NCV5171EDR2G ON Semiconductor, NCV5171EDR2G Datasheet - Page 16

• Manufacturer Part Number: NCV5171EDR2G
• Description: IC REG BOOST 1.5A 280KHZ 8-SOIC
• Manufacturer: ON Semiconductor
• Type: Step-Up (Boost), Inverting, Flyback, Forward Converter, Sepicr

Specifications of NCV5171EDR2G

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Current - Output: 1.5A
• Frequency - Switching: 280kHz
• Voltage - Input: 2.7 ~ 30 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Mounting Style: SMD/SMT
• Operating Temperature Range: - 40 C to + 150 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Power - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

where:
whether the NCV5171/73 can be used in an application is
settled. If T
allowable junction temperature, the NCV5171/73 is not
suitable for that application.
possible means of reducing the junction temperature.
Perhaps another converter topology could be selected to
reduce the switch current. Increasing the airflow across the
surface of the chip might be considered to reduce T
Circuit Layout Guidelines
important for proper operation. Rapidly switching currents
combined with trace inductance generates voltage
T J + T A )(P D q JA )
T
T
P
q
For the NCV5171/73, q
Once the designer has calculated T
If T
In any switching power supply, circuit layout is very
A
D
JA
J
= IC or FET junction temperature (°C);
= ambient temperature (°C);
= power dissipated by part in question (W);
= junction−to−ambient thermal resistance (°C/W).
J
approaches 150°C, the designer should consider
J
exceeds 150°C, the absolute maximum
JA
=165°C/W.
J
, the question of
A
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.
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1.
2.
3.
transitions that can cause problems. Therefore the following
guidelines should be followed in the layout.
In boost circuits, high AC current circulates within the
loop composed of the diode, output capacitor, and
on−chip power transistor. The length of associated
traces and leads should be kept as short as possible. In
the flyback circuit, high AC current loops exist on both
sides of the transformer. On the primary side, the loop
consists of the input capacitor, transformer, and
on−chip power transistor, while the transformer,
rectifier diodes, and output capacitors form another
loop on the secondary side. Just as in the boost circuit,
all traces and leads containing large AC currents
should be kept short.
Separate the low current signal grounds from the
power grounds. Use single point grounding or ground
plane construction for the best results.
Locate the voltage feedback resistors as near the IC as
possible to keep the sensitive feedback wiring short.
Connect feedback resistors to the low current analog
ground.