POWERINT TNY274

TNY274-280
TinySwitch-III Family
®
Energy Efficient, Off-Line Switcher with
Enhanced Flexibility and Extended Power Range
Product Highlights
Lowest System Cost with Enhanced Flexibility
• Simple ON/OFF control, no loop compensation needed
• Selectable current limit through BP/M capacitor value
- Higher current limit extends peak power or, in open
frame applications, maximum continuous power
- Lower current limit improves efficiency in enclosed
adapters/chargers
- Allows optimum TinySwitch-III choice by swapping
devices with no other circuit redesign
• Tight I2f parameter tolerance reduces system cost
- Maximizes MOSFET and magnetics power delivery
- Minimizes max overload power, reducing cost of
transformer, primary clamp & secondary components
• ON-time extension – extends low line regulation range/
hold-up time to reduce input bulk capacitance
• Self-biased: no bias winding or bias components
• Frequency jittering reduces EMI filter costs
• Pin-out simplifies heatsinking to the PCB
• SOURCE pins are electrically quiet for low EMI
Enhanced Safety and Reliability Features
• Accurate hysteretic thermal shutdown protection with
automatic recovery eliminates need for manual reset
• Improved auto-restart delivers <3% of maximum power
in short circuit and open loop fault conditions
• Output overvoltage shutdown with optional Zener
• Line under-voltage detect threshold set using a single
optional resistor
• Very low component count enhances reliability and
enables single-sided printed circuit board layout
• High bandwidth provides fast turn on with no overshoot
and excellent transient load response
• Extended creepage between DRAIN and all other pins
improves field reliability
®
EcoSmart – Extremely Energy Efficient
• Easily meets all global energy efficiency regulations
• No-load <150 mW at 265 VAC without bias winding,
<50 mW with bias winding
• ON/OFF control provides constant efficiency down to
very light loads – ideal for mandatory CEC regulations
and 1 W PC standby requirements
Applications
• Chargers/adapters for cell/cordless phones, PDAs, digital
cameras, MP3/portable audio, shavers, etc.
+
+
DC
Output
Wide-Range
HV DC Input
D
EN/UV
BP/M
TinySwitch-III
S
PI-4095-082205
Figure 1. Typical Standby Application.
OUTPUT POWER TABLE
230 VAC ±15%
PRODUCT3
85-265 VAC
Peak or
Peak or
Adapter1 Open Adapter1 Open
Frame2
Frame2
TNY274 P or G
TNY275 P or G
TNY276 P or G
TNY277 P or G
TNY278 P or G
TNY279 P or G
TNY280 P or G
6W
8.5 W
10 W
13 W
16 W
18 W
20 W
11 W
15 W
19 W
23.5 W
28 W
32 W
36.5 W
5W
6W
7W
8W
10 W
12 W
14 W
8.5 W
11.5 W
15 W
18 W
21.5 W
25 W
28.5 W
Table 1. Notes: 1. Minimum continuous power in a typical nonventilated enclosed adapter measured at 50 °C ambient. Use of an
external heatsink will increase power capability 2. Minimum peak
power capability in any design or minimum continuous power in an
open frame design (see Key Application Considerations). 3. Packages:
P: DIP-8C, G: SMD-8C. See Part Ordering Information.
•
•
•
PC Standby and other auxiliary supplies
DVD/PVR and other low power set top decoders
Supplies for appliances, industrial systems, metering, etc.
Description
TinySwitch-III incorporates a 700 V power MOSFET, oscillator,
high voltage switched current source, current limit (user
selectable) and thermal shutdown circuitry. The IC family uses
an ON/OFF control scheme and offers a design flexible solution
with a low system cost and extended power capability.
February 2006
TNY274-280
BYPASS/
MULTI-FUNCTION
(BP/M)
DRAIN
(D)
REGULATOR
5.85 V
LINE UNDER-VOLTAGE
115 µA
25 µA
FAULT
PRESENT
AUTORESTART
COUNTER
6.4 V
RESET
BYPASS PIN
UNDER-VOLTAGE
+
-
5.85 V
4.9 V
CURRENT
LIMIT STATE
MACHINE
VI
LIMIT
CURRENT LIMIT
COMPARATOR
ENABLE
+
JITTER
CLOCK
1.0 V + VT
DCMAX
THERMAL
SHUTDOWN
OSCILLATOR
ENABLE/
UNDERVOLTAGE
(EN/UV)
1.0 V
S
Q
R
Q
LEADING
EDGE
BLANKING
SOURCE
(S)
PI-4077-013106
Figure 2. Functional Block Diagram.
Pin Functional Description
DRAIN (D) Pin:
This pin is the power MOSFET drain connection. It provides
internal operating current for both start-up and steady-state
operation.
BYPASS/MULTI-FUNCTION (BP/M) Pin:
This pin has multiple functions:
1. It is the connection point for an external bypass capacitor
for the internally generated 5.85 V supply.
2. It is a mode selector for the current limit value, depending
on the value of the capacitance added. Use of a 0.1 µF
capacitor results in the standard current limit value. Use of
a 1 µF capacitor results in the current limit being reduced to
that of the next smaller device size. Use of a 10 µF capacitor
results in the current limit being increased to that of the next
larger device size for TNY275-280.
3. It provides a shutdown function. When the current into the
bypass pin exceeds 5.5 mA, the device latches off until the
BP/M voltage drops below 4.9 V, during a power down.
This can be used to provide an output overvoltage function
2
E
2/06
P Package (DIP-8C)
G Package (SMD-8C)
EN/UV
1
8
S
BP/M
2
7
S
6
S
5
S
D
4
PI-4078-080905
Figure 3. Pin Configuration.
with a Zener connected from the BP/M pin to a bias winding
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
TNY274-280
MOSFET is controlled by this pin. MOSFET switching is
terminated when a current greater than a threshold current is
drawn from this pin. Switching resumes when the current being
pulled from the pin drops to less than a threshold current. A
modulation of the threshold current reduces group pulsing. The
threshold current is between 60 µA and 115 µA.
The EN/UV 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-III detects
its absence and disables the line under-voltage function.
