Referent voltage generators

There are three stable voltage generators in PSoC microcontroller:

·         AGND

·         RefH

·         RefLo

AGND is ground voltage for analog components. Voltage values higher than AGND are considered as positive, while less are negative. PSoC microcontrollers have one-side power supply, so value of analog

ground is somewhere in between GND and VDD. AGND value is selected by user.

RefHi and RefLo represent referent higher and lower voltage, for AD and DA components. PSoC microcontrollers have a system that can generate several referent signal values AGND, RefHi and RefLo. This enables simple adjustment to different types of voltage sensors. Referent voltages are made from internal temperature stabilized bandgap voltage reference Vbg = 1.3V, supply voltage VDD or external signal as shown in the following table. PSoC microcontrollers are well adjusted to work with battery supply.

Ref Mux AGND [V] RefLo [V] RefHi [V]

Vdd/2 } Vbg 2.5/1.65 1.2/0.35 3.8/2.95

Vdd/2 } Vdd/2 2.5/1.65 0 5.0/3.3

Vbg } Vbg 1.3 0 2.6

1.6Vbg } 1.6Vbg 2.08 0 4.16

2Vbg } Vbg 2.6 1.3 3.9

2Vbg } P2[6] 2.6 1.6 3.6

P2[4] } Vbg 2.2 0.9 3.5

P2[4] } P2[6] 2.2 1.2 3.2