MLX90132 Datasheet, PDF (8/44 Pages) Melexis Microelectronic Systems – 13.56MHz RFID / NFC Transceiver

MLX90132
13.56MHz RFID / NFC Transceiver
4 Start-up sequence
Once powered-up, the MLX90132 waits for a low pulse on the pin IRQ_IN (greater than 10μs) before
automatically selecting the external interface (SPI or UART) and entering Ready state after a delay of
approximately 2ms.
t₄
VDD
SSI_0
SSI_1
IRQ_IN
t₁
t₀
t₂
t₃
First valid
command
Figure 4: MLX90132 operating states transition
Figure 4 above shows the power-up sequence for a MLX90132 device where:
 t0 is the initial wake-up delay¹⁾
 t1 is the minimum pulse width in IRQ_IN pin¹⁾
 t2 is the delay for the serial interface selection¹⁾
 t3 is the delay before the MLX90132 could accept commands¹⁾
 t₄ is the _VDD ramp-up time¹⁾
100μs (minimum)
10μs (minimum)
250ns (typical)
2ms (minimum)
10ms (maximum)
1) Value specified by design
The following configuration at power on reset (POR) is required to select the communication interface to be
used.
Interface/Pin
SSI_1
SSI_0
SPI
0
1
UART
0
0
Table 3: Selection of the serial communication interface
Notes:
 The Serial Interface is selected after the following falling edge of the pin IRQ_IN when leaving from POR
or Hibernate states.
 When the MLX90132 leaves the IDLE state following a UART_RX/IRQ_IN low level pulse, this pulse is
NOT interpreted as the UART start bit character.
3901090132
Rev. 009
Page 8 of 44
Jan-2014