PCA2002USLASHAA datasheet(8/20 Pages) PHILIPS

8 / 20 page

2004 Jan 20

Philips Semiconductors

Product speciﬁcation

32 kHz watch circuit with programmable

output period and pulse width

PCA2002

handbook, full pagewidth

MGW356

VDD

VP(mod)

VDD(mod)

VSS

VP(start)

tp(start)

t1 t1 t1

tstore

Vstore

Vpre-store

tpre-store

Fig.8 Supply voltage modulation for programming.

CHECKING THE MEMORY CONTENT

The stored data of the OTP array can be checked bit-wise by measuring the supply current. The array word is selected

by the instruction state, the bit is addressed by the shift register. To read a word, the word is first selected (td =t1) and a

logic 1 is written into the first cell of the shift register (td =t3).

This logic 1 is then shifted through the entire shift register (td =t2, so that it points with each clock pulse to the next bit.

If the addressed OTP cell contains a logic 1, a 30 k

Ω resistor is connected between VDD and VSS; this increases the

supply current accordingly.

VDD

VDD(mod)

VP(mod)

(1)

VSS

mgw357

IDD

t1 t1

VP(start)

tp(start)

VP(stop)

tp(stop)

Fig.9 Supply voltage modulation for reading word B.

The corresponding supply current variation for B = 110101 (the sequence is MSB first and LSB last).

(1)

∆I

30 k

Ω

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