SMT PLANAR TRANSFORMER
AND PLANAR INDUCTOR
For use with Linear Technologys
PLANAR TRANSFORMER PA0191
LT1681 and LTC1698
Power Rating: 60-100W
Height: 8.3 mm Max
Footprint: 27.7 mm x 21.8 mm Max
PLANAR INDUCTOR P1977
Energy Storage: 420 J (2.1 H/20A)
Height: 8.3 mm Max
Footprint: 21.7 mm x 20.3 mm Max
Electrical Specifications @ 25C Operating Temperature -40C to 125C
Primary Primary Leakage DCR
Part Power Turns Ratio
Secondary Inductance Inductance
Primary Primary Aux. Secondary
1
Number Rating (with 7T Pri. Aux.)
Isolation (H MIN) (H MAX)
(m MAX) (m MAX) (m MAX)
PA0191 60-100 W 9:2 1500 Vdc Basic 100 1.5 85 800 2.5
Electrical Specifications @ 25C Operating Temperature -40C to 125C
3
2 DCR Saturation Current
Inductance Inductance Heating
Part Irated
4
(m ) (A)
@Irated @ 0 A Current
DC
Number (A )
DC
(A)
(H 5%) (H 5%)
TYP MAX @ 25C @ 125C
P1977 2.1 20 1.00 1.25 2.1 27.0 22.5 31
Mechanicals Schematics
PA0191
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PA0191 P1977
Weight ..................11.0 grams ..................10.8 grams
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Tape & Reel...............150/reel.......................150/reel
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Tray.............................55/tray.........................48/tray
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Inches
Dimensions:
mm
.010
%
Unless otherwise specified, all tolerances are
0,25
US 619 674 8100 UK 44 1483 401 700 France 33 3 84 35 04 04 Singapore 65 287 8998 Taiwan 886 2 2698 0228 Hong Kong 852 2788 6588 SMT PLANAR TRANSFORMER
AND INDUCTOR
For use with Linear Technologys LT1681 and LTC1698
Notes from Tables
For PA0191: Basic Insulated Planar Transformer
1.To determine if the transformer is suitable for your application it
the specified ambient environment and applying a short duration
is necessary to ensure that the temperature rise of the compo-
pulse current (to eliminate self-heating effects) to the compo-
nent (ambient plus temp. rise) does not exceed its operating
nent.
temperature. To determine the temperature rise of the compo-
4.The heating current is the dc current which causes the tempera-
nent it is necessary to calculate the total power losses (copper
ture of the part to increase by approximately 40C. This current
and core) in the application.
is determined by mounting the component on a PCB with a .25"
Total Copper Losses
wide (2 ounce equivalent copper traces) and applying the
CopperTotal (W) = sum of the losses in each winding current to the device for 30 minutes.
The losses in each winding can be calculated by: 5.In high volt*time applications additional heating in the compo-
2
nent can occur due to core losses in the inductor which may
CopperWindingX (W) = .001 * DCR(m ) * (Irms )
neccessitate derating the current in order to limit the tempera-
Core Losses
ture rise of the component. In order to determine the approxi-
To calculate the core loss, use the following formula:
mate total losses (or temperature rise) for a given application
1.7 2.5
CoreLoss (W) = 2.5E-8 * (Freq kHz) * ( B/2000)
both copper and core losses should be taken into account.
where:
Total Copper Losses
B/2000 = 1.01 * (Voltage Min * Dutycycle Max/Freq kHz)
2
CopperTotal (W) = .001* DCR(m ) * (Irms )
Temperature Rise
where:
TempRise (C) = .603 * CopperTotal (W) * (50.6 * CoreLoss
2 2 .5
Irms = (IDC + ( I/2) )
(W)/CopperTotal (W) + 88.1)
Core Losses
For P1977: Planar Inductor
To calculate the core loss, use the following formula:
2.The rated current as listed is either the saturation current or the
1.7 2.5
CoreLoss (W) = 2.5E-8 * (Freq kHz) * (.0635 * I)
heating current depending on which value is lower.
Temperature Rise
3.The saturation current is the current which causes the induc-
tance to drop by 10% at the stated ambient temperatures (25C, TempRise (C) = .603 * CopperTotal (W) * (50.6 * CoreLoss
125C). This current is determined by placing the component in (W)/CopperTotal (W) + 88.1)
APPLICATION NOTES
The PA0191 transformer and P1977 inductor were designed for
use with Linear Technology's LT1681 and LTC1698 IC's and are
featured in Linear Technology's Design note 261 which details the
solution for a low cost, discrete component alternative to telecom
power modules.
The PA0191 transformer and P1977 inductor were designed for
(but not limited to) the following application:
Topology Two-switch forward
Frequency 230 kHz
Pri./Sec. Isolation Basic Insulation (1500 Vdc)
Input Voltage 36-72 v telecom input
Output Voltage(s) 3.3 v / 20 A output (with an auxilary
primary side control winding - 12 v/100 mA)
+ +
For More Information :
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