5

The CS5201(adjustable version) develops a 1.25V

reference voltage between the Sense pin and the Adjust

pin (Figure 4).

Placing a resistor between these two

terminals causes a constant current to flow though R1

and down thouth R2 to set the output voltage. In general

R1 is chosen so that this current is the specified minimum

load current of 5 mA. The current out of the Adjust pin is

small, typically 50

A and it adds to the current from R1.

For best regulation the top of the resistor divider should

be connected directly to the Sense pin.

In normal operation CS5201 family does not need any

protection diodes between the adjustment pin and the

output and from the output to the input to prevent die

overstress.

Internal resistors are limiting the internal

current paths on the ADJ pin. Therefore even with bypass

capacitors on the adjust pin no protection diode is

needed to ensure device safety under short-circuit

conditions. The Adjust pin can be driver on a transient

basis

7V with respect to the output without any device

degradation.

pin is not usually needed. Microsecond surge currents of

50A to 100A can be handled by the internal diode

between the Output pin and V

pin of the device.

POWER

Output Voltage

Protection Diodes

In normal operations it is difficult to get those values of

surge currents even with the use of large output

capacitances. Only with high value output capacitors,

such as 1000

F to 5000

F and the V

pin is

POWER

instantaneously shorted to ground, damage can occour.

A diode from output to input is recommended (Figure 5).

If CS5201 is connected as a single supply device with the

control and power input pins shorted together the internal

diode between the output and the power input pin will

protect the control input pin.

The CS5201 series have internal power and thermal

limiting circuitry designed to protect the device under

overload conditions.

However maximum junction

temperature ratings should not be exceeded under

continuous normal load conditions. Careful consideration

must be given to all sources of thermal resistance from

junction to ambient, including junction-to-case, case-to-

heat sink interface and heat sink resistance itself.

Junction temperature of the Control section can run up to

125

. Junction temperature of the Power section can

run up to 150

.

Thermal Considerations

CONTROL

CONTROL

R2

R2

R1

R1

D1

D2

CS5201

CS5201

ADJ

ADJ

POWER

POWER

OUTPUT

OUTPUT

SENSE

SENSE

Figure 4. Setting Output Voltage

V

=

V

(1+R2/R1)+

I

R2

ADJ

OUT

REF

Figure 5. Optional Clamp Diodes Protect Against Input

Crowbar Circuits

+

+

+

+

+

+

CS-5201 1Amp Low Dropout Positive Voltage Regulator