TNY278GN Power Integrations, TNY278GN Datasheet - Page 9

IC OFFLINE SWIT OVP OTP HV 8SMD

TNY278GN

Manufacturer Part Number
TNY278GN
Description
IC OFFLINE SWIT OVP OTP HV 8SMD
Manufacturer
Power Integrations
Series
TinySwitch®-IIIr
Datasheet

Specifications of TNY278GN

Output Isolation
Isolated
Frequency Range
124 ~ 140kHz
Voltage - Output
700V
Power (watts)
28W
Operating Temperature
-40°C ~ 150°C
Package / Case
8-SMD Gull Wing, 7 Leads
Output Voltage
12 V
Input / Supply Voltage (max)
265 VAC
Input / Supply Voltage (min)
85 VAC
Duty Cycle (max)
65 %
Switching Frequency
132 KHz
Supply Current
445 uA
Operating Temperature Range
- 40 C to + 150 C
Mounting Style
SMD/SMT
No. Of Outputs
1
Voltage Regulator Case Style
SMD
No. Of Pins
8
Base Number
278
Controller Type
PWM
Frequency
132kHz
Rohs Compliant
Yes
For Use With
596-1194 - KIT DESIGN REF TINYSWITCH-III
Lead Free Status / RoHS Status
Lead free / RoHS Compliant

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Undervoltage lockout is confi gured 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 fi lter (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 fl exibility 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.
Further fl exibility 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.
2.
3.
4.
5.
6.
7.
www.powerint.com
Standard current limit (I
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 (I
currents and therefore improved effi ciency, 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 (I
applications requiring higher peak power or continuous power
where the thermal conditions allow.
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.
Effi ciency of 75%.
Minimum data sheet value of I
Transformer primary inductance tolerance of ±10%.
Refl ected output voltage (V
Voltage only output of 12 V with a fast PN rectifi er diode.
Continuous conduction mode operation with transient K
value of 0.25.
LIMITred
LIMITinc
or I
or I
LIMIT
LIMIT
-1) offering reduced RMS device
LIMIT
+1), extending the power capability for
) is selected with a 0.1 μF BP/M pin
OR
) of 135 V.
2
f.
P
*
8.
9.
10.
*Below a value of 1, K
current. To prevent reduced power capability due to premature
termination of switching cycles a transient K
recommended. This prevents the initial current limit (I
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 fi lter, the BP/M pin capacitor forms an external fi lter
providing noise immunity from inadvertent triggering. For the
bypass capacitor to be effective as a high frequency fi lter, the
capacitor should be located as close as possible to the
SOURCE and BP/M pins of the device.
Peak Output Power Table
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.
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 fi ltering can be achieved by inserting a low
Table 2.
TNY274P/G
TNY275P/G
TNY276P/G
TNY277P/G
TNY278P/G
TNY279P/G
TNY280P/G
Increased current limit is selected for peak and open frame
power columns and standard current limit for adapter
columns.
The part is board mounted with SOURCE pins soldered to a
suffi cient area of copper and/or a heatsink is used to keep
the SOURCE pin temperature at or below 110 °C.
Ambient temperature of 50 °C for open frame designs and
40 °C for sealed adapters.
Product
Minimum Practical Power at Three Selectable Current Limit Levels.
10.8 W
11.8 W 15.3 W 19.4 W
15.1 W 19.6 W 23.7 W 11.8 W 15.3 W 18.5 W
19.4 W
23.7 W 28.4 W 32.2 W 18.5 W
I
28 W
LIMIT
8 W
230 VAC ± 15%
-1
P
is the ratio of ripple to peak primary
10.9 W
32.7 W 36.6 W 21.8 W 25.4 W 28.5 W
12 W
24 W
I
LIMIT
15.1 W
I
9.1 W
28 W
LIMIT
TNY274-280
+1 I
15.1 W 18.6 W 21.8 W
7.1 W
8.4 W
9.2 W
LIMIT
P
-1
limit of ≥0.25 is
85-265 VAC
11.9 W 15.1 W
8.5 W
9.3 W
22 W
I
LIMIT
INIT
) from
Rev. I 01/09
11.8 W
25.2 W
I
7.1 W
LIMIT
9
+1

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