AS1376 datasheet(11/20 Pages) AMSCO

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AS1376

Datasheet - Detailed Descr i pti on

8.1 Output Voltages

Standard products are factory-set with output voltages from 0.5V to 2.2V. A two-digit suffix of the part number identifies the nominal output (see

Ordering Information on page 18). Non-standard devices are available.

For more information contact: http://www.austriamicrosystems.com/contact

8.2 Advantages of Dual Supply Architecture vs Traditional Single Supply Approach

Compared to the traditional single supply approach, employing a P-channel series pass MOSFET, the dual rail architecture ensures improved

performances in a LDO when operating at very low input voltages below the threshold of the internal series power N-channel MOSFET. The

extra supply voltage at VBIAS (VBIAS > VIN) ensures that the N-channel MOSFET always operates above its threshold voltage.

Figure 18 shows simplified block diagrams of single supply P-channel LDO and dual rail N-channel series pass architectures.

Figure 18. Single vs. Dual Supply

The P-channel LDO uses a PMOS output transistor connected in a common source configuration. During regulation, the P-channel gate-source

voltage moves between VIN and GND as the load demands. The dual supply approach is based on an N-channel output transistor in common

drain configuration where the source is connected to the regulated output. During regulation, the N-channel gate source voltage increases from

VOUT to VBIAS as the load demands. As the drain voltage is not shared with the remaining blocks of the circuit, its value can be chosen

independently. The N-channel source follower design allows improved efficiency and dropout at low input voltages and provides faster load

transient response.

Bandgap

error

amplifier

PMOS

core

blocks

VIN

Bandgap

error

amplifier

NMOS

core

blocks

VIN

VBIAS

VOUT

Single Supply

Dual Supply

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