BL2046

conversion rate of the device. During the sample period, the source must charge the internal

sampling capacitor . After the capacitor has been fully charged, there is no further input current.

The rate of charge transfer from the analog source to the converter is a function of conversion rate.

TABLE 1. Input Configuration (DIN), Single-Ended Reference Mode (SER/

high).

low).

Internal Reference

The BL2046 has an internal 2.5V voltage reference that can be turned on or off with the control bit,

for battery monitoring, temperature measurement, and for using the auxiliary input. Optimal touch

screen performance is achieved when using the differential mode.

Reference Input

The voltage difference between +REF and –REF sets the analog input range. The BL2046

the reference input and its wide voltage range. As the reference voltage is reduced, the analog

voltage weight of each digital output code is also reduced. This is often referred to as the LSB

size and is equal to the reference voltage divided by 4096 in 12-bit mode. Any offset or gain error

inherent in the ADC appears to increase, in terms of LSB size, as the reference voltage is reduced.

With a lower reference voltage, more care must be taken to provide a clean layout including

adequate bypassing, a clean power supply, a low-noise reference, and a low-noise input signal.

portion of the BL2046. Therefore, the input current is very low.

There is also a critical item regarding the reference when making measurements while the switch

drivers are ON. For this discussion, it is useful to consider the typical application of the BL2046.

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