MCP1790T-3302E/DB Microchip Technology, MCP1790T-3302E/DB Datasheet - Page 19

• Manufacturer Part Number: MCP1790T-3302E/DB
• Description: High Voltage, LDO, 70 MA 3 SOT-223 T/R
• Manufacturer: Microchip Technology

Specifications of MCP1790T-3302E/DB

• Regulator Topology: Positive Fixed
• Voltage - Output: 3.3V
• Voltage - Input: 6 ~ 30 V
• Voltage - Dropout (typical): 0.7V @ 70mA
• Number Of Regulators: 1
• Current - Output: 70mA (Min)
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: SOT-223 (3 leads + Tab), SC-73, TO-261
• Number Of Outputs: 1
• Polarity: Positive
• Input Voltage Max: 30 V
• Output Voltage: 3.3 V
• Output Type: Fixed
• Dropout Voltage (max): 1.3 V at 70 mA
• Output Current: 70 mA
• Line Regulation: +/- 0.0002 % / V
• Load Regulation: +/- 0.2 %
• Voltage Regulation Accuracy: 2.5 %
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Limit (min): -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: MCP1790T-3302E/DBTR

5.3
Internal power dissipation, junction temperature rise,
junction temperature and maximum power dissipation
are calculated in the following example. The power
dissipation, as a result of ground current, is small
enough to be neglected.
5.3.1
5.3.1.1
The internal junction temperature rise is a function of
internal power dissipation and the thermal resistance
from junction to ambient for the application. The
thermal resistance from junction to ambient (Rθ
derived from an EIA/JEDEC standard for measuring
thermal resistance for small surface mount packages.
The EIA/JEDEC specification is JESD51-7, “High
Effective Thermal Conductivity Test Board for Leaded
Surface Mount Packages”. The standard describes the
test method and board specifications for measuring the
thermal resistance from junction to ambient. The actual
thermal resistance for a particular application can vary
depending on many factors, such as copper area and
thickness. Refer to AN792, “A Method to Determine
How Much Power a SOT23 Can Dissipate in an
Application”,
regarding this subject.
© 2008 Microchip Technology Inc.
Package:
Input Voltage:
LDO Output Voltages and Currents:
Maximum Ambient Temperature:
Internal Power Dissipation:
Internal Power dissipation is the product of the LDO
output current times the voltage across the LDO
(V
Package Type = SOT-223-5
IN
P
to V
T
LDO(MAX)
T
T
J(RISE)
T
JRISE
JRISE
Power Dissipation Example
A(MAX)
OUT
V
P
P
I
OUT
OUT
POWER DISSIPATION EXAMPLE
LDO
LDO
V
).
Device Junction Temperature Rise
IN
= P
= 955 milli-Watts x 62
= 59.2
(DS00792),
= 8V to 24V
= 5.0V
= 50 mA
= +40°C
= (V
= (24V - (0.98 x 5.0V)) x 50 mA
= 955 milli-Watts
TOTAL
°
IN(MAX)
C
x Rq
- V
JA
for
OUT(MIN)
more
°
C/Watt
) x I
information
OUT(MAX)
JA
) is
5.3.1.2
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 below.
5.3.1.3
5.4
For some applications, there are pulsed load current
events that may exceed the specified 70 mA maximum
specification of the MCP1790/MCP1791. The internal
current foldback feature of the MCP1790/MCP1791 will
prevent high peak load demands from causing
non-recoverable damage. The Current Foldback
feature of the device will limit the output voltage and
output current during pulsed applications. As the cur-
rent rises above the foldback current threshold, the out-
put voltage will decrease.
SOT-223-5 (62°C/Watt = Rθ
DDPAK-5 (32°C/Watt = Rθ
MCP1790/MCP1791
P
P
P
P
D(MAX)
D(MAX)
D(MAX)
D(MAX)
Pulsed Load Applications
T
T
J
J
Junction Temperature Estimate
Maximum Package Power
Dissipation at +40°C Ambient
Temperature
= T
= 99.2°C
= (125°C - 40°C) / 62°C/W
= 1.371 Watts
= (125°C - 40°C) / 32°C/W
= 2.656 Watts
JRISE
+ T
A(MAX)
JA
JA
)
)
DS22075A-page 19