
thermal shutdown circuitry onto a monolithic device. The
start-up and operating power are derived directly from
the voltage on the DRAIN pin, eliminating the need for
a bias winding and associated circuitry. In addition, the
of EF12.6 or EE13 cores for low cost and small size
on key parameters eases design and lowers cost
integrated/hybrid solutions
manufacturing
<250 mW without bias winding at 265 VAC input
Star, and EU requirements
safety
Figure 1. Typical Standby Application.
OUTPUT POWER TABLE
230 VAC ±15%85-265 VAC
PRODUCT
TNY263 P or G5 W7.5 W3.7 W4.7 W
TNY264 P or G
TNY265 P or G8.5 W11 W5.5 W7.5 W
TNY266 P or G
TNY267 P or G
TNY268 P or G
Tabl e 1. Not es: 1. Minimum conti nuo us power in a typical
non-ventilated enclosed adapter measured at 50
2. Minim um pra ctic al con tinu o us pow er in an open fr ame
desi g n w it h ad eq u a te he a t s in k i ng , me as u r ed at 50
ambient (See Key Applications Considerations). 3. Packages:
P: DIP-8B, G: SMD-8B. For lead-free package options, see Part
Ordering Information.
TinySwitch-II devices incorporate auto-restart, line undervoltage sense, and frequency jittering. An innovative design
minimizes audio frequency components in the simple ON/OFF
control scheme to practically eliminate audible noise with
standard taped/varnished transformer construction. The fully
integrated auto-restart circuit safely limits output power during
fault conditions such as output short circuit or open loop,
reducing component count and secondary feedback circuitry
cost. An optional line sense resistor externally programs a line
under-voltage threshold, which eliminates power down glitches
caused by the slow discharge of input storage capacitors present
in applications such as standby supplies. The operating frequency
of 132 kHz is jittered to significantly reduce both the quasi-peak
and average EMI, minimizing filtering cost.
3
Adapter
1
Frame
Open
Adapter
2
5.5 W9 W4 W6 W
10 W15 W6 W9.5 W
13 W19 W8 W12 W
16 W23 W10 W15 W
Open
1
Frame
°C ambient .
2
°C
Page 2
TNY263-268
PI-2643-030701
CLOCK
OSCILLATOR
5.8 V
4.8 V
SOURCE
(S)
SRQ
DC
MAX
BYPASS
(BP)
+
-
V
I
LIMIT
FAULT
PRESENT
CURRENT LIMIT
COMPARATOR
ENABLE
LEADING
EDGE
BLANKING
THERMAL
SHUTDOWN
+
-
DRAIN
(D)
REGULATOR
5.8 V
BYPASS PIN
UNDER-VOLTAGE
1.0 V + V
T
ENABLE/
UNDER-
VOLTAGE
(EN/UV)
Q
240 µA50 µA
LINE UNDER-VOLTAGE
RESET
AUTO-
RESTART
COUNTER
JITTER
1.0 V
6.3 V
CURRENT
LIMIT STATE
MACHINE
PI-2685-101600
EN/UV
D
S
S
S (HV RTN)
S (HV RTN)
BP
P Package (DIP-8B)
G Package (SMD-8B)
8
5
7
1
4
2
3
Figure 2. Functional Block Diagram.
Pin Functional Description
DRAIN (D) Pin:
Power MOSFET drain connection. Provides internal operating
current for both start-up and steady-state operation.
BYPASS (BP) Pin:
Connection point for a 0.1
internally generated 5.8 V supply.
ENABLE/UNDER-VOLTAGE (EN/UV) Pin:
This pin has dual functions: enable input and line under-voltage
sense. During normal operation, switching of the power
MOSFET is controlled by this pin. MOSFET switching is
terminated when a current greater than 240
this pin. This pin also senses line under-voltage conditions
through an external resistor connected to the DC line
voltage. If there is no external resistor connected to this pin,
TinySwitch-II detects its absence and disables the line undervoltage function.
2
µF external bypass capacitor for the
G
4/05
µA is drawn from
Figure 3. Pin Configuration.
SOURCE (S) Pin:
Control circuit common, internally connected to output
MOSFET source.
SOURCE (HV RTN) Pin:
Output MOSFET source connection for high voltage return.
Page 3
TNY263-268
600
05
10
136 kHz
128 kHz
V
DRAIN
Time (µs)
PI-2741-041901
500
400
300
200
100
0
TinySwitch-II Functional Description
TinySwitch-II combines a high voltage power MOSFET switch
with a power supply controller in one device. Unlike conventional
PWM (pulse width modulator) controllers, TinySwitch-II uses
a simple ON/OFF control to regulate the output voltage.
The TinySwitch-II controller consists of an oscillator,
enable circuit (sense and logic), current limit state machine,
5.8 V regulator, BYPASS pin under-voltage circuit, over-
temperature protection, current limit circuit, leading edge
blanking and a 700 V power MOSFET. TinySwitch-II
incorporates additional circuitry for line under-voltage sense,
auto-restart and frequency jitter. Figure 2 shows the functional
block diagram with the most important features.
Oscillator
The typical oscillator frequency is internally set to an average
of 132 kHz. Two signals are generated from the oscillator: the
maximum duty cycle signal (DC
indicates the beginning of each cycle.
The TinySwitch-II oscillator incorporates circuitry that
introduces a small amount of frequency jitter, typically 8 kHz
peak-to-peak, to minimize EMI emission. The modulation rate
of the frequency jitter is set to 1 kHz to optimize EMI reduction
for both average and quasi-peak emissions. The frequency jitter
should be measured with the oscilloscope triggered at the falling
edge of the DRAIN waveform. The waveform in Figure 4
illustrates the frequency jitter of the TinySwitch-II.
Enable Input and Current Limit State Machine
The enable input circuit at the EN/UV pin consists of a low
impedance source follower output set at 1.0 V. The current
through the source follower is limited to 240
current out of this pin exceeds 240 µA, a low logic level
) and the clock signal that
MAX
µA. When the
(disable) is generated at the output of the enable circuit. This
enable circuit output is sampled at the beginning of each
cycle on the rising edge of the clock signal. If high, the power
MOSFET is turned on for that cycle (enabled). If low, the power
MOSFET remains off (disabled). Since the sampling is done
only at the beginning of each cycle, subsequent changes in the
EN/UV pin voltage or current during the remainder of the
cycle are ignored.
