XRP6275 Datasheet, PDF (7/11 Pages) Exar Corporation – 3A Ultra Low Dropout Voltage Regulator

XRP6275
3A Ultra Low Dropout Voltage Regulator
THEORY OF OPERATION
SINGLE RAIL INPUT VOLTAGE
The XRP6275’s ultra low input voltage allows
single rail operation from 2.625V down to
1.045V without requiring any extra biasing
voltage. This single input voltage range
provides easy conversions from industry
standard 1.1V, 1.2V, 1.35V, 1.5V, 1.8V and
2.5V power rails.
DROPOUT VOLTAGE
The dropout voltage is the input-to-output
differential voltage at which the XR6275
ceases to regulate against further reductions
in input voltage; this point occurs when the
input voltage approaches the output voltage.
The XRP6275 provides ultra low industry
leading dropout voltage performance making it
the perfect solution for high current extremely
tight input/output voltage conversions. This
extremely low dropout voltage allows high
efficiencies conversions.
Below tables illustrate the achievable
conversions for different load requirements for
the XRP6275.
3A
Output Voltage
VIN (V) 1.80
1.50
1.35
1.20
1.10
1.00
0.90
0.80
0.60
2.50
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
1.80
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
1.50
No
Yes
Yes
Yes
Yes
Yes
Yes
1.35
No
Yes
Yes
Yes
Yes
Yes
1.20
No
Yes
Yes
Yes
Yes
1.10
No
Yes
Yes
Yes
2A
Output Voltage
VIN (V) 1.80
1.50
1.35
1.20
1.10
1.00
0.90
0.80
0.60
2.50
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
1.80
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
1.50
Yes
Yes
Yes
Yes
Yes
Yes
Yes
1.35
Yes
Yes
Yes
Yes
Yes
Yes
1.20
No
Yes
Yes
Yes
Yes
1.10
No
Yes
Yes
Yes
1A
Output Voltage
VIN (V) 1.80
1.50
1.35
1.20
1.10
1.00
0.90
0.80
0.60
2.50
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
1.80
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
1.50
Yes
Yes
Yes
Yes
Yes
Yes
Yes
1.35
Yes
Yes
Yes
Yes
Yes
Yes
1.20
Yes
Yes
Yes
Yes
Yes
1.10
Yes
Yes
Yes
Yes
Note: Yellow indicates conversions that may be thermally
limited
The maximum output current available for a
given conversion is dependent on the
operating conditions and thermal performance
of DFN10/PCB (see note 1 on page 3).
SETTING THE OUTPUT VOLTAGE
The XRP6275 is an adjustable regulator that
can be programmed to any value between
0.6V and 2.4V using 2 external resistors, R1
and R2. The relationship between the resistors
and the output voltage is:
0.6 ¹
where V_OUT is the desired output voltage.
Sum of resistors R1 and R2 must meet the
following requirement:
1 2 ²⁰
INPUT AND OUTPUT CAPACITORS
The XRP6275 is designed to be stable for all
available types and values of output capacitors
greater than 4.7µF.
The required capacitance on the V_IN and V_OUT
pins strongly depends on the input supply
source
impedance;
the
minimum
recommended capacitor for VIN is 4.7µF. Low
ESR ceramic X5R and X7R capacitors are
recommended and should be placed as close
as possible to the pins for optimal
performance.
Because of the low voltages and high currents
supported by this device, typical values of
47uF for both input and output capacitors are
recommended when powering high speed
digital circuits.
ENABLE INPUT AND SHUTDOWN
The enable pin (EN) can be used to shut down
the XRP6275. Connecting this pin to ground
signal or to a voltage less than typical 0.55V
will completely turn off the regulator. Pulling
the EN above 0.67V enables the XRP6275.
Where EN is derived from VIN it must be
sequenced with respect to VIN as shown in the
application circuit. Where an independent
control signal is applied to EN, it must be
asserted high after VIN reaches its minimum
operating range.
The enable pin is a high impedance MOS input.
In order to allow the EN pin compatibility with
5V or 3.3V control signals, there is an internal
© 2015 Exar Corporation
7/11
Rev. 2.0.0