EP-91 12 V, 1 A, Universal Input Supply
7-Feb-2006
8 Transformer Spreadsheet
ACDC_TinySwitch-III
_011906; Rev.0.27;
Copyright Power
Integrations 2006
INPUT
INFO
OUTPUT UNIT
ACDC_TinySwitch-III_011906_Rev0-27.xls;
TinySwitch-III Continuous/Discontinuous
Flyback Transformer Design Spreadsheet
ENTER APPLICATION VARIABLES
EP91 - 12 V, 1 A, Universal Input
Minimum AC Input Voltage
Maximum AC Input Voltage
VACMIN
VACMAX
fL
85
265
50
Volts
Volts
Hertz
Volts
Amps
AC Mains Frequency
VO
IO
12.00
1.00
Output Voltage (at continuous power)
Power Supply Output Current (corresponding to
peak power)
Power
n
12 Watts
Continuous Output Power
Efficiency Estimate at output terminals. Unter 0.7 if
no better data available
Z Factor. Ratio of secondary side losses to the total
losses in the power supply. Use 0.5 if no better data
available
0.71
0.50
Z
tC
3.00
mSeconds Bridge Rectifier Conduction Time Estimate
CIN
28.80
28.8 uFarads
Input Capacitance
ENTER TinySwitch-III VARIABLES
TinySwitch-III
TNY278
TNY278
User defined TinySwitch-III
Chosen Device
Chose Configuration
TNY278
STD
Standard
Current Limit
Enter "RED" for reduced current limit (sealed
adapters), "STD" for standard current limt or "INC"
for increased current limit (peak or higher power
applications)
ILIMITMIN
ILIMITTYP
ILIMITMAX
fSmin
0.512 Amps
0.550 Amps
0.588 Amps
124000 Hertz
35.937 A^2kHz
Minimum Current Limit
Maximum Current Limit
Minimum Device Switching Frequency
I^2f (product of current limit squared and frequency
is trimmed for tighter tolerance)
I^2fmin
VOR
101.00
101 Volts
Reflected Output Voltage (VOR < 135 V
Recommended)
VDS
VD
KP
10 Volts
0.7 Volts
0.60
TinySwitch-III on-state Drain to Source Voltage
Output Winding Diode Forward Voltage Drop
Ripple to Peak Current Ratio (KP < 6)
KP_TRANSIENT
0.38
Transient Ripple to Peak Current Ratio. Ensure
KP_TRANSIENT > 0.25
ENTER BIAS WINDING VARIABLES
VB
NB
VZOV
22.00 Volts
12.13
28.00 Volts
Bias Winding Voltage
Bias Winding Number of Turns
Over Voltage Protection zener diode.
UVLO VARIABLES
V_UV_TARGET
92
92.00 Volts
92.20 Volts
Target under-voltage threshold, above which the
power supply with start
Typical start-up voltage based on standard value of
RUV_ACTUAL
V_UV_ACTUAL
RUV_IDEAL
RUV_ACTUAL
3.59 Mohms
3.60 Mohms
Calculated value for UV Lockout resistor
Closest standard value of resistor to RUV_IDEAL
ENTER TRANSFORMER CORE/CONSTRUCTION VARIABLES
Core Type
Core
Bobbin
AE
LE
AL
EE25
EE25
User-Selected transformer core
PC40EE25-Z
EE25_BOBBIN
Core Effective Cross Sectional Area
Core Effective Path Length
Ungapped Core Effective Inductance
EE25
P/N:
EE25_BOBBIN P/N:
0.404 cm^2
7.34 cm
1420 nH/T^2
Power Integrations
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