SOURCE (S) Pin:
This pin is internally connected to the output MOSFET source
for high voltage power return and control circuit common.
TinySwitch-III Functional
Description
TinySwitch-III combines a high voltage power MOSFET switch
with a power supply controller in one device. Unlike conventional
PWM (pulse width modulator) controllers, it uses a simple
ON/OFF control to regulate the output voltage.
The controller consists of an oscillator, enable circuit (sense and
logic), current limit state machine, 5.85 V regulator, BYPASS/
MULTI-FUNCTION pin under-voltage, overvoltage circuit, and
current limit selection circuitry, over- temperature protection,
current limit circuit, leading edge blanking, and a 700 V power
MOSFET. TinySwitch-III incorporates additional circuitry for
line under-voltage sense, auto-restart, adaptive switching cycle
on-time extension, and frequency jitter. Figure 2 shows the
functional block diagram with the most important features.
600
500
VDRAIN
400
PI-2741-041901
Oscillator
The typical oscillator frequency is internally set to an average
of 132 kHz. Two signals are generated from the oscillator: the
300
200
100
0
136 kHz
128 kHz
0
5
10
maximum duty cycle signal (DCMAX) and the clock signal that
indicates the beginning of each cycle.
The 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.
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 1.2 V. The current
through the source follower is limited to 115 µA. When the
current out of this pin exceeds the threshold current, a low
logic level (disable) is generated at the output of the enable
circuit, until the current out of this pin is reduced to less than
the threshold current. 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-III 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
enable events 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 1.2 V in the disabled
state. This improves the response time of the optocoupler that
is usually connected to this pin.
5.85 V Regulator and 6.4 V Shunt Voltage Clamp
The 5.85 V regulator charges the bypass capacitor connected
to the BYPASS pin to 5.85 V by drawing a current from the
voltage on the DRAIN pin whenever the MOSFET is off. The
BYPASS/MULTI-FUNCTION pin is the internal supply voltage
node. When the MOSFET is on, the device operates from the
energy stored in the bypass capacitor. Extremely low power
consumption of the internal circuitry allows TinySwitch-III to
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.
Time (µs)
Figure 4. Frequency Jitter.
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2/06
3
TNY274-280
In addition, there is a 6.4 V shunt regulator clamping the
BYPASS/MULTI-FUNCTION pin at 6.4 V when current
is provided to the BYPASS/MULTI-FUNCTION pin
through an external resistor. This facilitates powering of
TinySwitch-III externally through a bias winding to decrease
the no-load consumption to well below 50 mW.
BYPASS/MULTI-FUNCTION Pin Under-Voltage
The BYPASS/MULTI-FUNCTION pin under-voltage circuitry
disables the power MOSFET when the BYPASS/MULTIFUNCTION pin voltage drops below 4.9 V in steady state
operation. Once the BYPASS/MULTI-FUNCTION pin voltage
drops below 4.9 V in steady state operation, it must rise back
to 5.85 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 142 °C with 75 °C hysteresis. When
the die temperature rises above this threshold the power MOSFET
is disabled and remains disabled until the die temperature falls
by 75 °C, at which point it is re-enabled. A large hysteresis of
75 °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 (ILIMIT), 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.
V
300
PI-4098-082305
The leading edge blanking circuit inhibits the current limit
comparator for a short time (tLEB) after the power MOSFET is
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.
DRAIN
200
Auto-Restart
In the event of a fault condition such as output overload, output
short circuit, or an open loop condition, TinySwitch-III enters
into auto-restart operation. An internal counter clocked by the
oscillator is reset every time the EN/UV pin is pulled low. If the
EN/UV pin is not pulled low for 64 ms, the power MOSFET
switching is normally disabled for 2.5 seconds (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 2.5 seconds
until the line under-voltage condition ends.
Adaptive Switching Cycle On-Time Extension
Adaptive switching cycle on-time extension keeps the cycle
on until current limit is reached, instead of prematurely
terminating after the DCMAX signal goes low. This feature
reduces the minimum input voltage required to maintain
regulation, extending hold-up time and minimizing the size
of bulk capacitor required. The on-time extension is disabled
during the startup of the power supply, until the power supply
output reaches regulation.
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 autorestart, the current into the EN/UV pin must exceed 25 µA to
initiate switching of the power MOSFET. During power-up, this
is accomplished by holding the BYPASS/MULTI-FUNCTION
pin to 4.9 V while the line under-voltage condition exists. The
BYPASS/MULTI-FUNCTION pin then rises from 4.9 V to
5.85 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
2.5 seconds until the line under-voltage condition ends.
The line under-voltage circuit also detects when there is
no external resistor connected to the EN/UV pin (less than
~1 µA into the pin). In this case the line under-voltage function
is disabled.
100
0
10
TinySwitch-III Operation
V
DC-OUTPUT
5
0
2500
0
Time (ms)
Figure 5. Auto-Restart Operation.
4
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5000
TinySwitch-III 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 DCMAX limit is
reached. Since the highest current limit level and frequency of
a TinySwitch-III design are constant, the power delivered to the
TNY274-280
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-III
is appropriately chosen for the power level, the current in the
calculated inductance will ramp up to current limit before the
DCMAX limit is reached.
not to proceed with the next switching cycle. 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.
Enable Function
TinySwitch-III senses the EN/UV pin to determine whether or
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.
V
EN
In a typical implementation, the EN/UV pin is driven by an
optocoupler. The collector of the optocoupler transistor is
connected to the EN/UV pin and the emitter is connected to
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.
CLOCK
DC
MAX
I DRAIN
V DRAIN
PI-2749-082305
Figure 6. Operation at Near Maximum Loading.
ON/OFF Operation with Current Limit State Machine
The internal clock of the TinySwitch-III runs all the time. At
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, the state machine
sets the current limit to its highest value. At lighter loads, the
state machine sets the current limit to reduced values.
V
EN
V
EN
CLOCK
CLOCK
DC
DC
MAX
I DRAIN
MAX
I DRAIN
V DRAIN
V DRAIN
PI-2377-082305
PI-2667-082305
Figure 7. Operation at Moderately Heavy Loading.
Figure 8. Operation at Medium Loading.
