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TJA1083 Datasheet PDF : 41 Pages
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NXP Semiconductors
TJA1083
FlexRay node transceiver
Table 6. State transitions
indicates the action that initiates a transaction; 1 and 2 are the consequences of a transaction.
Transition
UVVIO
flag[1]
UVVCC
flag[1]
wake flag[1] PWON flag[1] STBN
VCC level
Normal to Standby
Standby to Normal
Standby to Power-off
Power-off to Standby
cleared
set
cleared
cleared
cleared
cleared
X
X
cleared
cleared
set
cleared
cleared
cleared
set
set
cleared
cleared
cleared
1 cleared
1 cleared
1 cleared
X
X
cleared
cleared
cleared
2 cleared
2 cleared
2 cleared
X
1 set
L
H
H
H
H
H
X
X
VCC > Vuvd(VCC)
VCC > Vuvd(VCC)
Vuvd(VCC) > VCC > Vth(det)POR
VCC > Vuvd(VCC)
VCC > Vuvd(VCC)
Vuvd(VCC) > VCC > Vth(det)POR
VCC < Vth(det)POR
VCC > Vth(rec)POR
[1] See Table 7 for set and reset conditions of all flags.
6.2 Power-up and power-down behavior
6.2.1 Power-up
The TJA1083 has two supply pins: VCC (+5 V) and VIO (for the voltage level adaptation).
The ramp up of the different power supplies can vary, depending on the state or value of a
number of signals and parameters. The power-up behavior of the TJA1083 is not affected
by the sequence in which power is supplied to these pins or by the voltage ramp up.
As an example, Figure 6 shows one possible power supply ramp-up scenario. The digital
section of the TJA1083 is supplied by VCC. The voltage on pin VCC ramps up before the
voltage on pin VIO. As long as the voltage on VCC remains below the power-on reset
recovery threshold, Vth(rec)POR, the internal state machine is inactive and the transceiver is
totally passive, remaining in Power-off mode. As soon as the voltage rises above the
Vth(rec)POR threshold, the internal state machine starts running, setting the PWON flag and
switching the TJA1083 to Standby mode. This initializes the VCC and VIO under-voltage
flags to the set state (since both VCC and VIO are actually in undervoltage state just after
power-on).
Once both VIO and VCC have reached their operating ranges, the under-voltage flags are
reset. The operating mode is then determined by the level on STBN (the TJA1083
switches to Normal mode if STBN is HIGH and remains in Standby mode if STBN is
LOW), provided VIO and VCC are above their respective undervoltage recovery levels
(Vuvr(VIO) and Vuvr(VCC)).
TJA1083
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 1 — 10 October 2012
© NXP B.V. 2012. All rights reserved.
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