cs5253b-1-d ON Semiconductor, cs5253b-1-d Datasheet - Page 7

• Manufacturer Part Number: cs5253b-1-d
• Description: 3.0 A Ldo 5-pin Adjustable Linear Regulator With Remote Sense Applications
• Manufacturer: ON Semiconductor

Remote Sense
CS5253B−1 but some care must be paid to the layout and
positioning of the filter capacitors around the part. The
ground side of the input capacitors on the +5.0 V and +3.3 V
lines and the local V
on the IC output must be tied close to the ground connected
resistor voltage divider feedback network. The top resistor
of the divider must be connected directly to the V
Adjustable Operation
range of 1.25 V to 5.0 V. An external resistor divider sets the
output voltage as shown in Figure 20. The regulator’s
voltage sensing error amplifier maintains a fixed 1.25 V
reference between the output pin and the adjust pin.
current to flow to ground. This current creates a voltage
across R2 that adds to the 1.25 V across R1 and sets the
overall output voltage. The adjust pin current (typically
50 mA) also flows through R2 and adds a small error that
5.0 V
Remote sense operation can be easily obtained with the
This LDO adjustable regulator has an output voltage
A resistor divider network R1 and R2 causes a fixed
Figure 20. Typical Application Schematic. The
Resistor Divider Sets V
3.3 V
+5.0 V
+3.3 V
1.260 V Reference Dropped Across R1.
GND
V
V
CONTROL
POWER
DESIGN GUIDELINES
OUT
CS5253B−1
Adjust
−to−ground local output capacitor
+
10 mF
OUT
V
SENSE
V
, With the Internal
OUT
+
100 mF
R1
R2
V
V
CONTROL
POWER
Local
Connections
Figure 19. Remote Sense
SENSE
CS5253B−1
2.5 V
@ 3.0 A
http://onsemi.com
CS5253B−1
pin
V
7
SENSE
V
ADJ
OUT
of the regulator. This will establish the stability of the part.
This capacitor−divider resistor connection may then be
connected to ground remotely at the load, giving the ground
portion remote sense operation.
connection, giving the feedback remote sense operation.
The remote sense lines should be Kelvin connected so as to
eliminate the effect of load current voltage drop. An optional
bypass capacitor may be used at the load to reduce the effect
of load variations and spikes.
should be taken into account if precise adjustment of V
is necessary. The output voltage is set according to the
formula:
adjust pin current. R1 is chosen so that the minimum load
current is at least 10 mA. R1 and R2 should be of the same
composition for best tracking overtemperature.
the adjust pin and ground will improve transient response
and ripple rejection. A 0.1 mF tantalum capacitor is
recommended for “first cut” design. Value and type may be
varied to optimize performance vs. price.
Other Adjustable Operation Considerations
maximum specification of 6.0 V for the voltage difference
between V
to regulate voltages in excess of 6.0 V. The two main
considerations in such a design are the sequencing of power
supplies and short circuit capability.
V
before the V
charging the output capacitor as soon as the V
V
conducts. As V
remain in dropout, and current is passed to the load until
CONTROL
OUT
The V
The term I
While not required, a bypass capacitor connected between
The CS5253B−1 linear regulator has an absolute
Power supply sequencing should be such that the
differential is large enough that the pass transistor
V OUT + 1.25 V
124
SENSE
124
POWER
supply is brought up coincidentally with or
+
POWER
ADJ
33 mF
line can then be tied remotely at the load
POWER
and V
R2 represents the error added by the
supply. This allows the IC to begin
Remote
Connections
R
R
increases, the pass transistor will
OUT
DIS
DIS
R1 ) R2
. However, the IC may be used
R1
) R2
+
Optional
+Load
−Load
I ADJ
POWER
OUT
to