NCP1117ST285T3G ON Semiconductor, NCP1117ST285T3G Datasheet - Page 10

• Manufacturer Part Number: NCP1117ST285T3G
• Description: IC REG LDO 1A 2.85V SOT223
• Manufacturer: ON Semiconductor

Specifications of NCP1117ST285T3G

• Regulator Topology: Positive Fixed
• Voltage - Output: 2.85V
• Voltage - Input: Up to 20V
• Voltage - Dropout (typical): 1.07V @ 800mA
• Number Of Regulators: 1
• Current - Limit (min): 1A
• Operating Temperature: 0°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: 20 V
• Output Voltage: 2.85 V
• Output Type: Fixed
• Dropout Voltage (max): 1.1 V at 100 mA
• Output Current: 1 A
• Line Regulation: 0.8 mV
• Load Regulation: 3.8 mV
• Voltage Regulation Accuracy: 1 %
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: 0 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: NCP1117ST285T3GOS; NCP1117ST285T3GOS; NCP1117ST285T3GOSTR

Protection Diodes
diode paths that normally do not require protection when
used in the typical regulator applications. The first path
connects between V
surge current of about 15 A. Normal cycling of V
generate a current surge of this magnitude. Only when V
is shorted or crowbarred to ground and C
50 mF, it becomes possible for device damage to occur.
Under these conditions, diode D1 is required to protect the
device. The second path connects between C
it can withstand a peak surge current of about 150 mA.
Protection diode D2 is required if the output is shorted or
crowbarred to ground and C
required in the event that V
is greater than 50 mF. The peak current capability stated for
the internal diodes are for a time of 100 ms with a junction
temperature of 25°C. These values may vary and are to be
used as a general guide.
Load Regulation
load regulation; but since these are three terminal devices,
only partial remote load sensing is possible. There are two
conditions that must be met to achieve the maximum
available load regulation performance. The first is that the
top side of programming resistor R1 should be connected as
close to the regulator case as practicable. This will minimize
the voltage drop caused by wiring resistance RW + from
appearing in series with reference voltage that is across R1.
The NCP1117 family has two internal low impedance
Input
A combination of protection diodes D1 and D2 may be
The NCP1117 series is capable of providing excellent
C
in
Figure 25. Protection Diode Placement
+
3
NCP1117
1N4001
XTA
D1
out
1
R2
and V
in
2
adj
in
is shorted to ground and C
, and it can withstand a peak
is greater than 1.0 mF.
+
R1
C
adj
D2
1N4001
out
adj
is greater than
and V
in
Output
+
out
C
http://onsemi.com
cannot
out
, and
adj
in
10
The second condition is that the ground end of R2 should be
connected directly to the load. This allows true Kelvin
sensing where the regulator compensates for the voltage
drop caused by wiring resistance RW −.
Thermal Considerations
that is designed to protect the regulator in the event that the
maximum junction temperature is exceeded. When
activated, typically at 175°C, the regulator output switches
off and then back on as the die cools. As a result, if the device
is continuously operated in an overheated condition, the
output will appear to be oscillating. This feature provides
protection from a catastrophic device failure due to
accidental overheating. It is not intended to be used as a
substitute for proper heatsinking. The maximum device
power dissipation can be calculated by:
DPAK packages. Each package has an exposed metal tab
that is specifically designed to reduce the junction to air
thermal resistance, R
board copper as a heat dissipater. Figures 21 and 22 show
typical R
pattern using economical single sided 2.0 ounce copper
board material. The final product thermal limits should be
tested and quantified in order to insure acceptable
performance and reliability. The actual R
considerably from the graphs shown. This will be due to any
changes made in the copper aspect ratio of the final layout,
adjacent heat sources, and air flow.
Input
This series contains an internal thermal limiting circuit
The devices are available in surface mount SOT−223 and
C
in
+
qJA
3
values that can be obtained from a square
NCP1117
Figure 26. Load Sensing
XTA
P D +
1
qJA
, by utilizing the printed circuit
T J(max) * T A
2
R1
R qJA
R2
+
C
out
RW+
RW−
qJA
Output
can vary
Remote
Load