The current limit state machine reduces the current limit by
discrete amounts at light loads when TinySwitch-II is likely to
switch in the audible frequency range. The lower current limit
raises the effective switching frequency above the audio range
and reduces the transformer flux density, including the associated
audible noise. The state machine monitors the sequence of
EN/UV pin voltage levels to determine the load condition and
adjusts the current limit level accordingly in discrete amounts.
Under most operating conditions (except when close to no-load),
the low impedance of the source follower keeps the voltage on
the EN/UV pin from going much below 1.0 V in the disabled
state. This improves the response time of the optocoupler that
is usually connected to this pin.
5.8 V Regulator and 6.3 V Shunt Voltage Clamp
The 5.8 V regulator charges the bypass capacitor connected to
the BYPASS pin to 5.8 V by drawing a current from the voltage
on the DRAIN pin whenever the MOSFET is off. The BYPASS
pin is the internal supply voltage node for the TinySwitch-II.
When the MOSFET is on, the TinySwitch-II operates from the
energy stored in the bypass capacitor. Extremely low power
consumption of the internal circuitry allows TinySwitch-II
operate continuously from current it takes from the DRAIN
pin. A bypass capacitor value of 0.1 µF is sufficient for both
high frequency decoupling and energy storage.
In addition, there is a 6.3 V shunt regulator clamping the
BYPASS pin at 6.3 V when current is provided to the BYPASS
pin through an external resistor. This facilitates powering of
TinySwitch-II externally through a bias winding to decrease the
no-load consumption to about 50 mW.
to
Figure 4. Frequency Jitter.
BYPASS Pin Under-Voltage
The BYPASS pin under-voltage circuitry disables the power
MOSFET when the BYPASS pin voltage drops below 4.8 V.
Once the BYPASS pin voltage drops below 4.8 V, it must rise
back to 5.8 V to enable (turn-on) the power MOSFET.
Over Temperature Protection
The thermal shutdown circuitry senses the die temperature. The
threshold is typically set at 135
°C with 70 °C hysteresis. When
the die temperature rises above this threshold the power MOSFET
is disabled and remains disabled until the die temperature falls
by 70 °C, at which point it is re-enabled. A large hysteresis of
G
3
4/05
Page 4
TNY263-268
PI-2699-030701
0
10002000
Time (ms)
0
5
0
10
100
200
300
V
DRAIN
V
DC-OUTPUT
70 °C (typical) is provided to prevent overheating of the PC
board due to a continuous fault condition.
Current Limit
The current limit circuit senses the current in the power MOSFET.
When this current exceeds the internal threshold (I
LIMIT
), the
power MOSFET is turned off for the remainder of that cycle. The
current limit state machine reduces the current limit threshold
by discrete amounts under medium and light loads.
The leading edge blanking circuit inhibits the current limit
comparator for a short time (t
) after the power MOSFET is
LEB
turned on. This leading edge blanking time has been set so that
current spikes caused by capacitance and secondary-side rectifier
reverse recovery time will not cause premature termination of
the switching pulse.
Auto-Restart
In the event of a fault condition such as output overload, output
short circuit, or an open loop condition, TinySwitch-II enters
into auto-restart operation. An internal counter clocked by the
oscillator gets reset every time the EN/UV pin is pulled low. If
the EN/UV pin is not pulled low for 50 ms, the power MOSFET
switching is normally disabled for 850 ms (except in the case of
line under-voltage condition, in which case it is disabled until
the condition is removed). The auto-restart alternately enables
and disables the switching of the power MOSFET until the fault
condition is removed. Figure 5 illustrates auto-restart circuit
operation in the presence of an output short circuit.
In the event of a line under-voltage condition, the switching
of the power MOSFET is disabled beyond its normal 850 ms
time until the line under-voltage condition ends.
Line Under-Voltage Sense Circuit
The DC line voltage can be monitored by connecting an external
resistor from the DC line to the EN/UV pin. During power-up
or when the switching of the power MOSFET is disabled in
auto-restart, the current into the EN/UV pin must exceed 49 µA
to initiate switching of the power MOSFET. During power-up,
this is accomplished by holding the BYPASS pin to 4.8 V while
the line under-voltage condition exists. The BYPASS pin then
rises from 4.8 V to 5.8 V when the line under-voltage condition
goes away. When the switching of the power MOSFET is
disabled in auto-restart mode and a line under-voltage condition
exists, the auto-restart counter is stopped. This stretches the
disable time beyond its normal 850 ms until the line undervoltage condition ends.
The line under-voltage circuit also detects when there is
no external resistor connected to the EN/UV pin (less than
~ 2 µA into the pin). In this case the line under-voltage function
is disabled.
TinySwitch-II Operation
TinySwitch-II devices operate in the current limit mode. When
enabled, the oscillator turns the power MOSFET on at the
beginning of each cycle. The MOSFET is turned off when the
current ramps up to the current limit or when the DC
MAX
limit is
reached. Since the highest current limit level and frequency of
a TinySwitch-II design are constant, the power delivered to the
load is proportional to the primary inductance of the transformer
and peak primary current squared. Hence, designing the supply
involves calculating the primary inductance of the transformer
for the maximum output power required. If the TinySwitch-II
is appropriately chosen for the power level, the current in the
calculated inductance will ramp up to current limit before the
DC
limit is reached.
MAX
Enable Function
TinySwitch-II senses the EN/UV pin to determine whether or not
to proceed with the next switching cycle as described earlier.
The sequence of cycles is used to determine the current limit.
Once a cycle is started, it always completes the cycle (even when
the EN/UV pin changes state half way through the cycle). This
operation results in a power supply in which the output voltage
ripple is determined by the output capacitor, amount of energy
per switch cycle and the delay of the feedback.
The EN/UV pin signal is generated on the secondary by
comparing the power supply output voltage with a reference
voltage. The EN/UV pin signal is high when the power supply
output voltage is less than the reference voltage.
