Off-line Switcher. TNY267PN Datasheet
This product is not recommended for new designs.
Enhanced, Energy Efficient, Low Power
TinySwitch-II Features Reduce System Cost
• Fully integrated auto-restart for short circuit and open loop fault
protection – saves external component costs
• Built-in circuitry practically eliminates audible noise with ordinary
• Programmable line undervoltage detect feature prevents power
on/off glitches – saves external components
• Frequency jittering dramatically reduces EMI (~10 dB)
– minimizes EMI filter component costs
• 132 kHz operation reduces transformer size – allows use of
EF12.6 or EE13 cores for low cost and small size
• Very tight tolerances and negligible temperature variation on key
parameters eases design and lowers cost
• 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 manufacturing
EcoSmart™– Extremely Energy Efficient
• No load consumption <50 mW with bias winding and
<250 mW without bias winding at 265 VAC input
• Meets California Energy Commission (CEC), Energy Star, and
• 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 safety
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 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.
Figure 1. Typical Standby Application.
Output Power Table
230 VAC ± 15%
Table 1. Output Power Table.
1. Minimum continuous power in a typical non-ventilated enclosed adapter
measured at 50 °C ambient.
2. Minimum practical continuous power in an open frame design with adequate
heat sinking, measured at 50 °C ambient (See Key Applications
3. Packages: P: DIP-8B, G: SMD-8B. Please see Part Ordering Information.
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
undervoltage 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.
This Product is Covered by Patents and/or Pending Patent Applications.
1.0 V + VT
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 µF external bypass capacitor for the
internally generated 5.8 V supply.
ENABLE/UNDERVOLTAGE (EN/UV) Pin:
This pin has dual functions: enable input and line undervoltage
sense. During normal operation, switching of the power
MOSFET is controlled by this pin. MOSFET switching is
terminated when a current greater than 240 µA is drawn from
this pin. This pin also senses line undervoltage 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
SOURCE (S) Pin:
Control circuit common, internally connected to output
P Package (DIP-8B)
G Package (SMD-8B)
8 S (HV RTN)
7 S (HV RTN)
Figure 3. Pin Configuration.
SOURCE (HV RTN) Pin:
Output MOSFET source connection for high voltage return.
Rev. J 08/16
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 undervoltage circuit, over-
temperature protection, current limit circuit, leading edge
blanking and a 700 V power MOSFET. TinySwitch-II
incorporates additional circuitry for line undervoltage sense,
auto-restart and frequency jitter. Figure 2 shows the functional
block diagram with the most important features.
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 (DCMAX) and the clock signal that
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 µA. When the
current out of this pin exceeds 240 µA, a low logic level
(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
Figure 4. Frequency Jitter.
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
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 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
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.
BYPASS Pin Undervoltage
The BYPASS pin undervoltage 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 70 °C (typical) is provided to prevent
overheating of the PC board due to a continuous fault
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
Rev. J 08/16