AN2615 datasheet(12/37 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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12 / 37 page

Characteristics of different slope converters

AN2615

12/37

6.2

Dual-slope converter

Figure 7.

Dual-slope converter circuit diagram

6.2.1

Dual-slope converter timing diagram

As shown in Figure 8 a dual-slope ADC has a charging phase followed by a fixed rate

discharging phase.

Figure 8.

Dual-slope converter timing diagram

The advantage of a dual-slope ADC is that it is not dependent on the correction factor for the

R*C product. However, the input offset voltage problem still persists and this ADC also

requires a dual supply op-amp to be able to measure positive and negative voltages.

out

gnd

clk

cmp

Control logic

enbl

clk

Counter

ctr

clk

-Vin

Vref

Vin1

Vin2

-Vref

Charging phase

Fixed-rate discharge

Vin

Vref

Tcharge

Tdischarge

Time

AN2615 Datasheet(PDF) 12 Page - STMicroelectronics