In a typical implementation, the EN/UV pin is driven by an
Figure 5. TinySwitch-II Auto-Restart Operation.
G
4
4/05
optocoupler. The collector of the optocoupler transistor is
connected to the EN/UV pin and the emitter is connected to
Page 5
TNY263-268
V
DRAIN
V
EN
CLOCK
D
DRAIN
I
MAX
PI-2749-050301
V
DRAIN
V
EN
CLOCK
D
DRAIN
I
MAX
PI-2667-090700
PI-2377-091100
V
DRAIN
V
EN
CLOCK
D
DRAIN
I
MAX
the SOURCE pin. The optocoupler LED is connected in series
with a Zener diode across the DC output voltage to be regulated.
When the output voltage exceeds the target regulation voltage
level (optocoupler LED voltage drop plus Zener voltage), the
optocoupler LED will start to conduct, pulling the EN/UV pin
low. The Zener diode can be replaced by a TL431 reference
circuit for improved accuracy.
ON/OFF Operation with Current Limit State Machine
The internal clock of the TinySwitch-II runs all the time. At
Figure 6. TinySwitch-II Operation at Near Maximum Loading.
the beginning of each clock cycle, it samples the EN/UV pin to
decide whether or not to implement a switch cycle, and based
on the sequence of samples over multiple cycles, it determines
the appropriate current limit. At high loads, when the EN/UV
pin is high (less than 240
µA out of the pin), a switching cycle
with the full current limit occurs. At lighter loads, when EN/UV
is high, a switching cycle with a reduced current limit occurs.
At near maximum load, TinySwitch-II will conduct during nearly
all of its clock cycles (Figure 6). At slightly lower load, it will
“skip” additional cycles in order to maintain voltage regulation
at the power supply output (Figure 7). At medium loads, cycles
will be skipped and the current limit will be reduced (Figure 8).
At very light loads, the current limit will be reduced even further
(Figure 9). Only a small percentage of cycles will occur to
satisfy the power consumption of the power supply.
The response time of the TinySwitch-II ON/OFF control scheme
is very fast compared to normal PWM control. This provides
tight regulation and excellent transient response.
Power Up/Down
The TinySwitch-II requires only a 0.1 µF capacitor on the
BYPASS pin. Because of its small size, the time to charge this
capacitor is kept to an absolute minimum, typically 0.6 ms. Due
to the fast nature of the ON/OFF feedback, there is no overshoot
at the power supply output. When an external resistor (2 MΩ)
is connected from the positive DC input to the EN/UV pin, the
power MOSFET switching will be delayed during power-up until
the DC line voltage exceeds the threshold (100 V). Figures 10
and 11 show the power-up timing waveform of TinySwitch-II
in applications with and without an external resistor (2 MΩ)
connected to the EN/UV pin.
Figure 7. TinySwitch-II Operation at Moderately Heavy Loading.
Figure 8. TinySwitch-II Operation at Medium Loading.
4/05
G
5
Page 6
TNY263-268
PI-2661-072400
V
DRAIN
V
EN
CLOCK
D
DRAIN
I
MAX
PI-2395-030801
0
2.55
Time (s)
0
100
200
400
300
0
100
200
V
DC-INPUT
V
DRAIN
0
12
Time (ms)
0
200
400
5
0
10
0
100
200
PI-2383-030801
V
DC-INPUT
V
BYPASS
V
DRAIN
PI-2381-1030801
0
12
Time (ms)
0
200
400
5
0
10
0
100
200
V
DC-INPUT
V
BYPASS
V
DRAIN
PI-2348-030801
0
.51
Time (s)
0
100
200
300
0
100
200
400
V
DC-INPUT
V
DRAIN
Figure 9. TinySwitch-II Operation at Very Light Load.
Figure 11. TinySwitch-II Power-up without Optional External UV
Resistor Connected to EN/UV Pin.
During power-down, when an external resistor is used, the
power MOSFET will switch for 50 ms after the output loses
regulation. The power MOSFET will then remain off without
any glitches since the under-voltage function prohibits restart
when the line voltage is low.
Figure 12 illustrates a typical power-down timing waveform of
TinySwitch-II. Figure 13 illustrates a very slow power-down
timing waveform of TinySwitch-II as in standby applications.
The external resistor (2 M
Ω) is connected to the EN/UV pin
in this case to prevent unwanted restarts.
Figure 12. Normal Power-down Timing (without UV).
Figure 10. TinySwitch-II Power-up with Optional External UV
Resistor (2 MΩ) Connected to EN/UV Pin.
G
6
4/05
Figure 13. Slow Power-down Timing with Optional External
(2 M
Ω) UV Resistor Connected to EN/UV Pin.
Page 7
TNY263-268
PI-2706-080404
+ 5 V
500 mA
RTN
D1
1N4005
C1
3.3 µF
400 V
Fusible
RF1
8.2 Ω
C3
0.1
µF
C7
10 µF
10 V
85-265
VA
C
L1
2.2 mH
D2
1N4005
D3
1N4005
D4
1N4005
R2
200 kΩ
U2
LTV817
D5
1N5819
Shield
L2
3.3
µH
C5
330 µF
16 V
C2
3.3 µF
400 V
C6
100 µF
35 V
R7
100 Ω
R4
1.2
Ω
1/2 W
Q1
2N3904
R8
270 Ω
VR1
BZX79-
B3V9
3.9
V
U1
TNY264
C3
2.2 nF
D6
1N4937
R6
1 Ω
1/2
W
T1
R1
1.2 kΩ
18
45
R3
22 Ω
R9
47 Ω
C8 680 pF
Y1 Safety
TinySwitch-II
D
S
BP
EN/UV
Figure 14. 2.5 W Constant Voltage, Constant Current Battery Charger with Universal Input (85-265 VAC).
The TinySwitch-II does not require a bias winding to provide
Application Examples
power to the chip, because it draws the power directly from
the DRAIN pin (see Functional Description above). This
has two main benefits. First, for a nominal application, this
eliminates the cost of a bias winding and associated components.
