MC33596 Datasheet, PDF (28/70 Pages) Freescale Semiconductor, Inc – PLL Tuned UHF Receiver for Data Transfer Applications

Power-On Reset and MC33596 Startup
STROBE
CONFB
SPI Startup Time
SEB
Figure 21. Valid Sequence from Standby/LVD Mode to Configuration Mode
Figure 22 describes the sequence for enabling a correct transition from receive mode to configuration
mode.
1. MC33596 is in receive mode.
2. CONFB is forced to low level during one digital period T_digclk in order to reset the state machine
only.
3. CONFB is set to high level during the time length of an ID.
1
2
3
S TRO BE
C ONFB
SEB
SCLK
MOSI
Figure 22. Valid Sequence from Receive Mode to Configuration Mode
14 Power-On Reset and MC33596 Startup
The startup sequence can be divided into three stages as defined in Figure 23:
1. The power supply is applied to the MC33596 and an external pullup resistor on CONFB is required
to enter standby mode. SEB can be either set to low level if the SPI access is not shared with
another external MCU, or connected to an external pullup resistor (see Section 9, “MCU
Interface”).
During this stage and during the ramp-up of the power supply, signals from the MCU connected to
the MC33596 are undefined. That is why the MC33596 must start in standby mode.
NOTE
Along with the ramp-up of power supply, one of these two conditions must
be complied with:
— Power supply of the MC33596 must rise in 1 ms from 0 V to 3 V.
— The level on STROBE pin is lower than 0.75 V until the power supply reaches 3 V.
MC33596 Data Sheet, Rev. 4
28
Freescale Semiconductor