FEATURES
n Maxim Compatible
n Isolation to 4kV
n Surface Mount Options
n Toroidal Construction
n Standard Pinout
n UL 94V-0 Package Material
n Fully Encapsulated
n Low Profile
n Industrial Temperature Range
DESCRIPTION
The 78250 series of converter transformers
are specifically designed for use with Maxim
chipsets to provide isolated RS232 interfaces.
Carefully controlled turns ratios ensure
consistent performance whilst a toroidal
construction minimises EMI. The surface
mount devices are fully compatible with
CECC00802 to 280°C which allows them to
be placed and reflowed with IC’s thus
reducing time and cost in production.
SELECTION GUIDE 78250/78250M
Parameter Conditions MIN TYP MAX Units
Primary Inductance, LP 10kHz, 100mV 1.0 2.0 2.5 mH
Leakage Inductance, LL 100kHz, 100mV 2.0 3.0 µH
Interwinding Capacitance, CWW 100kHz, 100mV 69 90 pF
D.C. Resistance, RDC <0.1VDC 1.0 2.0 Ω
Volt-time Product, ET 5kHz, 5V 50 Vµs
SELECTION GUIDE 78250V/78250MV
Parameter Conditions MIN TYP MAX Units
Primary Inductance, LP 10kHz, 100mV 1.0 2.0 2.5 mH
Leakage Inductance, LL 100kHz, 100mV 35 40 µH
Interwinding Capacitance, CWW 100kHz, 100mV 9 12 pF
D.C. Resistance, RDC <0.1VDC 1.4 1.8 Ω
Volt-time Product, ET 5kHz, 5V 50 Vµs
Operating free air temperature range –40°C to 85°C
Storage temperature range –50°C to 125°C
Lead Temperature 1.5mm from case for 10 seconds 300°C
Peak current IPK 300mA
Isolation voltage 78250(M) (flash tested for 1 second) 1500Vrms
Isolation voltage 78250V(M) (flash tested for 1 second) 4000Vrms
ABSOLUTE MAXIMUM RATINGS
All specifications typical at TA= 2 5 ° C .
78250 SERIES
Converter Transformers
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