Secondly, for battery charger applications, the current-voltage
characteristic often allows the output voltage to fall close to
zero volts while still delivering power. This type of application
normally requires a forward-bias winding which has many
more associated components. With TinySwitch-II, neither are
necessary. For applications that require a very low no-load power
consumption (50 mW), a resistor from a bias winding to the
BYPASS pin can provide the power to the chip. The minimum
recommended current supplied is 750 µA. The BYPASS pin in
this case will be clamped at 6.3 V. This method will eliminate the
power draw from the DRAIN pin, thereby reducing the no-load
power consumption and improving full-load efficiency.
Current Limit Operation
Each switching cycle is terminated when the DRAIN
reaches the current limit of the TinySwitch-II. Current limit
operation provides good line ripple rejection and relatively
constant power delivery independent of input voltage.
BYPASS Pin Capacitor
The BYPASS pin uses a small 0.1
decoupling the internal power supply of the TinySwitch-II.
µF ceramic capacitor for
current
The TinySwitch-II is ideal for low cost, high efficiency power
supplies in a wide range of applications such as cellular phone
chargers, PC standby, TV standby, AC adapters, motor control,
appliance control and ISDN or a DSL network termination.
The 132 kHz operation allows the use of a low cost EE13 or
EF12.6 core transformer while still providing good efficiency.
The frequency jitter in TinySwitch-II makes it possible to use a
single inductor (or two small resistors for under 3 W applications
if lower efficiency is acceptable) in conjunction with two input
capacitors for input EMI filtering. The auto-restart function
removes the need to oversize the output diode for short circuit
conditions allowing the design to be optimized for low cost
and maximum efficiency. In charger applications, it eliminates
the need for a second optocoupler and Zener diode for open
loop fault protection. Auto-restart also saves the cost of adding
a fuse or increasing the power rating of the current sense
resistors to survive reverse battery conditions. For applications
requiring under-voltage lock out (UVLO), such as PC standby,
the TinySwitch-II eliminates several components and saves
cost. TinySwitch-II is well suited for applications that require
constant voltage and c o ns t a n t curr e n t outpu t . A s
TinySwitch-II is always powered from the input high voltage, it
therefore does not rely on bias winding voltage. Consequently
this greatly simplifies designing chargers that must work down
to zero volts on the output.
4/05
G
7
Page 8
TNY263-268
2.5 W CV/CC Cell-Phone Charger
As an example, Figure 14 shows a TNY264 based 5 V,
0.5 A, cellular phone charger operating over a universal input
range (85 VAC to 265 VAC). The inductor (L1) forms a
π-filter in conjunction with C1 and C2. The resistor R1 damps
resonances in the inductor L1. Frequency jittering operation
of TinySwitch-II allows the use of a simple π-filter described
above in combination with a single low value Y1-capacitor (C8)
to meet worldwide conducted EMI standards. The addition
of a shield winding in the transformer allows conducted EMI
to be met even with the output capacitively earthed (which is
the worst case condition for EMI). The diode D6, capacitor
C3 and resistor R2 comprise the clamp circuit, limiting the
leakage inductance turn-off voltage spike on the TinySwitch-II
DRAIN pin to a safe value. The output voltage is determined
by the sum of the optocoupler U2 LED forward drop (~1 V),
and Zener diode VR1 voltage. Resistor R8 maintains a bias
current through the Zener diode to ensure it is operated close
to the Zener test current.
A simple constant current circuit is implemented using the V
BE
of transistor Q1 to sense the voltage across the current sense
resistor R4. When the drop across R4 exceeds the VBE of
transistor Q1, it turns on and takes over control of the loop by
driving the optocoupler LED. Resistor R6 assures sufficient
voltage to keep the control loop in operation down to zero volts
at the output. With the output shorted, the drop across R4 and
R6 (~1.2 V) is sufficient to keep the Q1 and LED circuit active.
Resistors R7 and R9 limit the forward current that could be
drawn through VR1 by Q1 under output short circuit conditions,
due to the voltage drop across R4 and R6.
10 and 15 W Standby Circuits
Figures 15 and 16 show examples of circuits for standby
applications. They both provide two outputs: an isolated 5 V and
a 12 V primary referenced output. The first, using TNY266P,
provides 10 W, and the second, using TNY267P, 15 W of
output power. Both operate from an input range of 140 VDC to
375 VDC, corresponding to a 230 VAC or 100/115 VAC with
doubler input. The designs take advantage of the line undervoltage detect, auto-restart and higher switching frequency of
TinySwitch-II. Operation at 132 kHz allows the use of a smaller
and lower cost transformer core, EE16 for 10 W and EE22 for
15 W. The removal of pin 6 from the 8 pin DIP TinySwitch-II
packages provides a large creepage distance which improves
reliability in high pollution environments such as fan cooled
power supplies.
Capacitor C1 provides high frequency decoupling of the high
voltage DC supply, only necessary if there is a long trace
length from the DC bulk capacitors of the main supply. The
line sense resistors R2 and R3 sense the DC input voltage
for line under-voltage. When the AC is turned off, the undervoltage detect feature of the TinySwitch-II prevents auto-restart
glitches at the output caused by the slow discharge of large
storage capacitance in the main converter. This is achieved by
preventing the TinySwitch-II from switching when the input
voltage goes below a level needed to maintain output regulation,
and keeping it off until the input voltage goes above the undervoltage threshold, when the AC is turned on again. With R2
and R3, giving a combined value of 2 MΩ, the power up undervoltage threshold is set at 200 VDC, slightly below the lowest
required operating DC input voltage, for start-up at 170 VAC,
with doubler. This feature saves several components needed to
implement the glitch-free turn-off compared with discrete or
TOPSwitch-II based designs. During turn-on the rectified DC
input voltage needs to exceed 200 V under-voltage threshold
for the power supply to start operation. But, once the power
supply is on it will continue to operate down to 140 V rectified
DC input voltage to provide the required hold up time for the
standby output.
