Off-line Switcher. TNY256Y Datasheet
Low Power Off-line Switcher
|Total Page||20 Pages|
Energy Efficient, Low Power Off-line Switcher
TinySwitch Plus Features
• Extended power range
• Fully integrated auto-restart reduces short circuit current
• Line under-voltage sense eliminates turn-off glitches
• Frequency jittering dramatically reduces EMI (5 to 10 dB)
• TO-220 package option
Lowest Cost, Low Power Switcher Solution
• Lower cost than RCC, discrete PWM and other
• Cost effective replacement for bulky linear adapters
• Lowest component count
• Simple ON/OFF control – no loop compensation components
• No bias winding – simpler, lower cost transformer
• Designed to work with low cost external components
Extremely Energy Efficient
• Consumes only 30/60 mW at 115/230 VAC with no load
• Meets Blue Angel, Energy Star, Energy 2000 and
200mW European cell phone requirements for standby
• Saves $1 to $4 per year in energy costs (at $0.12/kWHr)
compared to bulky linear adapters
• Ideal for cellular phone chargers and adapters
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
The TNY256 extends the power range of the TinySwitch family
of energy efficient, low power off-line switchers. TinySwitch
devices use a breakthrough design to provide the lowest cost,
high efficiency, off-line switching solution for low power
applications. They integrate a 700 V power MOSFET, oscillator,
high voltage switched current source, current limit and thermal
shutdown circuitry into a single, monolithic device. The
devices start-up and operate on power derived from the DRAIN
voltage, eliminating the need for a transformer bias winding and
associated circuitry. TinySwitch's low operating current allows
power supply no-load consumption to be kept under 100 mW,
even at 265 VAC input.
HV DC Input
Figure 1. Typical Standby Application.
OUTPUT POWER CAPABILITY*
230 VAC or
Table 1. * The low end of the power ranges shown represent enclosed
adapters with minimal heat sinking whereas, the high end of the power
ranges represent open frame power supplies with adequate heat
sinking, both measured at an ambient of 50 oC. Please refer to the Key
Application Considerations section for more details.
The TinySwitch Plus incorporates auto-restart, line under-voltage
sense, and frequency jittering features. The auto-restart circuit
safely limits output power during fault conditions such as output
short or open loop. The auto-restart circuit is fully integrated and
does not require external timing components. The line under-
voltage sense threshold can be externally programmed using a line
sense resistor. During start-up, this feature keeps the TNY256 off
until the input line voltage reaches the under-voltage threshold.
When the input line voltage is removed, the line under-voltage
circuit prevents auto-restart attempts after the output goes out of
regulation. This eliminates power down glitches caused by the
slow discharge of input storage capacitors present in applications
such as standby supplies. A single resistor is used to implement
this feature, eliminating what normally takes five to six components.
The line sense resistor is optional. The TNY256 operating frequency
of 130 kHz is jittered (frequency modulated) to reduce both quasi-
peak and average EMI, minimizing filtering costs.
1.5 V + VTH
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/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 50 µA is drawn out of
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, TNY256
detects this and disables the line under-voltage function.
SOURCE (S) Pin:
Power MOSFET source connection. Primary return.
Connected to SOURCE Pin
Y Package (TO-220-7B)
P Package (DIP-8)
G Package (SMD-8)
Figure 3. Pin Configuration.
NO CONNECT (N) Pin
|Features||Datasheet pdf TNY256 TinySwitch® Plus Energy Efficien t, Low Power Off-line Switcher ® Pro duct Highlights TinySwitch Plus Feature s • Extended power range • Fully in tegrated auto-restart reduces short cir cuit current • Line under-voltage sen se eliminates turn-off glitches • Fre quency jittering dramatically reduces E MI (5 to 10 dB) • TO-220 package opti on Lowest Cost, Low Power Switcher Solu tion • Lower cost than RCC, discrete PWM and other integrated/hybrid solutio ns • Cost effective replacement for b ulky linear adapters • Lowest compone nt count • Simple ON/OFF control – no loop compensation components • No bias winding – simpler, lower cost tr ansformer • Designed to work with low cost external components Extremely Ene rgy Efficient • Consumes only 30/60 m W at 115/230 VAC with no load • Meets Blue Angel, Energy Star, Energy 2000 a nd 200mW European cell phone requiremen ts for standby • Saves $1 to $4 per y ear in energy costs (at $0.12/kWHr) compared to bulky linear ad.|
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