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2/06
5
TNY274-280
V
EN
PI-2381-1030801
200
V
DC-INPUT
100
0
CLOCK
10
DC
MAX
V
5
BYPASS
0
I DRAIN
400
200
V
DRAIN
0
0
1
2
Time (ms)
V DRAIN
PI-2661-082305
200
V
DC-INPUT
100
At near maximum load, TinySwitch-III 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 ON/OFF control scheme is very fast
compared to PWM control. This provides tight regulation and
excellent transient response.
PI-2383-030801
200
V
DC-INPUT
100
0
400
300
0
0
200
0
300
400
200
DC-INPUT
V
DRAIN
100
DRAIN
0
0
1
0
2
Time (ms)
Figure 10. Power-Up with Optional External UV Resistor (4 MΩ)
Connected to EN/UV Pin.
6
V
400
BYPASS
0
V
1
Time (s)
10
200
.5
Figure 12. Normal Power-Down Timing (without UV).
100
V
DRAIN
100
0
5
V
200
PI-2395-030801
Figure 9. Operation at Very Light Load.
PI-2348-030801
Figure 11. Power-Up Without Optional External UV Resistor
Connected to EN/UV Pin.
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0
2.5
Time (s)
Figure 13. Slow Power-Down Timing with Optional External
(4 MΩ) UV Resistor Connected to EN/UV Pin.
5
TNY274-280
Power Up/Down
The TinySwitch-III requires only a 0.1 µF capacitor on the
BYPASS/MULTI-FUNCTION pin to operate with standard
current limit. Because of its small size, the time to charge this
capacitor is kept to an absolute minimum, typically 0.6 ms. The
time to charge will vary in proportion to the BYPASS/MULTIFUNCTION pin capacitor value when selecting different current
limits. Due to the high bandwidth of the ON/OFF feedback,
there is no overshoot at the power supply output. When an
external resistor (4 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 in applications with and without an external
resistor (4 MΩ) connected to the EN/UV pin.
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. TinySwitch-III accomplishes this without a
forward bias winding and its many associated components. For
applications that require very low no-load power consumption
(50 mW), a resistor from a bias winding to the BYPASS/
MULTI-FUNCTION pin can provide the power to the chip.
The minimum recommended current supplied is 1 mA. The
BYPASS/MULTI-FUNCTION pin in this case will be clamped
at 6.4 V. This method will eliminate the power draw from the
DRAIN pin, thereby reducing the no-load power consumption
and improving full-load efficiency.
Under startup and overload conditions, when the conduction time
is less than 400 ns, the device reduces the switching frequency
to maintain control of the peak drain current.
Current Limit Operation
Each switching cycle is terminated when the DRAIN current
reaches the current limit of the device. Current limit operation
provides good line ripple rejection and relatively constant power
delivery independent of input voltage.
During power-down, when an external resistor is used, the
power MOSFET will switch for 64 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.
Figure 13 illustrates a very slow power-down timing waveform
as in standby applications. The external resistor (4 MΩ) is
connected to the EN/UV pin in this case to prevent unwanted
restarts.
No bias winding is needed to provide power to the chip
because it draws the power directly from the DRAIN pin (see
BYPASS/MULTI-FUNCTION Pin Capacitor
The BYPASS/MULTI-FUNCTION pin can use a ceramic
capacitor as small as 0.1 µF for decoupling the internal power
supply of the device. A larger capacitor size can be used to adjust
the current limit. For TNY275-280, a 1 µF BP/M pin capacitor
will select a lower current limit equal to the standard current
limit of the next smaller device and a 10 µF BP/M pin capacitor
will select a higher current limit equal to the standard current
limit of the next larger device. The higher current limit level of
the TNY280 is set to 850 mA typical. The TNY274 MOSFET
does not have the capability for increased current limit so this
feature is not available in this device.
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7
TNY274-280
C5
2.2 nF
250 VAC
VR1
P6KE150A
J1
85-265
VAC
F1
3.15 A
D1
1N4007
D2
1N4007
R2
100 Ω
C1
6.8 µF
400 V
RV1
275 VAC
C2
22 µF
400 V
D4
1N4007
C4
10 nF
1 kV
R1
1 kΩ
8
C10
1000 µF
25 V
6
3
R7
4 20 Ω
2
D6
UF4003
5
C6
1 µF
60 V
R3
47 Ω
1/8 W
C7 is configurable to adjust
U1 current limit, see circuit
description
D
S
TinySwitch-III
U1
TNY278P
+12 V, 1 A
J3
C11
100 µF
25 V J4
RTN
VR2
1N5255B
28 V
L1
1 mH
*R5 and R8 are optional
components
†
L2
Ferrite Bead
3.5 × 7.6 mm
D7
BYV28-200
1
D5
1N4007GP
R5*
3.6 MΩ
J2
D3
1N4007
NC
T1
R8*
21 kΩ
1%
EN/UV
VR3
BZX79-C11
11 V
R6
390 Ω
1/8 W
U2
PC817A
BP/M
S
C7 †
100 nF
50 V
R4
2 kΩ
1/8 W
PI-4244-021406
Figure 14. TNY278P, 12 V, 1 A Universal Input Power Supply.
Applications Example
The circuit shown in Figure 14 is a low cost, high efficiency,
flyback power supply designed for 12 V, 1 A output from
universal input using the TNY278.
The supply features under-voltage lockout, primary sensed
output overvoltage latching shutdown protection, high
efficiency (>80%), and very low no-load consumption
(<50 mW at 265 VAC). Output regulation is accomplished using
a simple zener reference and optocoupler feedback.
The rectified and filtered input voltage is applied to the primary
winding of T1. The other side of the transformer primary is
driven by the integrated MOSFET in U1. Diode D5, C2, R1,
R2, and VR1 comprise the clamp circuit, limiting the leakage
inductance turn-off voltage spike on the DRAIN pin to a safe
value. The use of a combination a Zener clamp and parallel
RC optimizes both EMI and energy efficiency. Resistor R2
allows the use of a slow recovery, low cost, rectifier diode by
limiting the reverse current through D5. The selection of a
slow diode also improves efficiency and conducted EMI but
should be a glass passivated type, with a specified recovery
time of ≤2 µs.
