MCP201
DS21730F-page 8
2007 Microchip Technology Inc.
TABLE 1-4:
FAULT / SLPS SLOPE
SELECTION DURING POR
TABLE 1-5:
FAULT / SLPS TRUTH TABLE
1.6
Internal Voltage Regulator
The MCP201 has a low drop-out voltage, positive
regulator capable of supplying 5.00 VDC ±5% at up to
50 mA of load current over the entire operating
temperature range. With a load current of 50 mA, the
minimum input-to-output voltage differential required
for the output to remain in regulation is typically +0.5V
(+1V maximum over the full operating temperature
range). Quiescent current is less than 1.0 mA, with a
full 50 mA load current, when the input-to-output
voltage differential is greater than +2V.
The regulator requires an external output bypass
capacitor for stability. The capacitor should be either a
ceramic or tantalum for stable operation over the
extended
temperature
range.
The
compensation
capacitor should range from 1.0 f – 22 f and have a
ESR or CSR of 0.4
Ω – 5.0Ω. The input capacitor, CF, in
Figure 1.4 should be on the order of 8 to 10 times larger
than the output capacitor, CG.
Designed for automotive applications, the regulator will
protect itself from reverse battery connections, double-
battery jumps and up to +40V load dump transients.
The voltage regulator has both short-circuit and
thermal shutdown protection built-in.
Regarding the correlation between VBAT, VREG and IDD,
voltage (VBAT) drops below the differential needed to
provide stable regulation, the output VREG will track the
input down to approximately 3.5V, at which point the
regulator will turn off. This will allow microcontrollers
with internal POR circuits to generate a clean arming of
the Power-on Reset trip point. The MCP201 will then
monitor VBAT and turn on the regulator when VBAT is
6.0V. The device will come up in either READY1 or
READY mode and will have to be transitioned to
Operational mode to re-enable data transmission.
In the start phase, VBAT must be at least 6.0V
Power-down mode, the VBAT monitor will be turned off.
The regulator has a thermal shutdown. If the thermal
protection circuit detects an overtemperature condition
regulator, it will shut down.
The regulator has an overload current limiting. During
a short-circuit, VREG is monitored. If VREG is lower than
3.5V, the regulator will turn off. After a thermal recovery
time, the VREG will be checked again. If there is no
short-circuit (VREG > 3.5V), the regulator will be
switched back on. The MCP201 will come up in either
READY1 or READY mode and will have to be
transitioned to Operational mode to re-enable data
transmission.
The accuracy of the voltage regulator, when using a
pass transistor, will degrade due to the extra external
components needed. All performance characteristics
should be evaluated on every design.
FAULT/SLPS
Slope Shaping
HNormal
LAlternate(1)
Note 1:
This mode does not conform to LIN bus
specification version 1.3, but might be
used for K-line applications.
Note:
This pin is ‘0’ whenever the internal circuits
have detected a short or thermal excursion
and have disabled the LIN output driver.
Note:
Every time TX is toggled, a Fault condition
will occur for the length of time, depending
on the bus load. The Fault time is equal to
the propagation delay.
TXD In
RXD Out
LIN Bus I/O
Thermal
Override
FAULT / SLPS Out
Comments
LH
VBAT
OFF
L
Bus shorted to battery
HH
VBAT
OFF
H
Bus recessive
L
GND
OFF
H
Bus dominant
H
L
GND
OFF
L
Bus shorted to ground
xx
VBAT
ON
L
Thermal excursion
Legend: x = don’t care