Data Sheet AS8118

Revision 1.8, 15-Feb-05

Page 20 of 30

Continuing with the above example, the defined word to be burned will be as follows:

69

68

67

66

65

64

63

62

61

60

59

58

57

56

55

54

53

52

51

0

0

0

0000

0000

0000

0000

50

…

34333231

30292827

26252423

22212019

0

…

0001

0010

1010

0011

18

17

16

15

14

13

12

11

10

98

7654

3210

0

1

0

1001

1011

0101

0001

The following timing diagram shows how the burn procedure is carried out:

TM

DIRO

PROG

69

68

67

4

0

1

2

Startup

define

burn

mode

xL

L

x

L

f1

t2

t3

start

burn

(DIRO=1)

High

Low

High

Low

Vburn

0V

LH

t1

3

H

Note: High and Low refers to VDD and VSS respectively.

The first falling and rising edges on TM define the burn mode and starts it (as can be seen DIRO must be set to logic ‘high’ at

the falling edge, but must be low at the rising edge). Then the first PROM cell is selected. After each rising clock edge on

DIRO the next PROM cell is selected going from MSB to LSB. While one of the PROM cells is selected a defined (low-active)

pulse on TM must be applied to “burn” the respective PROM cell, i.e. write a permanent logic-1 to it.

Important specifications are:

Tburn: Temperature during burn cycle: 25°C

± 10°C

Vburn: 7.50

± 0.25V (at the AS8118 PROG pin)

f1: Maximum DIRO clock frequency is 100kHz

t1: The burn pulse must have a delay of at least 1µs after the previous positive DIRO clock edge

t2: After one burn pulse there must be a delay of at least 1µs before the next PROM cell is selected

t3: The burn pulse width is defined to be 1.0

± 0.2µs. The rise and fall time of the burn pulses on TM must be less than 50ns.

After a burn cycle has been completed, a read cycle must be initiated so that the actual data is loaded. (After “burn” the data

in the internal register is inverted!)

Read

The conditions for ‘burn’ are specified very tightly. In order to be certain that the ‘burn’ process was successful this process

has to be verified. There are 2 modes of readout, a digital readout and analog readout.