The output voltage is regulated by the Zener diode VR3. When
the output voltage exceeds the sum of the Zener and optocoupler
8
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2/06
LED forward drop, current will flow in the optocoupler LED.
This will cause the transistor of the optocoupler to sink current.
When this current exceeds the ENABLE pin threshold current
the next switching cycle is inhibited. When the output voltage
falls below the feedback threshold, a conduction cycle is allowed
to occur and, by adjusting the number of enabled cycles, output
regulation is maintained. As the load reduces, the number of
enabled cycles decreases, lowering the effective switching
frequency and scaling switching losses with load. This provides
almost constant efficiency down to very light loads, ideal for
meeting energy efficiency requirements.
As the TinySwitch-III devices are completely self-powered,
there is no requirement for an auxiliary or bias winding on the
transformer. However by adding a bias winding, the output
overvoltage protection feature can be configured, protecting
the load against open feedback loop faults.
When an overvoltage condition occurs, such that bias voltage
exceeds the sum of VR2 and the BYPASS/MULTIFUNCTION
(BP/M) pin voltage (28 V+5.85 V), current begins to flow into the
BP/M pin. When this current exceeds 5 mA the internal latching
shutdown circuit in TinySwitch-III is activated. This condition
is reset when the BP/M pin voltage drops below 2.6 V after
removal of the AC input. In the example shown, on opening
the loop, the OVP trips at an output of 17 V.
TNY274-280
For lower no-load input power consumption, the bias winding
may also be used to supply the TinySwitch-III device. Resistor
R8 feeds current into the BP/M pin, inhibiting the internal high
voltage current source that normally maintains the BP/M pin
capacitor voltage (C7) during the internal MOSFET off time.
This reduces the no-load consumption of this design from
140 mW to 40 mW at 265 VAC.
Under-voltage lockout is configured by R5 connected between
the DC bus and EN/UV pin of U1. When present, switching
is inhibited until the current in the EN/UV pin exceeds 25 µA.
This allows the startup voltage to be programmed within the
normal operating input voltage range, preventing glitching of
the output under abnormal low voltage conditions and also on
removal of the AC input.
In addition to the simple input pi filter (C1, L1, C2) for
differential mode EMI, this design makes use of E-Shield™
shielding techniques in the transformer to reduce common
mode EMI displacement currents, and R2 and C4 as a damping
network to reduce high frequency transformer ringing. These
techniques, combined with the frequency jitter of TNY278,
give excellent conducted and radiated EMI performance with
this design achieving >12 dBµV of margin to EN55022 Class
B conducted EMI limits.
For design flexibility the value of C7 can be selected to pick one
of the 3 current limits options in U1. This allows the designer
to select the current limit appropriate for the application.
•
•
•
Standard current limit (ILIMIT) is selected with a 0.1 µF BP/M
pin capacitor and is the normal choice for typical enclosed
adapter applications.
When a 1 µF BP/M pin capacitor is used, the current
limit is reduced (ILIMITred or ILIMIT-1) offering reduced RMS
device currents and therefore improved efficiency, but at
the expense of maximum power capability. This is ideal
for thermally challenging designs where dissipation must
be minimized.
When a 10 µF BP/M pin capacitor is used, the current
limit is increased (ILIMITinc or ILIMIT+1), extending the power
capability for applications requiring higher peak power or
continuous power where the thermal conditions allow.
Further flexibility comes from the current limits between adjacent
TinySwitch-III family members being compatible. The reduced
current limit of a given device is equal to the standard current
limit of the next smaller device and the increased current limit is
equal to the standard current limit of the next larger device.
Key Application Considerations
TinySwitch-lll Design Considerations
Output Power Table
The data sheet output power table (Table 1) represents the
minimum practical continuous output power level that can be
obtained under the following assumed conditions:
1. The minimum DC input voltage is 100 V or higher for
85 VAC input, or 220 V or higher for 230 VAC input or
115 VAC with a voltage doubler. The value of the input
capacitance should be sized to meet these criteria for AC
input designs.
2. Efficiency of 75%.
3. Minimum data sheet value of I2f.
4. Transformer primary inductance tolerance of ±10%.
5. Reflected output voltage (VOR) of 135 V.
6. Voltage only output of 12 V with a fast PN rectifier diode.
7. Continuous conduction mode operation with transient KP*
value of 0.25.
8. Increased current limit is selected for peak and open frame
power columns and standard current limit for adapter
columns.
9. The part is board mounted with SOURCE pins soldered to
a sufficient area of copper and/or a heatsink is used to keep
the SOURCE pin temperature at or below 110 °C.
10. Ambient temperature of 50 °C for open frame designs and
40 °C for sealed adapters.
*Below a value of 1, KP is the ratio of ripple to peak primary
current. To prevent reduced power capability due to premature
termination of switching cycles a transient KP limit of ≥0.25
is recommended. This prevents the initial current limit (IINIT)
from being exceeded at MOSFET turn on.
For reference, Table 2 provides the minimum practical power
delivered from each family member at the three selectable current
limit values. This assumes open frame operation (not thermally
limited) and otherwise the same conditions as listed above.
These numbers are useful to identify the correct current limit
to select for a given device and output power requirement.
Overvoltage Protection
The output overvoltage protection provided by TinySwitch-III
uses an internal latch that is triggered by a threshold current
of approximately 5.5 mA into the BP/M pin. In addition to an
internal filter, the BP/M pin capacitor forms an external filter
providing noise immunity from inadvertent triggering. For the
bypass capacitor to be effective as a high frequency filter, the
capacitor should be located as close as possible to the SOURCE
and BP/M pins of the device.
