CS-5201 Datasheet, PDF (4/6 Pages) First Components International – 1Amp Low Dropout Positive Voltage Regulator

CS-5201 1Amp Low Dropout Positive Voltage Regulator
Application Information
The CS5201 is designed to make use of multiple power
supplies, to reduce the dropout voltage. One of the
advantages of the two supply approach is maximizing the
efficiency.0000000000000000000000000000000000000
The second supply is at least 1V greater than output
voltage and is providing the power for the control circuitry
and supplies the drive current to the NPN output
transistor. This allows the NPN output transistor to be
driven into saturation. For the control voltage the current
requirement is small equal to about 1% of the output
current. This drive current becomes part of the output
current. The maximum voltage on the Control pin is 12V.
The maximum voltage at the Power pin is 7V. By typing the
control and power inputs together the CS5201 can also
be operated as a single supply device. In single supply
operation the dropout will be determined by the minimum
control voltage.0000000000000000000000000000000000
Both the fixed and adjustable versions have remote sense
pins, permitting very accurate regulation of output
voltage. As a result, over an output current range of
100mA to 1A, the typical load regulation is less than 1mV.
For the fixed voltages the adjust pin is brought out
allowing the user to improve transient response by
bypassing the internal resistor divider. Optimum transient
response is provided using a capacitor in the range of
0.1 F to 1 F for bypassing the Adjust pin.000000000000
In addition to the enhancements mentioned, the
reference accuracy has been improved a factor of two
with a guaranteed initial tolerance of 1% at 25 and
1.6% accuracy over the full temperature and load current
range.00000000000000000000000000000000000000000
Typical applications for the CS5201 include 3.3V to 2.5V
conversion with a 5V control supply, 5V to 4.2V
conversion with a 12V control supply or 5V to 3.6V
conversion with a 12V control supply. The device is fully
protected against overcurrent and overtemperature
conditions.0000000000000000000000000000000000000
5.0V
3.3V
CONTROL
POWER
SENSE
CS5201
OUTPUT
ADJ.
R1
R2
Rp.
LOAD
R
Figure 1. Conventional Load Sensing
5.0V
3.3V
CONTROL
POWER
SENSE
CS5201
OUTPUT
ADJ.
R1
R2
R
LOAD
Rp.
Figure 2. Remote Load Sensing
Grounding and Output Sensing
The CS5201 allows true Kelvin sensing for both the high
and low side of the load. As a result the voltage regulation
at the load can be easily optimized. Voltage drops due to
parasitic resistances between the regulator and the load
can be placed inside the regulation loop. The advantages
of remote sensing are illustrated in figures 1 through 3.
Figure 1 shows the device connected as a conventional 3
terminal regulator with the Sense lead connected directly
to the connections between the device and the load.
Trace A of figure 3 illustrates the effect of Rp.1000000000
Figure 2 shows the device connected to take advantage
of the remote sense feature. The Sense pin and the top
of the resistor divider are connected to the top of the
load; the bottom of the resistor divider is connected to
the bottom of the load. The effect on output regulation
can be seen in trace B of figure 3.0000000000000000000
It is important to note that the voltage drops due to Rp,
are not eliminated; they will add to the dropout voltage of
the regulator regardless. The CS5201 can control the
voltage at the load as long as the input-output voltage is
greater than the total of the dropout voltage of the device
plus the voltage drop across Rp,.0000000000000000000
(0IOUT)(RP)
A
VOUT
FIGURE 1
VOUT
B
FIGURE 2
IOUT
TIME
Figure 3. Remote Sensing Improves Load Regulation
Stability
The circuit design used in the CS5201 series requires the
use of an output capacitor as part of the device frequency
compensation. The addition of 150 F aluminum
electrolytic or a 22 F solid tantalum on the output will
ensure stability for all operating conditions.00000000000
4