2010 Microchip Technology Inc. DS22051D-page 19
MCP1801
Junction Temperature Estimate
To estimate the internal junction temperature, the
calculated temperature rise is added to the ambient or
offset temperature. For this example, the worst-case
junction temperature is estimated in the following table.
Maximum Package Power Dissipation at +25°C
Ambient Temperature
6.4 Voltage Reference
The MCP1801 can be used not only as a regulator, but
also as a low quiescent current voltage reference. In
many microcontroller applications, the initial accuracy
of the reference can be calibrated using production test
equipment or by using a ratio measurement. When the
initial accuracy is calibrated, the thermal stability and
line regulation tolerance are the only errors introduced
by the MCP1801 LDO. The low cost, low quiescent
current, and small ceramic output capacitor are all
advantages when using the MCP1801 as a voltage
reference.
FIGURE 6-2: Using the MCP1801 as a
Voltage Reference.
6.5 Pulsed Load Applications
For some applications, there are pulsed load current
events that may exceed the specified 150 mA
maximum specification of the MCP1801. The internal
current limit of the MCP1801 will prevent high peak
load demands from causing non-recoverable damage.
The 150 mA rating is a maximum average continuous
rating. As long as the average current does not exceed
150 mA nor the maximum power dissipation of the
packaged device, pulsed higher load currents can be
applied to the MCP1801
. The typical current limit for
the MCP1801 is 300 mA (T
A
+25°C).
T
J
=T
JRISE
+ T
A(MAX)
T
J
= 81.42°C
SOT-23-5 (256°C/Watt = R
JA
)
P
D(MAX)
= (85°C - 25°C) / 256°C/W
P
D(MAX)
= 234 milli-Watts
PIC
®
MCP1801
GND
V
IN
C
IN
1µF
C
OUT
1µF
Bridge Sensor
V
OUT
V
REF
ADO
AD1
Ratio Metric Reference
25 µA Bias
Microcontroller