E
2/06
9
TNY274-280
OUTPUT POWER TABLE
PRODUCT
85-265 VAC
230 VAC ±15%
ILIMIT-1
ILIMIT
ILIMIT+1
ILIMIT-1
ILIMIT
ILIMIT+1
TNY274 P or G
9
10.9
9.1
7.1
8.5
7.1
TNY275 P or G
10.8
12
15.1
8.4
9.3
11.8
TNY276 P or G
11.8
15.3
19.4
9.2
11.9
15.1
TNY277 P or G
15.1
19.6
23.7
11.8
15.3
18.5
TNY278 P or G
19.4
24
28
15.1
18.6
21.8
TNY279 P or G
23.7
28.4
32.2
18.5
22
25.2
TNY280 P or G
28
32.7
36.6
21.8
25.4
28.5
Table 2. Minimum Practical Power at Three Selectable Current Limit Levels.
For best performance of the OVP function, it is recommended
that a relatively high bias winding voltage is used, in the range of
15 V-30 V. This minimizes the error voltage on the bias winding
due to leakage inductance and also ensures adequate voltage
during no-load operation from which to supply the BP/M pin
for reduced no-load consumption.
practically eliminates audible noise. Vacuum impregnation
of the transformer should not be used due to the high primary
capacitance and increased losses that result. Higher flux densities
are possible, however careful evaluation of the audible noise
performance should be made using production transformer
samples before approving the design.
Selecting the Zener diode voltage to be approximately 6 V
above the bias winding voltage (28 V for 22 V bias winding)
gives good OVP performance for most designs, but can be
adjusted to compensate for variations in leakage inductance.
Adding additional filtering can be achieved by inserting a low
value (10 Ω to 47 Ω) resistor in series with the bias winding
diode and/or the OVP Zener as shown by R7 and R3 in
Figure 14. The resistor in series with the OVP Zener also limits
the maximum current into the BP/M pin.
Ceramic capacitors that use dielectrics such as Z5U, when used
in clamp circuits, may also generate audio noise. If this is the
case, try replacing them with a capacitor having a different
dielectric or construction, for example a film type.
Reducing No-load Consumption
As TinySwitch-III is self-powered from the BP/M pin capacitor,
there is no need for an auxillary or bias winding to be provided
on the transformer for this purpose. Typical no-load consumption
when self-powered is <150 mW at 265 VAC input. The addition
of a bias winding can reduce this down to <50 mW by supplying
the TinySwitch-III from the lower bias voltage and inhibiting the
internal high voltage current source. To achieve this, select the
value of the resistor (R8 in Figure 14) to provide the data sheet
DRAIN supply current. In practice, due to the reduction of the
bias voltage at low load, start with a value equal to 40% greater
than the data sheet maximum current, and then increase the value
of the resistor to give the lowest no-load consumption.
Audible Noise
The cycle skipping mode of operation used in TinySwitch-III
can generate audio frequency components in the transformer.
To limit this audible noise generation the transformer should
be designed such that the peak core flux density is below
3000 Gauss (300 mT). Following this guideline and using the
standard transformer production technique of dip varnishing
10
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2/06
TinySwitch-lll Layout Considerations
Layout
See Figure 15 for a recommended circuit board layout for
TinySwitch-III.
Single Point Grounding
Use a single point ground connection from the input filter capacitor
to the area of copper connected to the SOURCE pins.
Bypass Capacitor (CBP)
The BP/M pin capacitor should be located as near as possible
to the BP/M and SOURCE pins.
Primary Loop Area
The area of the primary loop that connects the input filter
capacitor, transformer primary and TinySwitch-III 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 or a Zener
(~200 V) and diode clamp across the primary winding. In all
cases, to minimize EMI, care should be taken to minimize the
circuit path from the clamp components to the transformer and
TinySwitch-III.
TNY274-280
TOP VIEW
Input Filter
Capacitor
Y1Capacitor
+
HV DC
INPUT
-
T
r
a
n
s
f
o
r
m
e
r
S S S S
CBP
TinySwitch-III
EN/UV BP/M D
Output Filter
Capacitor
Optocoupler
Maximize hatched copper
areas (
) for optimum
heatsinking
-
DC
OUT
+
PI-4278-013006
Figure 15. Recommended Circuit Board Layout for TinySwitch-III with Under-Voltage Lock Out Resistor.
Thermal Considerations
The four SOURCE pins are internally connected to the IC lead
frame and provide the main path to remove heat from the device.
Therefore all the SOURCE pins should be connected to a copper
area underneath the TinySwitch-III to act not only as a single
point ground, but also as a heatsink. As this area is connected
to the quiet source node, this area should be maximized for
good heatsinking. Similarly for axial output diodes, maximize
the PCB area connected to the cathode.
Y-Capacitor
The placement of the Y-capacitor should be directly from the
primary input filter capacitor positive terminal to the common/
return terminal of the transformer secondary. Such a placement
will route high magnitude common mode surge currents away
from the TinySwitch-III device. Note – if an input π (C, L, C)
EMI filter is used then the inductor in the filter should be placed
between the negative terminals of the input filter capacitors.
Optocoupler
Place the optocoupler physically close to the TinySwitch-III
to minimizing the primary-side trace lengths. Keep the high
current, high voltage drain and clamp traces away from the
optocoupler to prevent noise pick up.
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. In addition, sufficient copper
area should be provided at the anode and cathode terminals
of the diode for heatsinking. A larger area is preferred at the
quiet cathode terminal. A large anode area can increase high
frequency radiated EMI.
E
2/06
11
TNY274-280
Quick Design Checklist
As with any power supply design, all TinySwitch-III designs
should be verified on the bench to make sure that component
specifications are not exceeded under worst case conditions. The
following minimum set of tests is strongly recommended:
1. Maximum drain voltage – Verify that VDS does not exceed
650 V at highest input voltage and peak (overload) output
power. The 50 V margin to the 700 V BVDSS specification
gives margin for design variation.
2. Maximum drain current – At maximum ambient temperature,
maximum input voltage and peak output (overload) power,
verify drain current waveforms for any signs of transformer
saturation and excessive leading edge current spikes at
12
E
2/06
startup. Repeat under steady state conditions and verify that
the leading edge current spike event is below ILIMIT(Min) at the
end of the tLEB(Min). Under all conditions, the maximum drain
current should be below the specified absolute maximum
ratings.