The auxiliary primary side winding is rectified and filtered by
D2 and C2 to create a 12 V primary bias output voltage for the
main power supply primary controller. In addition, this voltage is
used to power the TinySwitch-II via R4. Although not necessary
for operation, supplying the TinySwitch-II externally reduces
the device quiescent dissipation by disabling the internal drain
derived current source normally used to keep the BYPASS pin
capacitor (C3) charged. An R4 value of 10 k
Ω provides 600 µA
into the BYPASS pin, which is slightly in excess of the current
consumption of TinySwitch-II. The excess current is safely
clamped by an on-chip active Zener diode to 6.3 V.
The secondary winding is rectified and filtered by D3 and C6.
For a 15 W design an additional output capacitor, C7, is required
due to the larger secondary ripple currents compared to the 10 W
standby design. The auto-restart function limits output current
during short circuit conditions, removing the need to over rate
D3. Switching noise filtering is provided by L1 and C8. The
5 V output is sensed by U2 and VR1. R5 is used to ensure that
the Zener diode is biased at its test current and R6 centers the
output voltage at 5 V.
In many cases the Zener regulation method provides sufficient
accuracy (typically ± 6% over a 0 °C to 50
°C temperature
range). This is possible because TinySwitch-II limits the
dynamic range of the optocoupler LED current, allowing the
Zener diode to operate at near constant bias current. However,
if higher accuracy is required, a TL431 precision reference IC
may be used to replace VR1.
G
8
4/05
Page 9
TNY263-268
C1
0.01 µF
1 kV
140-375
VDC
INPUT
L1
10 µH
2 A
R5
680 Ω
R6
59 Ω
1%
D3
1N5822
U1
TNY266P
C5
2.2 nF
1 kV
D1
1N4005GP
U2
TLP181Y
VR1
BZX79B3V9
5
4
2
1
10
8
TinySwitch-II
D
S
BP
+5 V
2
A
RTN
C2
82 µF
35 V
C8
470 µF
10 V
PI-2713-080404
C4
1 nF Y1
D2
1N4148
EN
+12 VDC
20 mA
0 V
C3
0.1 µF
50 V
R4
10 kΩ
C6
1000 µF
10 V
R2
1 MΩ
R3
1 MΩ
R1
200 kΩ
T1
PERFORMANCE SUMMARY
Continuous Output Power: 10.24 W
Efficiency: ≥ 75%
C1
0.01 µF
1 kV
140-375
VDC
INPUT
L1
10 µH
3 A
R5
680 Ω
D3
SB540
U1
TNY267P
C5
2.2 nF
1 kV
D1
1N4005GP
U2
TLP181Y
PERFORMANCE SUMMARY
Continuous Output Power: 15.24 W
Efficiency: ≥ 78%
5
4
2
1
10
8
TinySwitch-II
D
S
BP
+5 V
3
A
RTN
C2
82 µF
35 V
C8
470 µF
10 V
PI-2712-080404
C4
1 nF Y1
D2
1N4148
EN
+12 VDC
20 mA
0 V
C3
0.1 µF
50 V
R4
10 kΩ
C7
1000 µF
10 V
C6
1000 µF
10 V
R2
1 MΩ
R3
1 MΩ
R1
100 kΩ
T1
R6
59 Ω
1%
VR1
BZX79B3V9
Figure 15. 10 W Standby Supply.
Figure 16. 15 W Standby Supply.
G
9
4/05
Page 10
TNY263-268
Key Application Considerations
TinySwitch-II vs. TinySwitch
Table 2 compares the features and performance differences
between the TNY254 device of the TinySwitch family with
the TinySwitch-II family of devices. Many of the new features
eliminate the need for or reduce the cost of circuit components.
Other features simplify the design and enhance performance.
Function
Switching Frequency
and Tolerance
Temperature Variation
(0-100 °C)**
Active Frequency JitterN/A*±4 kHz• Lower EMI minimizing filter
Transformer Audible
Noise Reduction
Line UV DetectN/A*Single resistor
Current Limit Tolerance
Temperature Variation
(0-100 °C)**
Auto-RestartN/A*6% effective on-time• Limits output short-circuit current
BYPASS Pin Zener
Clamp
DRAIN Creepage at
Package
TinySwitch
TNY254
44 kHz ±10% (at 25 °C)
+8%
N/A*Yes–built into controller• Practically eliminates audible
±11% (at 25
-8%
N/A*Internally clamped to
0.037 in. / 0.94 mm0.137 in. / 3.48 mm• Greater immunity to arcing as a
°C)
132 kHz ±6% (at 25 °C)
+2%
programmable
±7% (at 25 °C)
0%
6.3 V
Design
Output Power
Table 1 (front page) shows the practical continuous output power
levels that can be obtained under the following conditions:
1. The minimum DC input voltage is 90 V or higher for
85 VAC input, or 240 V or higher for 230 VAC input or
115 VAC input with a voltage doubler. This corresponds to
a filter capacitor of 3 µF/W for universal input and 1 µF/W
for 230 VAC or 115 VAC with doubler input.
TinySwitch-II
TNY263-268
• Smaller transformer for low cost
• Ease of design
• Manufacturability
• Optimum design for lower cost
component costs
noise with ordinary dip varnished
transformer – no special
construction or gluing required
• Prevents power on/off glitches
• Increases power capability and
simplifies design for high volume
manufacturing
to less than full load current
- No output diode size penalty
• Protects load in open loop fault
conditions
- No additional components
required
• Allows
powered from a low voltage bias
winding to improve efficiency and
to reduce on-chip power
dissipation
result of dust, debris or other
contaminants build-up
TinySwitch-II
Advantages
TinySwitch-II
to be
*Not available. ** See typical performance curves.
Table 2. Comparison Between TinySwitch and TinySwitch-II.
G
10
4/05
Page 11
TNY263-268
2. A secondary output of 5 V with a Schottky rectifier diode.
3. Assumed efficiency of 77% (TNY267 & TNY268),
75% (TNY265 & TNY266) and 73% (TNY263 & TNY264).
4. The parts are board mounted with SOURCE pins soldered
to sufficient area of copper to keep the die temperature at
or below 100 °C.
