NCP59302DSADJR4G Datasheet, PDF (8/10 Pages) ON Semiconductor – 3.0 A, Very Low-Dropout (VLDO) Fast Transient Response Regulator series

NCP59302, NCV59302
APPLICATIONS INFORMATION
Output Capacitor and Stability
The NCP59302 device requires an output capacitor for
stable operation. The NCP59302 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 NCP59302 regulator is specified between finite
loads. A 10 mA minimum load current is necessary for
proper operation.
Enable Input
NCP59302 regulators 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 V_IN.
Overcurrent and Reverse Output Current Protection
The NCP59302 regulator is fully protected from damage
due to output current overload conditions. When NCP59302
output is overloaded, Output Current limiting is provided.
This limiting is linear; output current during overload
conditions is constant. The device is also capable to
withstand power−on or enable start−up with output shorted
to ground for the full Recommended Operating Conditions
range. These features are advantageous for powering
FPGAs and other ICs having current consumption higher
than nominal during their startup.
Thermal shutdown disables the NCP59302 device when
the die temperature exceeds the maximum safe operating
temperature.
When NCP59302 is disabled and (V_OUT – V_IN) 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.
Adjustable Voltage Design
The NCP/NCV59302 Adjustable voltage Device Output
voltage is set by the ratio of two external resistors as shown
in Figure 21.
The device maintains the voltage at the ADJ pin at 1.24 V
referenced to ground. The current in R2 is then equal to
1.24 V / R2, and the current in R1 is the current in R2 plus
the ADJ pin bias current. The ADJ pin bias current flows
from V_OUT through R1 into the ADJ pin.
The output voltage can be calculated using the formula
shown in Figure 21.
V_IN
+
C_IN
NCP59302
VIN VOUT
EN
ADJ
GND
V_OUT
R1 ⁺
C_OUT
47 mF,
Ceramic
R2
ǒ Ǔ _{VOUT + 1.24 V @}
1 ) ^R1
R2
) I_ADJ @ R1
Figure 21. Adjustable Voltage Operation
Thermal Considerations
The power handling capability of the device is limited by
the maximum rated junction temperature (125C). The P_D
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.
P_D + ^ǒV_IN * V_OUT^Ǔ @ I_OUT ) V_IN @ I_GND (eq. 1)
The GND pin current value can be found in Electrical
Characteristics table and in Typical Characteristics graphs.
The Junction temperature T_J is
T_J + T_A ) P_D @ R_qJA
(eq. 2)
where T_A is ambient temperature and R_qJA is the Junction to
Ambient Thermal Resistance of the NCP/NCV59302
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.
http://onsemi.com
8