3. Thermal Check – At specified maximum output power,
minimum input voltage and maximum ambient temperature,
verify that the temperature specifications are not exceeded
for TinySwitch-III, transformer, output diode, and output
capacitors. Enough thermal margin should be allowed for
part-to-part variation of the RDS(ON) of TinySwitch-III as
specified in the data sheet. Under low line, maximum power,
a maximum TinySwitch-III SOURCE pin temperature of
110 °C is recommended to allow for these variations.
TNY274-280
ABSOLUTE MAXIMUM RATINGS(1,5)
DRAIN Voltage ................................................-0.3 V to 700 V
DRAIN Peak Current: TNY274.......................400 (750) mA(2)
TNY275.....................560 (1050) mA(2)
TNY276.....................720 (1350) mA(2)
TNY277.....................880 (1650) mA(2)
TNY278...................1040 (1950) mA(2)
TNY279 ................. 1200 (2250) mA(2)
TNY280 ................. 1360 (2550) mA(2)
EN/UV Voltage ................................................... -0.3 V to 9 V
EN/UV Current ........................................................... 100 mA
BP/M Voltage .................................................. ....-0.3 V to 9 V
Storage Temperature ......................................-65 °C to 150 °C
Operating Junction Temperature(3) .................-40 °C to 150 °C
Lead Temperature(4) ....................................................... 260 °C
Notes:
1. All voltages referenced to SOURCE, TA = 25 °C.
2. The higher peak DRAIN current is allowed while the
DRAIN voltage is simultaneously less than 400 V.
3. Normally limited by internal circuitry.
4. 1/16 in. from case for 5 seconds.
5. 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.
THERMAL IMPEDANCE
Notes:
Thermal Impedance: P or G Package:
1. Measured on the SOURCE pin close to plastic interface.
(θJA) ........................... 70 °C/W(2); 60 °C/W(3)
2. Soldered to 0.36 sq. in. (232 mm2), 2 oz. (610 g/m2) copper clad.
(θJC)(1) ............................................... 11 °C/W
3. Soldered to 1 sq. in. (645 mm2), 2 oz. (610 g/m2) copper clad.
Conditions
Parameter
Symbol
SOURCE = 0 V; TJ = -40 to 125 °C
See Figure 16
(Unless Otherwise Specified)
Min
Typ
Max
124
132
140
Units
CONTROL FUNCTIONS
Output Frequency
in Standard Mode
Maximum Duty
Cycle
fOSC
DCMAX
EN/UV Pin Upper
Turnoff Threshold
Current
IDIS
EN/UV Pin
Voltage
VEN
IS1
DRAIN Supply
Current
IS2
Average
TJ = 25 °C
See Figure 4
Peak-Peak Jitter
S1 Open
8
62
65
-150
-115
-90
IEN/UV = 25 µA
1.8
2.2
2.6
IEN/UV = -25 µA
0.8
1.2
1.6
EN/UV Current > IDIS (MOSFET Not
Switching) See Note A
EN/UV Open
(MOSFET
Switching at fOSC)
See Note B
kHz
%
µA
V
290
µA
TNY274
275
360
TNY275
295
400
TNY276
310
430
TNY277
365
460
TNY278
445
540
TNY279
510
640
TNY280
630
760
µA
E
2/06
13
TNY274-280
Conditions
Parameter
Symbol
SOURCE = 0 V; TJ = -40 to 125 °C
See Figure 16
(Unless Otherwise Specified)
Min
Typ
Max
Units
TNY274
-6
-3.8
-1.8
TNY275-279
-8.3
-5.4
-2.5
TNY280
-9.7
-6.8
-3.9
TNY274
-4.1
-2.3
-1
TNY275-279
-5
-3.5
-1.5
TNY280
-6.6
-4.6
-2.1
5.6
5.85
6.15
V
0.80
0.95
1.20
V
IBP = 2 mA
6.0
6.4
6.7
V
TJ = 25 °C
22.5
25
27.5
µA
CONTROL FUNCTIONS (cont.)
ICH1
BP/M Pin Charge
Current
ICH2
BP/M Pin Voltage
VBP/M
BP/M Pin Voltage
VBP/MH
Hysteresis
BP/M Pin Shunt
VSHUNT
Voltage
EN/UV Pin Line
ILUV
Under-Voltage
Threshold
CIRCUIT PROTECTION
Standard Current
Limit (BP/M
Capacitor =
0.1 µF)
See Note D
Reduced Current
Limit (BP/M
Capacitor = 1 µF)
14
E
2/06
ILIMIT
ILIMITred
VBP/M = 0 V,
TJ = 25 °C
See Note C, D
VBP/M = 4 V,
TJ = 25 °C
See Note C, D
See Note C
TNY274
TJ = 25 °C
di/dt = 50 mA/µs
See Note E
233
250
267
TNY275
TJ = 25 °C
di/dt = 55 mA/µs
See Note E
256
275
294
TNY276
TJ = 25 °C
di/dt = 70 mA/µs
See Note E
326
350
374
TNY277
TJ = 25 °C
di/dt = 90 mA/µs
See Note E
419
450
481
TNY278
TJ = 25 °C
di/dt = 110 mA/µs
See Note E
512
550
588
TNY279
TJ = 25 °C
di/dt = 130 mA/µs
See Note E
605
650
695
TNY280
TJ = 25 °C
di/dt = 150 mA/µs
See Note E
698
750
802
TNY274
TJ = 25 °C
di/dt = 50 mA/µs
See Note E
196
210
233
TNY275
TJ = 25 °C
di/dt = 55 mA/µs
See Note E
233
mA
mA
mA
250
277
TNY274-280
Conditions
Parameter
Symbol
SOURCE = 0 V; TJ = -40 to 125 °C
See Figure 16
(Unless Otherwise Specified)
Min
Typ
Max
Units
CIRCUIT PROTECTION (cont.)
