UJA1061TW PHILIPS [NXP Semiconductors], UJA1061TW Datasheet - Page 20

• Manufacturer Part Number: UJA1061TW
• Description: Low speed CAN/LIN system basis chip
• Manufacturer: PHILIPS [NXP Semiconductors]

Philips Semiconductors
6.5.2
The functionality of the pin EN is almost identical to that of
pin RSTN. The differences are:
Pin EN, active LOW, is used for emergency shut-down of
items such as external power components. During all reset
events when pin RSTN is pulled LOW the EN control bit
will be reset, pin EN will be pulled LOW and will stay LOW
after pin RSTN is released, Within the Normal mode and
Flash mode of the UJA1061, the microcontroller can set
the EN control bit via SPI again. This results in releasing
pin EN which then returns to HIGH-level. Based on this,
the EN signal also can be used as a general purpose
output when the system is running properly.
6.6
6.6.1
Besides the BAT14 supply pin (14 V), which is used to
supply voltage regulators V1 and V2, the UJA1061
provides a BAT42 supply pin (42 V) in order to support
42 V systems. The UJA1061 supports three power supply
architectures:
To be able to control the external DC/DC converter for a
single 42 V architecture or for connecting pin BAT 14 to a
voltage lower than 12 V (in order to achieve a higher
output current source capability of V1), SYSINH is HIGH
when V1 and/or V2 is present, and is floating in all other
cases.
In Sleep mode the SYSINH signal allows the external
DC/DC converter to be disabled if both voltage supply
outputs V1 and V2 are no longer needed. In this case the
UJA1061 is powered only via pin BAT42 and pin SYSINH
will float. In this situation, no input voltage is required at
pin BAT14.
2004 Mar 22
Output functionality only, not an input/output
EN output can only be released by the microcontroller
via an SPI access.
Single 42 V battery system
– pin BAT42 has to be connected to the 42 V battery
– pin BAT14 has to be connected to, for example, a
Single 14 V battery system
– both pins BAT14 and BAT42 have to be connected to
Two batteries (14 and 42 V) system
– BAT42 has to be connected to the 42 V battery
– BAT14 has to be connected to the 14 V battery.
Low speed CAN/LIN system basis chip
DC/DC converter (42 to 14 V or lower)
the 14 V battery
Power supplies
E
S
NABLE OUTPUT PIN
UPPORTED BATTERY SYSTEMS
EN
20
Whenever V1 and/or V2 is needed for the application,
pin SYSINH will be set HIGH again, providing the BAT42
voltage to the external DC/DC converter or any other
dedicated hardware.
6.6.2
Static battery monitoring is available at pin BAT42. With
prolonged low voltages on pin BAT42, the UJA1061 forces
a system reset and sets a dedicated Power-on reset flag in
the reset source code register. Fail-safe mode will be
entered, even if BAT14 is still connected.
The UJA1061 has a dedicated SENSE pin for dynamic
monitoring the battery contact of an electronic control unit.
As this SENSE pin is connected at the electronic control
unit input before the connection to the external reverse
current protection diode for pin BAT42, a fast detection of
a power-down, e.g. caused by a loose battery connector,
can be executed. The advantage is in the extra time for the
microcontroller to shut down properly before a system
reset occurs as a result of an undervoltage at V1.
6.6.3
The UJA1061 has two independent voltage regulators that
are supplied through the external BAT14 input pin. One
regulator (V1) is for the microcontroller and one
regulator (V2) is for the fault tolerant CAN-transceiver.
This dual regulator concept offers the following
advantages:
6.6.3.1
The V1 voltage regulator is targeted to supply the
application microcontroller. As well as this primary
function, the accuracy of this regulator makes it suitable to
supply the reference voltage for the analog-to-digital
converter of the microcontroller.
V1 voltage is monitored continuously in order to provide
the system reset signal when undervoltage situations
occur. Whenever V1 voltage falls below one of the two
programmable thresholds, a hardware reset will be forced.
All noise coming from the microcontroller load is
decoupled from the bus lines
The UJA1061 can always support the complete
fault-tolerant physical layer, including the biasing, even
if the microcontroller is not present (V1 short-circuited or
load is too high)
The possibility of choosing a supply voltage for the
microcontroller that is lower than 5,V, i.e. 3.3, 3 or 2.5 V
according to version.
S
V
TATIC AND DYNAMIC BATTERY MONITORING
OLTAGE REGULATORS
V1 voltage regulator
V1
AND
Objective specification
V2
UJA1061