NCP59300, NCV59300 Series
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APPLICATIONS INFORMATION
Output Capacitor and Stability
The NCP59300 series requires an output capacitor for
stable operation. The NCP59300 series is designed to
operate with ceramic output capacitors. The recommended
output capacitance value is 47 mF or greater. Such capacitors
help to improve transient response and noise reduction at
high frequency.
Input Capacitor
An input capacitor of 1.0 mF or greater is recommended
when the device is more than 4 inches away from the bulk
supply capacitance, or when the supply is a battery. Small,
surface−mount chip capacitors can be used for the
bypassing. The capacitor should be place within 1 inch of
the device for optimal performance. Larger values will help
to improve ripple rejection by bypassing the input of the
regulator, further improving the integrity of the output
voltage.
Minimum Load Current
The NCP59300 regulator is specified between finite
loads. A 10 mA minimum load current is necessary for
proper operation.
Error Flag
Some NCP59300 series members feature an error flag
circuit that monitors the output voltage and signals an error
condition when the voltage is 5% below the nominal output
voltage. The error flag is an open−collector output that can
sink up to 5 mA typically during a VOUT fault condition.
The FLG output is overload protected when a short circuit
of the pullup load resistor occurs in the application. This is
guaranteed in the full range of FLG output voltage Max
ratings (see Max Ratings table). Please be aware operation in
this mode is not recommended, power dissipated in the device
can impact on output voltage precision and other device
characteristics.
Enable Input
Some NCP59300 series members also feature an enable
input for on/off control of the device. It’s shutdown state
draws “zero” current from input voltage supply (only
microamperes of leakage). The enable input is TTL/CMOS
compatible for simple logic interface, but can be connected
up to VIN.
Overcurrent and Reverse Output Current Protection
The NCP59300 regulator is fully protected from damage
due to output current overload conditions. When NCP59300
output is overloaded, Output Current limiting is provided.
This limiting is linear; output current during overload
conditions is constant. These features are advantageous for
powering FPGAs and other ICs having current consumption
higher than nominal during their startup.
Thermal shutdown disables the NCP59300 device when
the die temperature exceeds the maximum safe operating
temperature.
When NCP59300 is disabled and (VOUT – VIN) voltage
difference is less than 6.5 V in the application, the output
structure of these regulators is able to withstand output
voltage (backup battery as example) to be applied without
reverse current flow. Of course the additional current
flowing through the Feedback resistor divider inside the
NCP59300 Fixed voltage devices (30 mA typically at
nominal output voltage) needs to be included in the backup
battery discharging calculations.
Thermal Considerations
The power handling capability of the device is limited by
the maximum rated junction temperature (125C). The PD
total power dissipated by the device has two components,
Input to output voltage differential multiplied by Output
current and Input voltage multiplied by GND pin current.
PD+ǒVIN *VOUTǓ@IOUT )VIN @IGND (eq. 1)
The GND pin current value can be found in Electrical
Characteristics table and in Typical Characteristics graphs.
The Junction temperature TJ is
TJ+TA)PD@RqJA (eq. 2)
where TA is ambient temperature and RqJA is the Junction to
Ambient Thermal Resistance of the NCP/NCV59300
device mounted on the specific PCB.
To maximize efficiency of the application and minimize
thermal power dissipation of the device it is convenient to
use the Input to output voltage differential as low as possible.
The static typical dropout characteristics for various
output voltage and output current can be found in the Typical
Characteristics graphs.