SP6205EM5-L-3-3-TR Datasheet, PDF (11/15 Pages) Exar Corporation – 300mA/500mA Low Noise CMOS LDO Regulators

SP6203 / SP6205
300mA/500mA Low Noise CMOS LDO Regulators
After calculation, we find that in such an
application (SP6205) the regulator is limited to
260.6mA. Doing the same calculations for the
300mA LDO (SP6203) will limit the regulator’s
output current to 260.9mA.
Also, taking advantage of the very low dropout
voltage characteristics of the SP6203/6205,
power dissipation can be reduced by using the
lowest possible input voltage to minimize the
input-to-output drop.
ADJUSTABLE REGULATOR APPLICATIONS
The SP6203/6205 can be adjusted to a specific
output voltage by using two external resistors
(see functional diagram). The resistors set the
output voltage based on the following
equation:
V_OUT = V_REF *(R1/R2 + 1)
Resistor values are not critical because ADJ
(adjust) has a high input impedance, but for
best performance use resistors of 470KΩ or
less. A bypass capacitor from ADJ to V_OUT
provides improved noise performance.
DUAL-SUPPLY OPERATION
When used in dual supply systems where the
regulator load is returned to a negative
supply, the output voltage must be diode
clamped to ground.
LAYOUT CONSIDERATIONS
The primary path of heat conduction out of the
package is via the package leads. Therefore,
careful considerations have to be taken into
account:
1) Attaching the part to a larger copper
footprint will enable better heat transfer from
the device, especially on PCB’s where there
are internal ground and power planes.
2) Place the input, output and bypass
capacitors close to the device for optimal
transient response and device behavior.
3) Connect all ground connections directly to
the ground plane. In case there’s no ground
plane, connect to a common local ground point
before connecting to board ground.
Such layouts will provide a much better
thermal conductivity (lower θ_JA) for, a higher
maximum allowable power dissipation limit.
© 2012 Exar Corporation
11/14
Rev. 2.0.0