CS5253-1GDPR5G ONSEMI [ON Semiconductor], CS5253-1GDPR5G Datasheet - Page 7

• Manufacturer Part Number: CS5253-1GDPR5G
• Description: 3.0 A LDO 5−Pin Adjustable Linear Regulator
• Manufacturer: ONSEMI [ON Semiconductor]

voltages from 1.26 V to 5.0 V at currents up to 3.0 A. The
regulator is protected against short circuits, and includes a
thermal shutdown circuit with hysteresis. The output, which
is current limited, consists of a PNP−NPN transistor pair and
requires an output capacitor for stability. A detailed procedure
for selecting this capacitor is included in the Stability
Considerations section.
V
efficiency. The collector of the power device is brought out
to the V
under high current loads. V
circuitry and the drive for the output NPN transistor.
V
voltage. Special care has been taken to ensure that there are
no supply sequencing problems. The output voltage will not
turn on until both supplies are operating. If the control voltage
comes up first, the output current will be limited to about three
milliamperes until the power input voltage comes up. If the
power input voltage comes up first, the output will not turn on
at all until the control voltage comes up. The output can never
come up unregulated.
the control and power inputs tied together. In this mode, the
dropout will be determined by the minimum control voltage.
Output Voltage Sensing
dedicated V
sensing of the output voltage. This feature can virtually
eliminate errors in the output voltage due to load regulation.
Regulation will be optimized at the point where the sense pin
is tied to the output.
Adjustable Operation
of 1.26 V to 5.0 V. An external resistor divider sets the output
voltage as shown in Figure 19. The regulator’s voltage
sensing error amplifier maintains a fixed 1.260 V reference
between the output pin and the adjust pin.
POWER
CONTROL
The CS5253−1 linear regulator provides adjustable
The CS5253−1 utilizes a two supply approach to maximize
The CS5253−1 can also be used as a single supply device with
The CS5253−1 five terminal linear regulator includes a
This LDO adjustable regulator has an output voltage range
The Resistor Divider Sets V
5.0 V
3.3 V
Figure 19. Typical Application Schematic.
POWER
1.260 V Reference Dropped Across R1.
Function
should be at least 1.0 V greater than the output
SENSE
V
V
THEORY OF OPERATION
pin to minimize internal power dissipation
CONTROL
POWER
DESIGN GUIDELINES
function. This allows for true Kelvin
CS5253−1
Adjust
CONTROL
V
SENSE
OUT
V
OUT
provides for the control
, With the Internal
R1
R2
APPLICATIONS NOTES
2.5 V
@ 3.0 A
http://onsemi.com
7
to flow to ground. This current creates a voltage across R2
that adds to the 1.260 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 should be taken into
account if precise adjustment of V
output voltage is set according to the formula:
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 over temperature. The divider resistors
should be placed physically as close to the load as possible.
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
specification of 6.0 V for the voltage difference between
V
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
the V
output capacitor as soon as the V
is large enough that the pass transistor conducts. As V
increases, the pass transistor will remain in dropout, and
current is passed to the load until V
Further increase in the supply voltage brings the pass
transistor out of dropout. In this manner, any output voltage
less than 13 V may be regulated, provided the V
V
V
limit to the regulated voltage as long as the V
differential of 6.0 V is not exceeded.
V
occurs. Short circuit conditions will result in the immediate
operation of the pass transistor outside of its safe operating
area. Overvoltage stresses will then cause destruction of the
pass transistor before overcurrent or thermal shutdown
circuitry can become active. Additional circuitry may be
required to clamp the V
than 6.0 V if fail safe operation is required. One possible
clamp circuit is illustrated in Figure 20; however, the design
of clamp circuitry must be done on an application by
application basis. Care must be taken to ensure the clamp
actually protects the design. Components used in the clamp
design must be able to withstand the short circuit condition
indefinitely while protecting the IC.
POWER
CONTROL
OUT
CONTROL
POWER
A resistor divider network R1 and R2 causes a fixed current
The term I
While not required, a bypass capacitor connected between
The CS5253−1 linear regulator has an absolute maximum
Power supply sequencing should be such that the
There is a possibility of damaging the IC when
POWER
V OUT + 1.260 V
differential is less than 6.0 V. In the case where
and V
− V
supply is brought up coincidentally with or before
and V
ADJ
supply. This allows the IC to begin charging the
OUT
OUT
× R2 represents the error added by the adjust
POWER
is greater than 6.0 V if a short circuit
. However, the IC may be used to regulate
POWER
are shorted, there is no theoretical
R1 ) R2
R1
to V
POWER
) R2
OUT
OUT
OUT
to V
differential to less
is necessary. The
I ADJ
is in regulation.
POWER
OUT
differential
POWER
to V
POWER
OUT
to