Reduced Current
Limit (BP/M
Capacitor = 1 µF)
See Note D
Increased Current
Limit (BP/M
Capacitor = 10 µF)
See Note D
ILIMITred
ILIMITinc
TNY276
TJ = 25 °C
di/dt = 70 mA/µs
See Note E
256
275
305
TNY277
TJ = 25 °C
di/dt = 90 mA/µs
See Note E
326
350
388
TNY278
TJ = 25 °C
di/dt = 110 mA/µs
See Note E
419
450
499
TNY279
TJ = 25 °C
di/dt = 130 mA/µs
See Note E
512
550
610
TNY280
TJ = 25 °C
di/dt = 150 mA/µs
See Note E
605
650
721
TNY274
TJ = 25 °C
di/dt = 50 mA/µs
See Note E, F
196
210
233
TNY275
TJ = 25 °C
di/dt = 55 mA/µs
See Note E
326
350
388
TNY276
TJ = 25 °C
di/dt = 70 mA/µs
See Note E
419
450
499
TNY277
TJ = 25 °C
di/dt = 90 mA/µs
See Note E
512
550
610
TNY278
TJ = 25 °C
di/dt = 110 mA/µs
See Note E
605
650
721
TNY279
TJ = 25 °C
di/dt = 130 mA/µs
See Note E
698
750
833
TNY280
TJ = 25 °C
di/dt = 150 mA/µs
See Note E
791
850
943
Standard
Current Limit
0.9 ×
I2f
I2f
1.12 ×
I2f
Reduced or
Increased
Current Limit
0.9 ×
I2f
I2f
1.16 ×
I2f
I2f = ILIMIT(TYP)2 ×
fOSC(TYP)
Power Coefficient
I2f
Initial Current Limit
IINIT
See Figure 19
TJ = 25 °C, See Note G
0.75 ×
ILIMIT(MIN)
Leading Edge
Blanking Time
tLEB
TJ = 25 °C
See Note G
170
Current Limit
Delay
tILD
TJ = 25 °C
See Note G, H
Thermal Shutdown
Temperature
TSD
135
mA
mA
A2Hz
mA
215
ns
150
ns
142
150
°C
E
2/06
15
TNY274-280
Conditions
Parameter
Symbol
SOURCE = 0 V; TJ = -40 to 125 °C
See Figure 16
(Unless Otherwise Specified)
Min
Typ
Max
Units
CIRCUIT PROTECTION (cont.)
Thermal Shutdown Hysteresis
TSDH
BP/M Pin Shutdown Threshold
Current
ISD
75
°C
4
5.5
7.5
mA
1.6
2.6
3.6
V
TJ = 25 °C
28
32
TJ = 100 °C
42
48
TJ = 25 °C
19
22
TJ = 100 °C
29
33
TJ = 25 °C
14
16
TJ = 100 °C
21
24
TJ = 25 °C
7.8
9.0
TJ = 100 °C
11.7
13.5
TJ = 25 °C
5.2
6.0
TJ = 100 °C
7.8
9.0
TJ = 25 °C
3.9
4.5
TJ = 100 °C
5.8
6.7
TJ = 25 °C
2.6
3.0
TJ = 100 °C
3.9
4.5
BP/M Pin PowerUp Reset Thresh- VBP/M(RESET)
old Voltage
OUTPUT
TNY274
ID = 25 mA
TNY275
ID = 28 mA
TNY276
ID = 35 mA
ON-State
Resistance
RDS(ON)
TNY277
ID = 45 mA
TNY278
ID = 55 mA
TNY279
ID = 65 mA
TNY280
ID = 75 mA
OFF-State Drain
Leakage Current
IDSS1
IDSS2
Breakdown
Voltage
DRAIN Supply
Voltage
16
E
2/06
BVDSS
VBP/M = 6.2 V
VEN/UV = 0 V
VDS = 560 V
TJ = 125 °C
See Note I
TNY274-276
50
TNY277-278
100
TNY279-280
200
VBP/M = 6.2 V
VEN/UV = 0 V
VDS = 375 V,
TJ = 50 °C
See Note G, I
VBP = 6.2 V, VEN/UV = 0 V,
See Note J, TJ = 25 °C
Ω
µA
15
700
V
50
V
TNY274-280
Conditions
Parameter
Symbol
SOURCE = 0 V; TJ = -40 to 125 °C
See Figure 16
(Unless Otherwise Specified)
Min
Typ
Max
Units
OUTPUT (cont.)
Auto-Restart
ON-Time at fOSC
Auto-Restart
Duty Cycle
tAR
TJ = 25 °C
See Note K
64
ms
DCAR
TJ = 25 °C
3
%
NOTES:
A. IS1 is an accurate estimate of device controller current consumption at no-load, since operating frequency is so
low under these conditions. Total device consumption at no-load is the sum of IS1 and IDSS2.
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 BP/M pin current at 6.1 V.
C. BP/M pin is not intended for sourcing supply current to external circuitry.
D. To ensure correct current limit it is recommended that nominal 0.1 µF / 1 µF / 10 µF capacitors are used. In
addition, the BP/M capacitor value tolerance should be equal or better than indicated below across the ambient
temperature range of the target application. The minimum and maximum capacitor values are guaranteed by
characterization.
Nominal BP/M
Pin Cap Value
Tolerance Relative to Nominal
Capacitor Value
Min
MAX
0.1 µF
-60%
+100%
1 µF
-50%
+100%
10 µF
-50%
NA
E. For current limit at other di/dt values, refer to Figure 23.
F. TNY274 does not set an increased current limit value, but with a 10 µF BP/M pin capacitor the current limit is the
same as with a 1 µF BP/M pin capacitor (reduced current limit value).
G. This parameter is derived from characterization.
H. This parameter is derived from the change in current limit measured at 1X and 4X of the di/dt shown in the ILIMIT
specification.
I. IDSS1 is the worst case OFF state leakage specification at 80% of BVDSS and maximum operating junction
temperature. IDSS2 is a typical specification under worst case application conditions (rectified 265 VAC) for no-load
consumption calculations.
J. Breakdown voltage may be checked against minimum BVDSS specification by ramping the DRAIN pin voltage up
to but not exceeding minimum BVDSS.
K. Auto-restart on time has the same temperature characteristics as the oscillator (inversely proportional to
frequency).
E
2/06
17
TNY274-280
470 Ω
5W
S2
470 Ω
S
D
S1
S
S
S
2 MΩ
50 V
BP/M
EN/UV
10 V
0.1 µF
150 V
NOTE: This test circuit is not applicable for current limit or output characteristic measurements.