In addition to the thermal environment (sealed enclosure,
ventilated, open frame, etc.), the maximum power capability
of TinySwitch-II in a given application depends on transformer
core size and design (continuous or discontinuous), efficiency,
minimum specified input voltage, input storage capacitance,
output voltage, output diode forward drop, etc., and can be
different from the values shown in Table 1.
Audible Noise
The TinySwitch-II practically eliminates any transformer audio
noise using simple ordinary varnished transformer construction.
No gluing of the cores is needed. The audio noise reduction
is accomplished by the TinySwitch-II controller reducing the
current limit in discrete steps as the load is reduced. This
minimizes the flux density in the transformer when switching
at audio frequencies.
Worst Case EMI & Efficiency Measurement
Since identical TinySwitch-II supplies may operate at several
different frequencies under the same load and line conditions,
care must be taken to ensure that measurements are made under
worst case conditions. When measuring efficiency or EMI verify
that the TinySwitch-II is operating at maximum frequency and
that measurements are made at both low and high line input
voltages to ensure the worst case result is obtained.
Layout
Single Point Grounding
Use a single point ground connection at the SOURCE pin for
the BYPASS pin capacitor and the Input Filter Capacitor
(see Figure 17).
Primary Loop Area
The area of the primary loop that connects the input filter
capacitor, transformer primary and TinySwitch-II together
should be kept as small as possible.
Primary Clamp Circuit
A clamp is used to limit peak voltage on the DRAIN pin at
turn-off. This can be achieved by using an RCD clamp (as
shown in Figure 14). A Zener and diode clamp (200 V) across
the primary or a single 550 V Zener clamp from DRAIN to
SOURCE can also be used. In all cases care should be taken
to minimize the circuit path from the clamp components to the
transformer and TinySwitch-II.
Thermal Considerations
Copper underneath the TinySwitch-II acts not only as a single
point ground, but also as a heatsink. The hatched areas shown
in Figure 17 should be maximized for good heat sinking of
TinySwitch-II and the same applies to the output diode.
EN/UV pin
If a line under-voltage detect resistor is used then the resistor
should be mounted as close as possible to the EN/UV pin to
minimize noise pick up.
The voltage rating of a resistor should be considered for the undervoltage detect (Figure 15: R2, R3) resistors. For 1/4 W resistors,
the voltage rating is typically 200 V continuous, whereas for
1/2 W resistors the rating is typically 400 V continuous.
Y-Capacitor
The placement of the Y-capacitor should be directly from the
primary bulk capacitor positive rail to the common/return
terminal on the secondary side. Such placement will maximize
the EMI benefit of the Y-capacitor and avoid problems in
common-mode surge testing.
Optocoupler
It is important to maintain the minimum circuit path from
the optocoupler transistor to the TinySwitch-II EN/UV and
SOURCE pins to minimize noise coupling.
The EN/UV pin connection to the optocoupler should be kept
to an absolute minimum (less than 12.7 mm or 0.5 in.), and
this connection should be kept away from the DRAIN pin
(minimum of 5.1 mm or 0.2 in.).
Output Diode
For best performance, the area of the loop connecting the secondary
winding, the output diode and the output filter capacitor, should
be minimized. See Figure 17 for optimized layout. In addition,
sufficient copper area should be provided at the anode and
cathode terminals of the diode for adequate heatsinking.
Input and Output Filter Capacitors
There are constrictions in the traces connected to the input and
output filter capacitors. These constrictions are present for two
reasons. The first is to force all the high frequency currents
to flow through the capacitor (if the trace were wide then it
could flow around the capacitor). Secondly, the constrictions
minimize the heat transferred from the TinySwitch-II to the input
filter capacitor and from the secondary diode to the output filter
capacitor. The common/return (the negative output terminal
in Figure 17) terminal of the output filter capacitor should be
connected with a short, low impedance path to the secondary
winding. In addition, the common/return output connection
should be taken directly from the secondary winding pin and
not from the Y-capacitor connection point.
4/05
G
11
Page 12
TNY263-268
TOP VIEW
PI-2707-012901
Y1-
Capacitor
Opto-
coupler
D
EN/UV
BP
+
—
HV
+—
DC
Out
Input Filter Capacitor
Output Filter Capacitor
Safety Spacing
Maximize hatched copper
areas ( ) for optimum
heat sinking
S
S
SEC
C
BP
TinySwitch-II
PRI
T
r
a
n
s
f
o
r
m
e
r
Figure 17. Recommended Circuit Board Layout for TinySwitch-II with Under-Voltage Lock Out Resistor.
PC Board Cleaning
Power Integrations does not recommend the use of “no clean”
For the m o s t u p -t o - da t e i n fo r m at i on v i si t t h e
PI website at: www.powerint.com.
flux.
12
G
4/05
Page 13
TNY263-268
ABSOLUTE MAXIMUM RATINGS
DRAIN Voltage .................................. ................ -0.3 V to 700 V
DRAIN Peak Current: TNY263......................................400 mA
TNY264......................................400 mA
TNY265......................................440 mA
TNY266......................................560 mA
TNY267......................................720 mA
TNY268......................................880 mA
EN/UV Voltage ................................................ -0.3 V to 9 V
EN/UV Current .................................................... 100 mA
BYPASS Voltage .................................................. -0.3 V to 9 V
Storage Temperature ......................................-65 °C to 150 °C
....................................................... 260 °C
(2)
.................-40 °C to 150 °C
Notes:
1. All voltages referenced to SOURCE, TA = 25 °C.
2. Normally limited by internal circuitry.
3. 1/16 in. from case for 5 seconds.
4. Maximum ratings specified may be applied one at a time,
without causing permanent damage to the product. Exposure to Absolute Maximum Rating conditions for extended periods of time may affect product reliability.
