ADP3301

–7–

REV. 0

It is not recommended to use solder mask or silkscreen on the

PCB traces adjacent to the ADP3301’s pins since it will increase

the junction to ambient thermal resistance of the package.

Shutdown Mode

Applying a TTL high signal to the shutdown pin, or tying it to

the input pin, will turn the output ON. Pulling the shutdown

pin low, or tying it to ground, will turn the output OFF. In

shutdown mode, quiescent current is reduced to less than 1

µA.

Error Flag Dropout Detector

The ADP3301 will maintain its output voltage over a wide

range of load, input voltage and temperature conditions. If, for

example, regulation is lost by reducing the supply voltage below

the combined regulated output and dropout voltages, the ERRor

flag will be activated. The ERR output is an open collector,

which will be driven low.

Once set, the ERRor flag’s hysteresis will keep the output low

until a small margin of operating range is restored either by

raising the supply voltage or reducing the load.

APPLICATION CIRCUITS

Crossover Switch

The circuit in Figure 21 shows that two ADP3301s can be used

to form a mixed supply voltage system. The output switches

between two different levels selected by an external digital input.

Output voltages can be any combination of voltages from the

Ordering Guide.

Higher Output Current

The ADP3301 can source up to 100 mA without any heatsink

or pass transistor. If higher current is needed, an appropriate

pass transistor can be used, as in Figure 22, to increase the

output current to 1 A.

Step-Up/Step-Down Post Regulator

The circuit in Figure 23 provides a high precision, low dropout

regulated output voltage. It significantly reduces the ripple from

a switching regulator. The ADP3000 used in this circuit is a

switching regulator in the step-up configuration.

D1

1N5817

C2

100µF

10V

L1

6.8µH

R1

120

Ω

R2

19.6k

Ω

1%

R3

10k

Ω

1%

ADP3301-3.3

IN

OUT

GND

C3

2.2µF

3.3V @ 100mA

C1

100µF

10V

ADP3000-ADJ

SW1

GND

SW2

FB

Figure 23. Step-Up/Step-Down Post Regulator

OUTPUT SELECT

5V

0V

C2

0.47µF

IN

OUT

GND

SD

ADP3301-5.0

+

+

IN

OUT

GND

SD

ADP3301-3.3

C1

1.0µF

Figure 21. Crossover Switch

MJE253*

C2

10µF

C1

47µF

R1

50

Ω

*AAVID531002 HEAT SINK IS USED

IN

OUT

ERR

GND

SD

ADP3301-5

Figure 22. High Output Current Linear Regulator