PI-4079-080905
Figure 16. General Test Circuit.
DCMAX
(internal signal)
tP
EN/UV
tEN/UV
VDRAIN
tP =
1
fOSC
PI-2364-012699
Figure 18. Output Enable Timing.
PI-4279-013006
Figure 17. Duty Cycle Measurement.
0.8
Figure 19. Current Limit Envelope.
18
E
2/06
TNY274-280
Typical Performance Characteristics
1.0
PI-4280-012306
1.2
Output Frequency
(Normalized to 25 °C)
PI-2213-012301
Breakdown Voltage
(Normalized to 25 °C)
1.1
1.0
0.8
0.6
0.4
0.2
0
0.9
-50 -25
0
25
50
-50
75 100 125 150
0.8
0.6
0.4
0.2
0
100
1.0
0.8
TNY274
TNY275
TNY276
TNY277
TNY278
TNY279
TNY280
0.6
0.4
0.2
1
2
3
4
100
TCASE=25 °C
TCASE=100 °C
1000
PI-4083-082305
Scaling Factors:
TNY274 1.0
TNY275 1.5
TNY276 2.0
TNY277 3.5
TNY278 5.5
TNY279 7.3
TNY280 11
Figure 23. Current Limit vs. di/dt.
Drain Capacitance (pF)
PI-4082-082305
Drain Current (mA)
Note: For the
normalized current
limit value, use the
typical current limit
specified for the
appropriate BP/M
capacitor.
Normalized di/dt
300
50
Normalized
di/dt = 1
50 mA/µs
55 mA/µs
70 mA/µs
90 mA/µs
110 mA/µs
130 mA/µs
150 mA/µs
0
150
Figure 22. Standard Current Limit vs. Temperature.
150
100 125
1.2
Temperature (°C)
200
75
PI-4081-082305
1
250
50
1.4
Normalized Current Limit
PI-4102-010906
Standard Current Limit
(Normalized to 25 °C)
1.2
50
25
Figure 21. Frequency vs. Temperature.
Figure 20. Breakdown vs. Temperature.
0
0
Junction Temperature (°C)
Junction Temperature (°C)
-50
-25
100
Scaling Factors:
TNY274 1.0
TNY275 1.5
TNY276 2.0
TNY277 3.5
TNY278 5.5
TNY279 7.3
TNY280 11
10
1
0
0
2
4
6
DRAIN Voltage (V)
Figure 24. Output Characteristic.
8
10
0
100
200
300
400
500
600
Drain Voltage (V)
Figure 25. COSS vs. Drain Voltage.
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2/06
19
TNY274-280
Typical Performance Characteristics (cont.)
30
20
10
0
200
400
DRAIN Voltage (V)
Figure 26. Drain Capacitance Power.
E
2/06
PI-4281-012306
1.0
0.8
0.6
0.4
0.2
0
0
20
1.2
Under-Voltage Threshold
(Normalized to 25 °C)
Scaling Factors:
TNY274 1.0
TNY275 1.5
TNY276 2.0
TNY277 3.5
TNY278 5.5
TNY279 7.3
TNY280 11
40
Power (mW)
PI-4084-082305
50
600
-50
-25
0
25
50
75
100 125
Junction Temperature (°C)
Figure 27. Under-Voltage Threshold vs. Temperature.
TNY274-280
PART ORDERING INFORMATION
TinySwitch Product Family
Series Number
Package Identifier
G
Plastic Surface Mount SMD-8C
P
Plastic DIP-8C
Lead Finish
N
Pure Matte Tin (Pb-Free)
Tape & Reel and Other Options
Blank Standard Configurations
TNY 278 G N - TL
TL
Tape & Reel, 1000 pcs min./mult., G Package only
DIP-8C
-E-
⊕D S
.004 (.10)
.240 (6.10)
.260 (6.60)
Pin 1
-D-
.367 (9.32)
.387 (9.83)
.057 (1.45)
.068 (1.73)
(NOTE 6)
.125 (3.18)
.145 (3.68)
-T-
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-clockwise to Pin 8 when viewed from the top. The notch and/or
dimple are aids in locating Pin 1. Pin 3 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.
.015 (.38)
MINIMUM
SEATING
PLANE
.120 (3.05)
.140 (3.56)
.100 (2.54) BSC
.014 (.36)
.022 (.56)
.048 (1.22)
.053 (1.35)
⊕T E D
.137 (3.48)
MINIMUM
S .010 (.25) M
.008 (.20)
.015 (.38)
.300 (7.62) BSC
(NOTE 7)
.300 (7.62)
.390 (9.91)
P08C
PI-3933-100504
E
2/06
21
TNY274-280
SMD-8C
⊕ D S .004 (.10)
.046 .060
.060 .046
-E-
.080
.086
.186
.372 (9.45)
.388 (9.86)
⊕ E S .010 (.25)
.240 (6.10)
.260 (6.60)
Pin 1
.286
Pin 1
.100 (2.54) (BSC)
.137 (3.48)
MINIMUM
Solder Pad Dimensions
.367 (9.32)
.387 (9.83)
-D-
.057 (1.45)
.068 (1.73)
(NOTE 5)
.125 (3.18)
.145 (3.68)
.032 (.81)
.037 (.94)
.420
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-clockwise to Pin 8 when viewed
from the top. Pin 3 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.
.048 (1.22)
.053 (1.35)
.004 (.10)
.009 (.23)
.004 (.10)
.012 (.30)
.036 (0.91)
.044 (1.12)
0°- 8°
G08C
PI-4015-013106
22
E
2/06
TNY274-280
E
2/06
23
TNY274-280
Revision Notes
Date
D
Release final data sheet.
1/06
E
Corrected figure numbers and references.
2/06
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.
The PI logo, TOPSwitch, TinySwitch, LinkSwitch, DPA-Switch, EcoSmart, Clampless, E-Shield, Filterfuse,
PI Expert and PI FACTS are trademarks of Power Integrations, Inc. Other trademarks are property of their respective companies.
©Copyright 2006, Power Integrations, Inc.
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24
E
2/06
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