Notes:
1. Measured on the SOURCE pin close to plastic interface.
2. Soldered to 0.36 sq. in. (232 mm2), 2 oz. (610 g/m2) copper clad.
3. Soldered to 1 sq. in. (645 mm2), 2 oz. (610 g/m2) copper clad.
MinTypMaxUnits
CONTROL FUNCTIONS
Output Frequency
Maximum Duty
Cycle
EN/UV Pin Turnoff
Threshold Current
EN/UV Pin
Voltage
f
DC
V
OSC
I
DIS
I
MAX
EN
S1
DRAIN Supply
Current
I
I
S2
CH1
BYPASS Pin
Charge Current
I
CH2
TJ = 25 °C
See Figure 4
TJ = -40 °C to 125 °C-300-240-170µA
EN/UV Open
(MOSFET
Switching)
See Note A, B
VBP = 0 V,
TJ = 25 °C
See Note C, D
VBP = 4 V,
TJ = 25 °C
See Note C, D
Average124132140
Peak-Peak Jitter8
S1 Open626568%
I
= -125 µA0.41.01.5
EN/UV
I
= 25 µA1.32.32.7
EN/UV
V
= 0 V430500µA
EN/UV
TNY263200250
TNY264225270
TNY265245295
TNY266265320
TNY267315380
TNY268380460
TNY263-264-5.5-3.3-1.8
TNY265-268-7.5-4.6-2.5
TNY263-264-3.8-2.0-1.0
TNY265-268-4.5-3.0-1.5
kHz
V
µA
mA
G
13
4/05
Page 14
TNY263-268
ParameterSymbol
SOURCE = 0 V; TJ = -40 to 125 °C
CONTROL FUNCTIONS (cont.)
Conditions
See Figure 18
(Unless Otherwise Specified)
MinTypMaxUnits
BYPASS Pin
Voltage
BYPASS Pin
Voltage Hysteresis
V
V
EN/UV Pin Line
Under-Voltage
I
Threshold
CIRCUIT PROTECTION
Current Limit
I
BP
BPH
LUV
LIMIT
TNY263
TJ = 25 °C
TNY264
TJ = 25 °C
TNY265
TJ = 25 °C
TNY266
TJ = 25 °C
TNY267
TJ = 25 °C
TNY268
TJ = 25 °C
See Note C5.65.856.15V
0.800.951.20V
TJ = 25 °C444954µA
di/dt = 42 mA/µs
See Note E
di/dt = 50 mA/µs
See Note E
di/dt = 55 mA/µs
See Note E
di/dt = 70 mA/µs
See Note E
di/dt = 90 mA/µs
See Note E
di/dt = 110 mA/µs
See Note E
195210225
233250267
255275295
mA
325350375
419450481
512550588
Initial Current Limit
Leading Edge
Blanking Time
Current Limit
Delay
Thermal Shutdown
Temperature
Thermal Shutdown
Hysteresis
G
14
4/05
I
t
t
INIT
LEB
ILD
See Figure 21
TJ = 25 °C
TJ = 25 °C
See Note F
TJ = 25 °C
See Note F, G
0.65 x
I
LIMIT(MIN)
170215ns
150ns
125135150°C
70°C
mA
Page 15
ParameterSymbol
OUTPUT
Conditions
SOURCE = 0 V; TJ = -40 to 125 °C
See Figure 18
(Unless Otherwise Specified)
TNY263
ID = 21 mA
TJ = 25 °C3338
TJ = 100 °C5057
TNY263-268
MinTypMaxUnits
ON-State
Resistance
OFF-State Drain
Leakage Current
Breakdown
Voltage
Rise Time
Fall Time
Drain Supply
Voltage
R
I
BV
DS(ON)
DSS
DSS
t
R
t
F
TNY264
ID = 25 mA
TNY265
ID = 28 mA
TNY266
ID = 35 mA
TNY267
ID = 45 mA
TNY268
ID = 55 mA
VBP = 6.2 V,
V
= 0 V,
EN/UV
VDS = 560 V,
TJ = 125 °C
VBP = 6.2 V, V
TJ = 25 °C2832
TJ = 100 °C4248
TJ = 25 °C 1922
TJ = 100 °C2933
TJ = 25 °C 1416
TJ = 100 °C2124
TJ = 25 °C7.89.0
TJ = 100 °C11.713.5
TJ = 25 °C5.26.0
TJ = 100 °C7.89.0
TNY263-26650
TNY267-268100
= 0 V,
EN/UV
See Note H, TJ = 25 °C
Measured in a Typical Flyback
Converter Application
Ω
µA
700V
50ns
50ns
50V
Output EN/UV
Delay
Output Disable
Setup Time
Auto-Restart
ON-Time
Auto-Restart
Duty Cycle
t
EN/UV
t
DST
t
DC
AR
AR
See Figure 2010µs
0.5µs
TJ = 25 °C
See Note I
50ms
5.6%
G
4/05
15
Page 16
TNY263-268
NOTES:
A. Total current consumption is the sum of IS1 and I
switching) and the sum of IS2 and I
when EN/UV pin is open (MOSFET switching).
DSS
B Since the output MOSFET is switching, it is difficult to isolate the switching current from the supply current at the
DRAIN. An alternative is to measure the BYPASS pin current at 6.1 V.
C. BYPASS pin is not intended for sourcing supply current to external circuitry.
D. See Typical Performance Characteristics section for BYPASS pin start-up charging waveform.
E. For current limit at other di/dt values, refer to Figure 25.
F. This parameter is derived from characterization.
when EN/UV pin is shorted to ground (MOSFET not
DSS
G. This parameter is derived from the change in current limit measured at 1X and 4X of the di/dt shown in the I
specification.
H. Breakdown voltage may be checked against minimum BV
to but not exceeding minimum BV
DSS
.
specification by ramping the DRAIN pin voltage up
DSS
I. Auto-restart on time has the same temperature characteristics as the oscillator (inversely proportional to
frequency).
LIMIT
16
G
4/05
Page 17
Figure 18. TinySwitch-II General Test Circuit.
PI-2686-101700
0.1 µF
10 V
50 V
470 Ω
5 W
S2
470 Ω
NOTE: This test circuit is not applicable for current limit or output characteristic measurements.
Figure 30. Under-voltage Threshold vs. Temperature.
Figure 29. Drain Capacitance Power.
4/05
G
19
Page 20
TNY263-268
Notes:
1. Package dimensions conform to JEDEC specification
MS-001-AB (Issue B 7/85) for standard dual-in-line (DIP)
package with .300 inch row spacing.
