78253 SERIES

Application Notes

C&D Technologies (NCL) Ltd

Tanners Drive, Blakelands North

Milton Keynes MK14 5BU, England

Tel: +44 (0)1908 615232

Fax:+44 (0)1908 617545

email: info@cdtechno-ncl.com

www: http://www.dc-dc.com

C&D Technologies (NCL), Inc.

8917 Glenwood Avenue, Raleigh

NC 27612, USA

Tel: +1 (919) 571-9405

Fax: +1 (919) 571-9262

email: info@us.cdtechno-ncl.com

C&D Technologies (NCL) Limited reserve the right to alter or improve the

specification, internal design or manufacturing process at any time, without

notice. Please check with your supplier or visit our web site to ensure that

you have the current and complete specification for your product before use.

© C&D Technologies (NCL) Limited 2000

AN005.1

No part of this publication may be copied, transmitted or stored in a

retrieval system or reproduced in any way including, but not limited to,

photography, photocopy, magnetic or other recording means, without prior

written permission from C&D Technologies (NCL) Limited.

Instructions for use are available from www.dc-dc.com

10mV at full load, further reductions can be

achieved by using larger capacitor values.

The largest recommended capacitor for the

first stage smoothing is 22µF, up to 47µF can

be used if required after the series inductor.

The output filter capacitors should exhibit low

effective equivalent series resistance (ESR) at

the switching frequency. Tantalum or ceramic

capacitors are the recommended choice of

dielectric.

TRANSFORMER ISOLATED ADC

The circuit in figure 4 offers a very low

quiescent current for an isolated interface by

using logic compatible tranfomer

isolator/translator devices (1635). The

isolators require some additional logic to

interface with the ADC and a 3.3V logic

controller, a few 74HC IC's and two delay

lines are all that is required to implement full

control over the ADC and its output.

Figure 4: Transformer Isolated ADC

Figure 5: Typical Characteristics (Voltage Curves)

0

20

40

60

80 100 120

Output Current (mA)

FS=High

FS=Low

78253/35(M)

10

8

6

4

2

0

0

100

200

300

400

Output Current (mA)

FS=Low/High

78253/55(M)

10

8

6

4

2

0

0

20

40

60

80

100

Output Current (mA)

FS=High

FS=Low

78253/35(M)V

10

8

6

4

2

0

0

100

200

300

400

Output Current (mA)

FS=High

FS=Low

78253/55(M)V

10

8

6

4

2

0

0

20

40

60

80 100 120

Output Current (mA)

FS=High

FS=Low

78253/35(M)

100

80

60

40

20

0

0

100

200

300

400

Output Current (mA)

FS=Low/High

78253/55(M)

100

80

60

40

20

0

0

20

40

60

80

100

Output Current (mA)

FS=High

FS=Low

78253/35(M)V

100

80

60

40

20

0

0

100

200

300

400

Output Current (mA)

FS=Low

FS=High

78253/55(M)V

100

80

60

40

20

0

-50 -25

0

25

50

75 100

Temperature (°C)

FS=Low

78253/35(M)

110

105

100

95

90

FS=High

-50

-25

0

25

50

75 100

Temperature (°C)

FS=Low

78253/55(M)

110

105

100

95

90

FS=High

-50

-25

0

25

50

75 100

Temperature (°C)

FS=Low

78253/35(M)V

110

105

100

95

90

FS=High

-50 -25

0

25

50

75 100

Temperature (°C)

FS=Low

78253/55(M)V

110

105

100

95

90

FS=High

EFFICIENCY CURVES

VOLTAGE DEVIATION

VOLTAGE CURVES