Datasheet

LPC4370 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2013. All rights reserved.
Product data sheet Rev. 2 — 21 October 2013 136 of 150
NXP Semiconductors
LPC4370
32-bit ARM Cortex-M4/M0 microcontroller
13.8.1 Inverting single-ended circuit
For the inverting single-ended circuit only one op-amp is needed. A 1.24 V shunt voltage
reference is used for creating an offset voltage of 450 mV. The disadvantage is that the
signal output of the circuit is inverted. However, this can be easily solved in software by
subtracting the ADC output from 4095, which is the maximum value of the 12-bit result.
(2)
Fig 46. Inverting single-ended circuit for 12-bit ADCHS input
Vout Vcom
R4
R3 R4+
--------------------
1
R2
R1
-------
+


 Vin_pos
R2
R1
-------
–=
100 mV - 900 mV
V
com
V
out
5V
5 V
R3
R2
1.24 V
R1
R4
R5
Vin_pos
0 V - 800 mV (R1 = R2)
0 V - 3.3 V (R1 = 10 x R2)
to ADCHS_n
aaa-009655