2. Controlling dimensions are inches. Millimeter sizes are
shown in parentheses.
3. Dimensions shown do not include mold flash or other
protrusions. Mold flash or protrusions shall not exceed
.006 (.15) on any side.
4. Pin locations start with Pin 1, and continue counter-clock wise to Pin 8 when viewed from the top. The notch and/or
dimple are aids in locating Pin 1. Pin 6 is omitted.
5. Minimum metal to metal spacing at the package body for
the omitted lead location is .137 inch (3.48 mm).
6. Lead width measured at package body.
7. Lead spacing measured with the leads constrained to be
perpendicular to plane T.
.008 (.20)
.015 (.38)
.300 (7.62) BSC
(NOTE 7)
.300 (7.62)
.390 (9.91)
.367 (9.32)
.387 (9.83)
.240 (6.10)
.260 (6.60)
.125 (3.18)
.145 (3.68)
.057 (1.45)
.068 (1.73)
.120 (3.05)
.140 (3.56)
.015 (.38)
MINIMUM
.048 (1.22)
.053 (1.35)
.100 (2.54) BSC
.014 (.36)
.022 (.56)
-E-
Pin 1
SEATING
PLANE
-D-
-T-
P08B
DIP-8B
PI-2551-121504
D S
.004 (.10)
⊕
T E D S
.010 (.25) M
⊕
(NOTE 6)
.137 (3.48)
MINIMUM
PART ORDERING INFORMATION
TNY 264 G N - TL
TinySwitch Product Family
Series Number
Package Identifier
GPlastic Surface Mount SMD-8B
PPlastic DIP-8B
Lead Finish
Blank Standard (Sn Pb)
NPure Matte Tin (Pb-Free)
Tape & Reel and Other Options
Blank Standard Configurations
TLTape & Reel, 1 k pcs minimum, G Package only
20
G
4/05
Page 21
TNY263-268
SMD-8B
PI-2546-121504
.004 (.10)
.012 (.30)
.036 (0.91)
.044 (1.12)
.004 (.10)
0 -
°
8
°
.367 (9.32)
.387 (9.83)
.048 (1.22)
.009 (.23)
.053 (1.35)
.032 (.81)
.037 (.94)
.125 (3.18)
.145 (3.68)
-D-
Notes:
1. Controlling dimensions are
inches. Millimeter sizes are
shown in parentheses.
2. Dimensions shown do not
include mold flash or other
protrusions. Mold flash or
protrusions shall not exceed
.006 (.15) on any side.
3. Pin locations start with Pin 1,
and continue counter-clock wise to Pin 8 when viewed
from the top. Pin 6 is omitted.
4. Minimum metal to metal
spacing at the package body
for the omitted lead location
is .137 inch (3.48 mm).
5. Lead width measured at
package body.
6. D and E are referenced
datums on the package
body
.
.057 (1.45)
.068 (1.73)
(NOTE 5)
E S
.100 (2.54) (BSC)
.372 (9.45)
.240 (6.10)
.388 (9.86)
.137 (3.48)
MINIMUM
.260 (6.60)
.010 (.25)
-E-
Pin 1
D S
.004 (.10)
⊕
⊕
G08B
.420
.046
.060
.060
.046
.080
Pin
1
.086
.186
.286
Solder Pad Dimensions
4/05
G
21
Page 22
TNY263-268
22
G
4/05
Page 23
TNY263-268
Revision NotesDate
A-3/01
B1) Corrected first page spacing and sentence in description describing innovative design.
2) Corrected Frequency Jitter in Figure 4 and Frequency Jitter in Parameter Table.
3) Added last sentence to Over Temperature Protection section.
4) Clarified detecting when there is no external resistor connected to the EN/UV pin.
5) Corrected Figure 6 and its description in the text.
6) Corrected formatting, grammer and style errors in text and figures.
7) Corrected and moved Worst Case EMI & Efficiency Measurement section.
8) Added PC Board Cleaning section.
9) Replaced Figure 21 and SMD-8B Package Drawing.
C1) Corrected θJA for P/G package.
2) Updated Figures 15 and 16 and text description for Zener performance.
3) Corrected DIP-8B and SMD-8B Package Drawings.
D1) Corrected EN/UV under-voltage threshold in text.
2) Corrected 2 MΩ connected between positive DC input to EN/UV pin in text and Figures 15 and 16.
E1) Added TNY263 and TNY265.4/04
F1) Added lead-free ordering information.12/04
G1) Typographical correction in OFF-STATE Drain Leakage Current parameter condition.
2) Removed IDS condition from BV
parameter and added new Note H.
DSS
3) Added Note 4 to Absolute Maximum Ratings specifications.
7/01
4/03
3/04
4/05
4/05
G
23
Page 24
TNY263-268
For the latest updates, visit our website:www.powerint.com
Power Integrations reserves the right to make changes to its products at any time to improve reliability or manufacturability. Power Integrations does not assume
any liability arising from the use of any device or circuit described herein. POWER INTEGRATIONS MAKES NO WARRANTY HEREIN AND SPECIFICALLY
DISCLAIMS ALL WARRANTIES INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
PARTICULAR PURPOSE, AND NON-INFRINGEMENT OF THIRD PARTY RIGHTS.
PATENT INFORMATION
The products and applications illustrated herein (including transformer construction and circuits external to the products) may be covered by one or more U.S.
and foreign patents, or potentially by pending U.S. and foreign patent applications assigned to Power Integrations. A complete list of Power Integrationsʼ patents
may be found at www.powerint.com. Power Integrations grants its customers a license under certain patent rights as set forth at http://www.powerint.com/ip.htm.
LIFE SUPPORT POLICY
POWER INTEGRATIONSʼ PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS
WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF POWER INTEGRATIONS. As used herein:
1. A Life support device or system is one which, (i) is intended for surgical implant into the body, or (ii) supports or sustains life, and (iii) whose failure to perform,
when properly used in accordance with instructions for use, can be reasonably expected to result in significant injury or death to the user.
2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life
support device or system, or to affect its safety or effectiveness.