uja1066 NXP Semiconductors, uja1066 Datasheet - Page 17

• Manufacturer Part Number: uja1066
• Description: High-speed Can Fail-safe System Basis Chip
• Manufacturer: NXP Semiconductors

NXP Semiconductors
UJA1066_2
Product data sheet
6.6.1.1 SYSINH output
6.6.3.1 Voltage regulator V1
6.5.2 EN output
6.6.1 BAT14, BAT42 and SYSINH
6.6.2 SENSE input
6.6.3 Voltage regulators V1 and V2
6.6 Power supplies
Pin RSTN is monitored for a continuously clamped LOW condition. If the SBC pulls RSTN
HIGH, but it remains LOW for longer than t
mode since this indicates an application failure.
The SBC also detects if pin RSTN is clamped HIGH. If the SBC pulls RSTN LOW, but it
remains HIGH for longer than t
mode since the microcontroller can no longer be reset. On entering Fail-safe mode, the V1
voltage regulator shuts down and the microcontroller stops running.
Additionally, chattering reset signals are handled by the SBC in such a way that the
system safely falls back to Fail-safe mode with the lowest possible power consumption.
Pin EN can be used to control external hardware, such as power components, or as a
general purpose output if the system is running properly. During all reset events, when pin
RSTN is pulled LOW, the EN control bit is cleared and pin EN is forced LOW. It will remain
LOW after pin RSTN is released. In Normal and Flash modes, the microcontroller can set
the EN control bit via the SPI. This releases pin EN, which goes HIGH.
The SBC contains two supply pins, BAT42 and BAT14. BAT42 supplies most of the SBC
while BAT14 only supplies the linear voltage regulators and the INH/LIMP output pin. This
supply architecture facilitates different supply strategies, including the use of external
DC-to-DC converters controlled by pin SYSINH.
The SYSINH output is a high-side switch from BAT42. It is activated whenever the SBC
requires a supply voltage for pin BAT14 (e.g. when V1 or V2 is on; see
Figure
control an external step-down voltage regulator to BAT14, to reduce power consumption in
low-power modes.
The SBC has a dedicated SENSE pin for dynamic monitoring of the battery contact in an
ECU. Connecting this pin in front of the polarity protection diode in an ECU provides an
early warning of a battery becoming disconnected.
The UJA1066 contains two independent voltage regulators supplied from pin BAT14.
Regulator V1 is intended to supply the microcontroller. Regulator V2 is reserved for the
high-speed CAN transceiver.
The voltage at V1 is continuously monitored to ensure a system reset signal is generated
when an undervoltage event occurs. A hardware reset is forced if the output voltage at V1
falls below one of the three programmable thresholds.
8). Otherwise pin SYSINH is left floating. Pin SYSINH can be used, for example, to
Rev. 02 — 5 May 2009
RSTN(CHT)
, the SBC immediately falls back to Fail-safe
RSTN(CLT)
High-speed CAN fail-safe system basis chip
, the SBC immediately enters Fail-safe
UJA1066
Figure 3
© NXP B.V. 2009. All rights reserved.
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