MC33690 データシートの表示（PDF） - Freescale Semiconductor

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MC33690

Standalone Tag Reader Circuit

Freescale Semiconductor 

Standalone Configuration with One-Wire Bus

Table 4. Communication Modes Description

Configuration

Type

Bus Type

Configuration Pins

Name Mode1 Mode2

Pin Status Function Description

Standalone 1 wire (VBAT) A

0

0 K output/input:

• demodulator output

• amplitude modulation input

• shutdown/wake-up

AM must be connected to VSUP

DOUT forces a low level

2 wires (VBAT) B

0

1 K output:

• demodulator output

AM input:

• amplitude modulation input

• shutdown/wake-up

DOUT forces a low level

Direct

2 wires (VDD)

C

1

x DOUT output:

Connection to

• demodulator output

a MCU

AM input:

• amplitude modulation input

MODE2 input:

• shutdown/wake-up

1 K output/input (standalone ISO 9141 interface):

• driven by Tx and monitored by Rx

0 K input (standalone ISO 9141 interface):

• monitored by Rx

• Tx disabled

7 Standalone Configuration with One-Wire Bus

When a low level is applied on pins MODE1 and MODE2, the circuit is in configuration A (see Figure 24). After power on, the

circuit is set into read mode. The demodulator output is directly routed to the ISO 9141 interface output K.

The circuit can be set into write mode at anytime by violation of all possible patterns on the single wire bus during more than

1ms. Then, the K line achieves the amplitude modulation by switching on/off both antenna drivers.

After 1ms of inactivity at the end of the challenge phase (bus in idle recessive one state), the circuit is set back into read mode.

The circuit can be put into standby mode by forcing the K line at zero during more than 2 ms after entering the write mode.

After the K line is released, the circuit sends an acknowledge pulse before entering into standby mode. In standby mode, the

oscillator and most of the internal biasing currents are switched off. Therefore, the functions (tag reader, ISO 9141 driver) are

inactive except the voltage regulator and the ISO 9141 receiver on pin K. The driver output TD1 forces a low level and TD2

forces a high level. A rising edge on K wakes up the circuit. After completion of the wake-up sequence, the circuit is

automatically set in read mode.

In configuration A, DOUT and Rx outputs always force a low level and Tx is disabled.

MC33690 Standalone Tag Reader Circuit, Rev. 5

10

Freescale Semiconductor

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