MC33263 Datasheet, PDF (4/12 Pages) ON Semiconductor – Ultra Low Noise 150 mA Low Dropout Voltage Regulator with ON/OFF Control

MC33263
DEFINITIONS
Load Regulation – The change in output voltage for a
change in load current at constant chip temperature.
Dropout Voltage – The input/output differential at which
the regulator output no longer maintains regulation against
further reductions in input voltage. Measured when the
output drops 100 mV below its nominal value (which is
measured at 1.0 V differential), dropout voltage is affected
by junction temperature, load current and minimum input
supply requirements.
Output Noise Voltage – The RMS AC voltage at the
output with a constant load and no input ripple, measured
over a specified frequency range.
Maximum Power Dissipation – The maximum total
dissipation for which the regulator will operate within
specifications.
Quiescent Current – Current which is used to operate the
regulator chip and is not delivered to the load.
Line Regulation – The change in input voltage for a
change in the input voltage. The measurement is made under
conditions of low dissipation or by using pulse techniques
such that the average chip temperature is not significantly
affected.
Line Transient Response – Typical over– and
undershoot response when input voltage is excited with a
given slope.
Thermal Protection – Internal thermal shutdown
circuitry is provided to protect the integrated circuit in the
event that the maximum junction temperature is exceeded.
When activated, typically 150°C, the regulator turns off.
This feature is provided to prevent catastrophic failures from
accidental overheating.
Maximum Package Power Dissipation – The maximum
package power dissipation is the power dissipation level at
which the junction temperature reaches its maximum value
i.e. 125°C. The junction temperature is rising while the
difference between the input power (VCC X ICC) and the
output power (Vout X Iout) is increasing.
Depending on ambient temperature, it is possible to
calculate the maximum power dissipation, maximum load
current or maximum input voltage (see Application Hints:
Protection).
The maximum power dissipation supported by the device
is a lot increased when using appropriate application design.
Mounting pad configuration on the PCB, the board material
and also the ambient temperature are affected the rate of
temperature rise. It means that when the IC has good thermal
conductivity through PCB, the junction temperature will be
“low” even if the power dissipation is great.
The thermal resistance of the whole circuit can be
evaluated by deliberately activating the thermal shutdown
of the circuit (by increasing the output current or raising the
input voltage for example).
Then you can calculate the power dissipation by
subtracting the output power from the input power. All
variables are then well known: power dissipation, thermal
shutdown temperature (150°C for MC33263) and ambient
temperature.
APPLICATION HINTS
Input Decoupling – As with any regulator, it is necessary
to reduce the dynamic impedance of the supply rail that
feeds the component. A 1 mF capacitor either ceramic or
tantalum is recommended and should be connected close to
the MC33263 package. Higher values will correspondingly
improve the overall line transient response.
Output Decoupling – Thanks to a novel concept, the
MC33263 is a stable component and does not require any
Equivalent Series Resistance (ESR) neither a minimum
output current. Capacitors exhibiting ESRs ranging from a
W W few m up to 3 can thus safely be used. The minimum
m decoupling value is 1 F and can be augmented to fulfill
stringent load transient requirements. The regulator accepts
ceramic chip capacitors as well as tantalum devices.
Noise Performances – Unlike other LDOs, the MC33263
is a true low–noise regulator. With a 10 nF bypass capacitor,
m it typically reaches the incredible level of 25 VRMS overall
noise between 100 Hz and 100 kHz. To give maximum
insight on noise specifications, ON Semiconductor includes
spectral density graphics as well as noise dependency versus
bypass capacitor.
The bypass capacitor impacts the start–up phase of the
MC33263 as depicted by the data–sheet curves. A typical
1 ms settling time is achieved with a 10 nF bypass capacitor.
However, thanks to its low–noise architecture, the
MC33263 can operate without bypass and thus offers a
m typical 20 s start–up phase. In that case, the typical output
m noise stays lower than 65 VRMS between 100 Hz –
100 kHz.
Protections – The MC33263 hosts several protections,
conferring natural ruggedness and reliability to the products
implementing the component. The output current is
internally limited to a minimum of 175 mA while
temperature shutdown occurs if the die heats up beyond
150°C. These value lets you assess the maximum
differential voltage the device can sustain at a given output
current before its protections come into play.
The maximum dissipation the package can handle is given
by:
+ Pmax
TJmax – TA
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