76250 SERIES
Converter Transformers
features
p
p
p
p
p
p
p
p
p
Maxim Compatible
BS EN 60950 Approved
Isolation to 6kV
Toroidal Construction
Standard Pinout
UL 94V-0 Package Material
Fully Encapsulated
Low Profile
Industrial Temp. Range Available
pin connections
6 Pin DIP (top view)
description
The 76250 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 `EN' devices
are fully approved to BS EN 60950 for use in
telecoms applications.
Primary
1
3
5
Secondary
2
4
6
Pulse Transformers
4-41
4 - 76250 SERIES
76250 SERIES
Converter Transformers
absolute maximum ratings over operating free air temperature range
Operating free air temperature range . . . . . . . . . . . . . . . . . . . 0°C to 70°C
Operating free air temperature range 76250X . . . . . . . . . . . . . . –40°C to 85°C
Storage temperature range . . . . . . . . . . . . . . . . . . . . . . –60°C to 125°C
Lead Temperature 1.5mm from case for 10 seconds . . . . . . . . . . . . . . . 300°C
Peak current I
PK
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300mA
Isolation voltage 76250 76250X (flash tested for 1 second) . . . . . . . . . 1500Vrms
Isolation voltage 76250EN (flash tested for 1 second) . . . . . . . . . . . . 6000VDC
Isolation voltage 76250KV4 (flash tested for 1 second) . . . . . . . . . . . . 4000Vrms
electrical specifications over operating free air temperature range
76250
Parameter
Turns Ratio
Primary Inductance, L
P
Leakage Inductance, L
L
Interwinding Capacitance, Cww
DC Resistance, R
DC
Volt-time Product, E
T
Note : All data taken at T
A
= 25°C.
Test
Conditions
N
P
:N
S
100kHz, 100mV
100kHz, 100mV
100kHz, 100mV
< 0.1VDC
5kHz, 5V
Value
Min.
Typ.
1CT:1
1.0
2.0
2.0
50
1.0
50
2.5
3.0
100
2.0
Max.
Package
Style
Unit
mH
1
mH
pF
W
Vms
4-42
76250 SERIES
Converter Transformers
electrical specifications over operating free air temperature range
76250KV4
Parameter
Turns Ratio
Primary Inductance, L
P
Leakage Inductance, L
L
Interwinding Capacitance, C
WW
DC Resistance, R
DC
Volt-time Product, E
T
Test
Conditions
N
P
:N
S
100kHz, 100mV
100kHz, 100mV
100kHz, 100mV
< 0.1VDC
5kHz, 5V
50
1.0
Value
Min.
Typ.
1CT:1
2.0
35
5.0
1.0
2.5
40
10
2.0
1
mH
mH
pF
W
Max.
Package
Style
Unit
Vms
76250EN
Parameter
Turns Ratio
Primary Inductance, L
P
Leakage Inductance, L
L
Interwinding Capacitance, C
WW
DC Resistance, R
DC
Volt-time Product, E
T
Note : All data taken at T
A
= 25°C.
Test
Conditions
N
P
:N
S
10kHz, 100mV
100kHz, 100mV
100kHz, 100mV
< 0.1VDC
5kHz, 5V
Value
Min.
Typ.
1CT:1
1.0
2.0
35
5.0
1.0
50
2.5
40
10
2.0
Max.
Package
Style
Unit
mH
2
mH
pF
W
Vms
Pulse Transformers
4-43
4 - 76250 SERIES
76250 SERIES
Converter Transformers
electrical specifications over operating free air temperature range
76250X
Parameter
Turns Ratio
Primary Inductance, L
P
Leakage Inductance, L
L
Interwinding Capacitance, C
WW
DC Resistance, R
DC
Volt-time Product, E
T
Note : All data taken at T
A
= 25°C.
Test
Conditions
N
P
:N
S
10kHz, 100mV
100kHz, 100mV
100kHz, 100mV
< 0.1VDC
10kHz, 5V
Value
Min.
Typ.
1CT:1
2.5
3.25
0.45
50
1.0
35
40
4.0
3.0
100
2.0
Max.
Package
Style
Unit
mH
1
mH
pF
W
Vms
The 76250EN converter transformer was tested by British Standards Institute (BSI) and
received certificate numbers 7819 and 7820 confirming compliance with :
BS EN 60950 : 1994
BS EN 41003 : 1992
(BS 415 : 1994)
(BS 7002 : 1992)
EN 60950 is derived from IEC 950 and is equivalent to UL 1950 and CSA 950 standards.
4-44
76250 SERIES
Converter Transformers
typical application
isolated RS-232 interface
+5V
8
EN
1
SHUTDOWN
4
T1IN
IN4148
D1 2
V
CC
14
D2 13
1
3
5
76250
2
6
1 AC
–V 13
1mF
+
+V 2
+
1mF
–10 VOUT
T1
RTS
T1L
3
1
2
5
6
4
3 T1DIN
T1
+10 VOUT
T1O
12
CTS
TD
5
T2IN
T2
T2L
6
+
4
T2DIN
T2
SG
T2O
11
TD
5
9
4
3
2
6
1
8
7
RTS
DSR
CTS
9
R1OUT
R1
R1DIN
10
1mF
5
R1L
R1
R1IN
10
RD
DCD
RD
12
R2OUT
GND
R2
R2DIN
11
6
R2L
7
OPTO's*
BYP
R2
R2IN
9
14
9 Pin D-Type Connector
ISO GND
4.7mF
MAX250
OPTO'S* - 4 x 4N26 (76250),
Isolation Barrier
MAX251
4 x CNY17-3 or 4 x SFH610 (76250KV4 & 76250EN).
Pulse Transformers
4-45
4 - 76250 SERIES