AN2615 datasheet(10/37 Pages) STMICROELECTRONICS

Part #	AN2615

Description	In general the ADC embedded in the ST7 microcontroller

PDF	37 Pages

Scroll/Zoom	100%

Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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10 / 37 page

Vout vs time diagram for different input voltages

AN2615

10/37

Vout vs time diagram for different input voltages

In Figure 4, we can see the relationship between the Vout and time for different input

voltages. From the figure, it is clear that the conversion time for a negative input voltage is

less than the time taken for a positive input voltage.

Figure 4.

Vout vs time for different input voltages

Tm1: for Vin < 0; Tm2: for Vin = 0; and Tm3: for Vin > 0 (where Tin1 < Tin2 < Tin3)

This ADC works for the range Vin <= V1 but if the input voltage is greater than V1 the direction of current I is

inverted and the capacitor starts charging in the opposite direction and conversion never takes place.

For negative voltage currents I, that depend on the difference V1 - Vin, is high, so the charging time for

negative voltages is less than the positive voltages.

Effective time Tm = T - T’

Vin < 0

Vin =0

Vin > 0

Vout

T1’

T2’ T1

T3’

Time (t)

AN2615 Datasheet(PDF) 10 Page - STMicroelectronics