S8024RN Просмотр технического описания (PDF) - Maxim Integrated

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S8024RN

Low-Cost Smart Card Interface

Maxim Integrated 

73S8024RN Data Sheet

DS_8024RN_020

8 Deactivation Sequence

Deactivation is initiated either by the system controller by setting the CMDVCC high, or automatically in

the event of hardware faults. Hardware faults are over-current, overheating, VDD fault, VPC fault, VCC fault,

and card extraction during the session. To be noted that VPC and VCC faults are linked together so that a

fault is generated when VPC goes lower than VCC.

The following steps show the deactivation sequence and the timing of the card control signals when the

system controller sets the CMDVCC high or OFF goes low due to a fault or card removal:

• RST goes low at the end of t1.

• CLK is set low at the end of t2.

• I/O goes low at the end of t3. Out of reception mode.

• VCC is shut down at the end of time t4. After a delay t5 (discharge of the VCC capacitor), VCC is low.

CMDVCC

OFF

RST

CLK

I/O

VCC

-- OR --

t1

t2

t3

t4

t5

t1 = > 0.5µs, timing by 1.5MHz internal Oscillator

t2 = > 7.5µs

t3 = > 0.5µs

t4 = > 0.5µs

t5 = depends on VCC filter capacitor.

For NDS application, CF=1µF makes t1 + t2 + t3 + t4 + t5 < 100µs

Figure 4: Deactivation Sequence

12

Rev. 2

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