Off-line Switcher. TNY256GN Datasheet

TNY256GN Switcher. Datasheet pdf. Equivalent


Power Integrations TNY256GN
®
TNY256
TinySwitch® Plus
Energy Efficient, Low Power Off-line Switcher
Product Highlights
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
integrated/hybrid solutions
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
Description
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.
+
Optional
UV Resistor
Wide-Range
HV DC Input
D
TinySwitch Plus
S
EN/UV
BP
Figure 1. Typical Standby Application.
+
DC Output
PI-2363-022699
OUTPUT POWER CAPABILITY*
ORDER
PART
NUMBER
PACKAGE
230 VAC or
115 VAC
w/Doubler
85-265
VAC
TNY256P
TNY256G
TNY256Y
DIP-8
SMD-8
TO-220-7B
8-15 W
8-19 W
5-10 W
5-11 W
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.
July 2001


TNY256GN Datasheet
Recommendation TNY256GN Datasheet
Part TNY256GN
Description Low Power Off-line Switcher
Feature TNY256GN; ® TNY256 TinySwitch® Plus Energy Efficient, Low Power Off-line Switcher Product Highlights TinySwit.
Manufacture Power Integrations
Datasheet
Download TNY256GN Datasheet




Power Integrations TNY256GN
TNY256
BYPASS
(BP)
50 µA
LINE UNDER-VOLTAGE
AUTO-
RESTART
COUNTER
CLOCK
RESET
REGULATOR
5.8 V
5.8 V
5.1 V
BYPASS PIN
UNDER-VOLTAGE
+
-
DRAIN
(D)
1.5 V + VTH
ENABLE/
UNDER-VOLTAGE
(EN/UV)
1.5 V
JITTER
CLOCK
DCMAX
OSCILLATOR
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.
2
C
7/01
VILIMIT
THERMAL
SHUTDOWN
S
Q
R
Q
LEADING
EDGE
BLANKING
SOURCE
(S)
PI-2367-122398
Tab Internally
Connected to SOURCE Pin
7D
5 NC
4S
3 BP
1 EN/UV
Y Package (TO-220-7B)
BP 1
S2
S3
EN/UV 4
8S
7S
6S
5D
P Package (DIP-8)
G Package (SMD-8)
Figure 3. Pin Configuration.
NO CONNECT (N) Pin
No connection.
PI-2500-031501



Power Integrations TNY256GN
TinySwitch Functional Description
TinySwitch combines a high voltage power MOSFET switch
with a power supply controller in one device. Unlike conventional
PWM (Pulse Width Modulator) controllers, TinySwitch uses a
simple ON/OFF control to regulate the output voltage.
The TNY256 controller consists of an Oscillator, Enable (Sense
and Logic) circuit, 5.8 V Regulator, Bypass pin Under-Voltage
circuit, Over Temperature Protection, Current Limit circuit,
Leading Edge Blanking and a 700 V power MOSFET. The
TNY256 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
130 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 TNY256 oscillator incorporates circuitry that introduces a
small amount of frequency jitter, typically 5 kHz peak-to-peak,
to minimize EMI emission. The modulation rate of the frequency
jitter (1 kHz) is set 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 Figure4 illustrates the
frequency jitter of the TNY256.
Enable Input Circuit
The enable input circuit at the EN/UV pin consists of a low
impedance source follower output set at 1.5 V. The current
through the source follower is limited to 50 µA with 10 µA of
hysteresis. When the current drawn out of the this pin exceeds
600
500
VDRAIN
400
300
200
100
0
132.5 kHz
127.5 kHz
0
.5
1
Time (µs)
Figure 4. Frequency Jitter.
TNY256
50 µA, a low logic level (disable) is generated at the output of
the enable circuit. This 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), otherwise
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.
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 1.5 V, in the
disabled state. This improves the response time of the
optocoupler that is usually connected to this pin.
5.8 V Regulator
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, whenever the MOSFET is off. The BYPASS
pin is the internal supply voltage node for the TinySwitch.
When the MOSFET is on, the TinySwitch runs off of the energy
stored in the bypass capacitor. Extremely low power
consumption of the internal circuitry allows the TinySwitch to
operate continuously from the current drawn from the DRAIN
pin. A bypass capacitor value of 0.1 µF is sufficient for both
high frequency de-coupling and energy storage.
BYPASS Pin Under-Voltage
The BYPASS pin under-voltage circuitry disables the power
MOSFET when the BYPASS pin voltage drops below 5.1 V.
Once the BYPASS pin voltage drops below 5.1 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 set at 135 oC with 70 oC hysteresis. When the
die temperature rises above this threshold (135 oC) the power
MOSFET is disabled and remains disabled until the die
temperature falls by 70 oC, at which point it is re-enabled.
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 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 primary-side 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
3 C
7/01





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