CS8147YTHA5 ON Semiconductor, CS8147YTHA5 Datasheet - Page 7

• Manufacturer Part Number: CS8147YTHA5
• Description: IC REG LDO DUAL ENABLE TO220-5
• Manufacturer: ON Semiconductor

Specifications of CS8147YTHA5

• Regulator Topology: Positive Fixed
• Voltage - Output: 10V, 5V
• Voltage - Input: 6 ~ 26 V
• Voltage - Dropout (typical): 0.5V @ 500mA, 1.5V @ 70mA
• Number Of Regulators: 2
• Current - Output: 500mA, 70mA
• Current - Limit (min): 550mA, -
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Through Hole
• Package / Case: TO-220-5 (Bent and Staggered Leads)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: CS8147YTHA5OS

the CS8147 is ideal for applications where a sleep mode is
required. Using the CS8147, a section of circuitry such as a
display and nonessential 5.0 V circuits can be shut down
under microprocessor control to conserve energy.
radio application where the display is powered by 10 V from
V
Neither output is required unless both the ignition and the
Radio On/OFF switch are on.
Stability Considerations
not require a compensation capacitor. However a
compensation capacitor connected between V
ground is required for stability in most applications.
three main characteristics of a linear regulator: start–up
delay, load transient response and loop stability.
availability, size and temperature constraints. A tantalum or
aluminum electrolytic capacitor is best, since a film or
ceramic capacitor with almost zero ESR can cause
instability. The aluminum electrolytic capacitor is the least
expensive solution, but, if the circuit operates at low
temperatures (–25 C to –40 C), both the value and ESR of
the capacitor will vary considerably. The capacitor
manufacturers data sheet usually provides this information.
applications circuit should work for most applications,
however it is not necessarily the optimized solution.
application, start with a tantalum capacitor of the
recommended value and work towards a less expensive
alternative part.
Step 1: Place the completed circuit with a tantalum
capacitor of the recommended value in an environmental
chamber at the lowest specified operating temperature and
monitor the outputs with an oscilloscope. A decade box
connected in series with the capacitor will simulate the
higher ESR of an aluminum capacitor. Leave the decade box
outside the chamber, the small resistance added by the
longer leads is negligible.
Step 2: With the input voltage at its maximum value,
increase the load current slowly from zero to full load while
observing the output for any oscillations. If no oscillations
are observed, the capacitor is large enough to ensure a stable
design under steady state conditions.
Step 3: Increase the ESR of the capacitor from zero using the
decade box and vary the load current until oscillations
appear. Record the values of load current and ESR that cause
the greatest oscillation. This represents the worst case load
conditions for the regulator at low temperature.
Step 4: Maintain the worst case load conditions set in step
3 and vary the input voltage until the oscillations increase.
OUT1
Since both outputs are controlled by the same ENABLE,
The test applications circuit diagram shows an automotive
The secondary output V
The output or compensation capacitor helps determine
The capacitor value and type should be based on cost,
The value for the output capacitor C2 shown in the test and
To determine acceptable value for C2 for a particular
and the Tuner IC is powered by 5.0 V from V
OUT2
is inherently stable and does
APPLICATION NOTES
OUT1
http://onsemi.com
OUT2
and
CS8147
.
7
This point represents the worst case input voltage
conditions.
Step 5: If the capacitor is adequate, repeat steps 3 and 4 with
the next smaller valued capacitor. A smaller capacitor will
usually cost less and occupy less board space. If the output
oscillates within the range of expected operating conditions,
repeat steps 3 and 4 with the next larger standard capacitor
value.
Step 6: Test the load transient response by switching in
various loads at several frequencies to simulate its real
working environment. Vary the ESR to reduce ringing.
Step 7: Raise the temperature to the highest specified
operating temperature. Vary the load current as instructed in
step 5 to test for any oscillations.
ESR is found for each output, a safety factor should be added
to allow for the tolerance of the capacitor and any variations
in regulator performance. Most good quality aluminum
electrolytic capacitors have a tolerance of 20% so the
minimum value found should be increased by at least 50%
to allow for this tolerance plus the variation which will occur
at low temperatures. The ESR of the capacitors should be
less than 50% of the maximum allowable ESR found in step
3 above.
Calculating Power Dissipation in a
Dual Output Linear Regulator
regulator (Figure 16) is
where:
permissible value of R
package section of the data sheet. Those packages with
R
the die temperature below 150 C.
dissipate the heat generated by the IC, and an external
heatsink will be required.
P D(max) + V IN(max) * V OUT1(min) I OUT1(max) )
Once the minimum capacitor value with the maximum
The maximum power dissipation for a dual output
V
V
V
I
application,
I
application, and
I
I
Once the value of P
The value of R
In some cases, none of the packages will be sufficient to
OUT1(max)
OUT2(max)
Q
OUT(max)
JA
IN(max)
OUT1(min)
OUT2(min)
’s less than the calculated value in equation 2 will keep
is the quiescent current the regulator consumes at
V IN(max) * V OUT2(min) I OUT2(max) ) V IN(max) IQ
is the maximum input voltage,
.
is the minimum output voltage from V
is the minimum output voltage from V
is the maximum output current, for the
is the maximum output current, for the
R QJA +
JA
can be compared with those in the
JA
D(max)
can be calculated:
150°C * T A
is known, the maximum
P D
OUT1
OUT2
(1)
(2)
,
,