P4022 datasheet(4/13 Pages) EMMICRO

4 / 13 page

PRELIMINARY

EMMICROELECTRONIC-MARINSA

P4022

Current Consumption

The total typical current consumption from the

storage capacitor CP in various modes is shown in

Table 4 below.

The total current consumption in conjunction with

the size of the power storage capacitance

determines the maximum time that transistor Q2

can be turned on and Q1 turned off, before the

supply voltage drops below 1 V, thereby resulting

in the power-on reset block resetting the chip.

This in turn determines the minimum data bit rate

and maximum range. Similarly the total storage

capacitance and total current determine the

maximum unpowered SWITCHED-OFF state time.

The second column shows the current drawn in

FREE-RUNNING mode. The third column shows

the current drawn for the bi-directional protocols,

which includes the current drawn by the GAP

input pull-up. The fourth column shows the total

current drawn in SWITCHED-OFF state.

In this

mode both the GAP input and the shunt regulator

draws current from the storage capacitor.

Supply

(V)

Current

(Free)

(

µA)

Current

(Bi-directional)

(

µA)

Current

(SWTICHED-

OFF state)

(

µA)

1.0

1.8

2.2

2.8

1.2

2.6

3.6

4.6

1.5

3.8

6.3

8.3

2.0

3.0

Table 4

Table 5 below shows the theoretical storage

capacitance required for various applications.

For free-running applications, the capacitance

required is determined by the data bit rate and

encoding method.

Only the Logic, PON and

oscillator

draw

current

Free-running

applications. For the bi-directional protocols, the

GAP input pull-up also draws current during

modulation.

Data bit

rate

(kbit/s)

En-

coding

Free-

running

(pF)

Bi-direc-

tional

(pF)

Counting

(

µF)

Man

2700

3600

Glitch

670

900

Man

170

240

Glitch

Table 5

For counting applications (SWITCH-OFF BTG-

Supertag) the required unpowered time in the

SWITCHED-OFF state determines the size of the

capacitor. In applications where the chip can be

guaranteed to stay powered, the capacitor size is

determined by the data bit rate

It should be noted that the on-chip capacitance is

sufficient for free-running applications at 64 kbit/s,

while inductive applications at 4 kbit/s require a

few nanofarad externally.

Unpowered counting

applications will require more than 20

µF to

achieve 1 second unpowered time

the

SWITCHED-OFF state.

P4022 Datasheet(PDF) 4 Page - EM Microelectronic - MARIN SA

P4022 Datasheet(HTML) 4 Page - EM Microelectronic - MARIN SA

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13

Datasheet Download

Link URL