MAS6512 datasheet(2/32 Pages) MAS

2 / 32 page

DA6512.003

2 December, 2016

2 (32)

BLOCK DIAGRAM

Figure 1. MAS6512 block diagram

FUNCTIONAL DESCRIPTION

MAS6512 can interface both single and dual

capacitance sensors. Single capacitance sensors

should be connected between the CS and the CC

inputs. The second capacitor of a dual capacitance

sensor should be connected between the CR and

the CC inputs.

A Capacitance-to-Digital Converter (CDC) converts

the input capacitances into a 16-bit output word

(code). The converter front-end can be configured

either for capacitance difference (CS-CR) or

capacitance ratio (CS-CR)/CS measurement mode.

The ratio mode offers pre-linearization for sensor

signals CS(x) being proportional to ~1/x such as

pressure sensor signals (x=pressure).

Converter resolution is selected by the over

sampling

ratio

(OSR)

setting.

Higher

OSR

corresponds to higher resolution but also longer

conversion time.

There are two internal 22pF capacitance matrices

connected to the CS and the CR inputs. These

matrices are used for sensor offset calibration and

are programmable in 8-bit steps (86fF/step).

The gain is programmable with 8-bits resolution and

sets

the

input

range

for

sensor

changing

capacitance

C=CS MAX-CS_MIN.

MAS6512 includes an internal temperature sensor

for

temperature

compensation

purposes.

multiplexer in the front-end is used to select the

external capacitive sensor, the internal temperature

sensor or an internal band gap reference voltage in

the VDD level monitoring mode.

Trim and calibration coefficients can be stored in

the 256-bit EEPROM memory. In normal mode the

stored trim values for the oscillator frequency, offset

capacitance and gain are automatically read from

the EEPROM memory in the beginning of each

conversion. However by using Trimming control

trimming values from the trimming registers instead

of EEPROM.

To avoid modification of the EEPROM by mistake

there is an EEPROM write enable bit in the

EEPROM Control Register which needs to be set

high (1) before any changes can be done to the

EEPROM.

MAS6512 has an internal clock oscillator making an

external clock unnecessary. To save power it’s

turned on only when a conversion is running. The

frequency is factory trimmed to 200 kHz using a 6-

bit register. An external clock, connected to the

OSC pin, can however be used when a specific test

mode is chosen. This may be necessary when

measuring larger capacitances which require a

slower clock frequency.

In temperature measurement mode it is necessary

to always use a regulated supply voltage. This is

achieved by enabling an internal 1.8V voltage

regulator. When enabled the internal regulator is

automatically turned on during conversion and off

when conversion has been finished. Note that the

internal regulator should be enabled only in the

temperature measurement mode but kept disabled

during capacitance and VDD monitoring modes.

MISO

SDA/MOSI

SCL/SCLK

MUX

TEMP



CONTROL

I2C /

SPI

EEPROM

CLK

OSC

XCS

XSPI

EOC

XCLR

VDD

GND

VREG

TEST

VREG

TEST1

TEST2

VDD

OSC

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