IC OFFLINE SWIT OCP 8DIP

LNK306PN

Manufacturer Part NumberLNK306PN
DescriptionIC OFFLINE SWIT OCP 8DIP
ManufacturerPower Integrations
SeriesLinkSwitch®-TN
TypeOff Line Switcher
LNK306PN datasheet
 


Specifications of LNK306PN

Output IsolationNon-IsolatedFrequency Range62 ~ 70kHz
Voltage - Output700VPower (watts)12mW
Operating Temperature-40°C ~ 150°CPackage / Case8-DIP (0.300", 7.62mm), 7 Leads
Output Voltage12 VInput / Supply Voltage (max)265 VAC
Input / Supply Voltage (min)85 VACDuty Cycle (max)72 %
Switching Frequency66 KHzSupply Current250 uA
Operating Temperature Range- 40 C to + 150 CMounting StyleThrough Hole
Lead Free Status / RoHS StatusLead free / RoHS CompliantOther names596-1027-5
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TOPOLOGY
BASIC CIRCUIT SCHEMATIC
Low-Side
Buck Boost –
+
Optocoupler
Feedback
LinkSwitch-TN
V
IN
BP
S
Table 2 (cont). Common Circuit Confi gurations Using LinkSwitch-TN.
provides the lowest cost and highest effi ciency converter. CCM
designs require a larger inductor and ultra-fast (t
freewheeling diode in all cases. It is lower cost to use a larger
LinkSwitch-TN in MDCM than a smaller LinkSwitch-TN in CCM
because of the additional external component costs of a CCM
design. However, if the highest output current is required, CCM
should be employed following the guidelines below.
Topology Options
LinkSwitch-TN can be used in all common topologies, with or
without an optocoupler and reference to improve output voltage
tolerance and regulation. Table 2 provide a summary of these
confi gurations. For more information see the Application
Note – LinkSwitch-TN Design Guide.
Component Selection
Referring to Figure 5, the following considerations may be
helpful in selecting components for a LinkSwitch-TN design.
Freewheeling Diode D1
Diode D1 should be an ultra-fast type. For MDCM, reverse
≤75 ns should be used at a temperature of
recovery time t
rr
70 °C or below. Slower diodes are not acceptable, as continuous
mode operation will always occur during startup, causing high
leading edge current spikes, terminating the switching cycle
prematurely, and preventing the output from reaching regulation.
If the ambient temperature is above 70 °C then a diode with
≤35 ns should be used.
t
rr
For CCM an ultra-fast diode with reverse recovery time
≤35 ns should be used. A slower diode may cause excessive
t
rr
leading edge current spikes, terminating the switching cycle
prematurely and preventing full power delivery.
Fast and slow diodes should never be used as the large reverse
recovery currents can cause excessive power dissipation in the
diode and/or exceed the maximum drain current specifi cation
of LinkSwitch-TN.
V
O
FB
+
D
PI-3756-111903
Feedback Diode D2
≤35 ns)
Diode D2 can be a low-cost slow diode such as the 1N400X
rr
series, however it should be specifi ed as a glass passivated type
to guarantee a specifi ed reverse recovery time. To a fi rst order,
the forward drops of D1 and D2 should match.
Inductor L1
Choose any standard off-the-shelf inductor that meets the
design requirements. A “drum” or “dog bone” “I” core
inductor is recommended with a single ferrite element due to
its low cost and very low audible noise properties. The typical
inductance value and RMS current rating can be obtained from
the LinkSwitch-TN design spreadsheet available within the
PI Expert design suite from Power Integrations. Choose L1
greater than or equal to the typical calculated inductance with
RMS current rating greater than or equal to calculated RMS
inductor current.
Capacitor C2
The primary function of capacitor C2 is to smooth the inductor
current. The actual output ripple voltage is a function of this
capacitor’s ESR. To a fi rst order, the ESR of this capacitor
should not exceed the rated ripple voltage divided by the typical
current limit of the chosen LinkSwitch-TN.
Feedback Resistors R1 and R3
The values of the resistors in the resistor divider formed by
R1 and R3 are selected to maintain 1.65 V at the FB pin. It is
recommended that R3 be chosen as a standard 1% resistor of
2 kΩ. This ensures good noise immunity by biasing the feedback
network with a current of approximately 0.8 mA.
Feedback Capacitor C3
Capacitor C3 can be a low cost general purpose capacitor. It
provides a “sample and hold” function, charging to the output
voltage during the off time of LinkSwitch-TN. Its value should
be 10 μF to 22 μF; smaller values cause poorer regulation at
light load conditions.
LNK302/304-306
KEY FEATURES
1. Output referenced to input
2. Positive output (V
) with respect to +V
O
3. Step up/down – V
> V
or V
< V
O
IN
O
4. Optocoupler feedback
- Accuracy only limited by reference
choice
- Low cost non-safety rated opto
- No pre-load required
5. Fail-safe – output is not subjected to input
voltage if the internal MOSFET fails
IN
IN
2-7
7
Rev. I 11/08