Data Sheet

ADuCM350

Rev. A | Page 5 of 40

DAC/RCF/PGA Specifications

Table 3. DAC/PGA/RCF Specifications

Min

Typ

Max

Unit

Test Conditions/Comments

DAC

Output Range

−600

+600

mV

As seen by sensor

Resolution

12

Bits

Integral Nonlinearity (INL)

±0.85

LSB

Measured at an output of the excitation

loop, using gain = 1 and default DAC clock

(16 MHz ÷ 49 DAC clock speed)

Differential Nonlinearity (DNL)

−1

+1

LSB

Measured at an output of the excitation

loop, using gain = 1 and default DAC clock

(16 MHz ÷ 49 DAC clock speed)

Full-Scale Error

Positive

±0.2

% FSR

PGA (gain = 1), measured at an output of

the excitation loop, DAC code = 0xE00

±1

% FSR

PGA (gain = 0.025), measured at an output

of the excitation loop, DAC code = 0xE00

Negative

±0.2

% FSR

PGA (gain = 1), measured at an output of

the excitation loop, DAC code = 0x200

±1

% FSR

PGA (gain = 0.025), measured at an output

of the excitation loop, DAC code = 0x200

Offset Error, Midscale

±1

mV

PGA (gain = 1 or gain = 0.025), measured

at an output of the excitation loop across

RCAL

Clocking Frequency

280.7

320

380.95

kHz

PROGRAMMABLE GAIN AMPLIFIER (PGA)

Gain from PGA in State 0

1

Covered by DAC full-scale error measured

on an output of the excitation loop

Gain from PGA in State 1

0.025

Covered by DAC full-scale error measured

on an output of the excitation loop

RECONSTRUCTION FILTER (RCF)

3 dB Corner Frequency

50

kHz

1

There may be some system offsets and gain errors that can be calibrated at the system level to improve dc accuracy. Hence, the voltage swing at the output

of the DAC is ±800 mV to guarantee ±600 mV swing on the sensor.

SWITCH MATRIX SPECIFICATIONS

Table 4. Switch Matrix Specifications

Parameter

Min

Typ

Max

Unit

Test Conditions/Comments

RON1

Current Carrying Switches

Dx, DR1, Tx, and TR2

40

50

Ω

IVS

40

75

Ω

Noncurrent Carrying Switches

Px, Nx, and NR2

600

900

Ω

PR1

600

950

Ω

NL

260

350

Ω

PL

210

260

Ω

DC OFF LEAKAGE2

T and N Switches

370

pA

Sum value of four T switches and four N

switches

P Switches

340

pA

Sum value of four P switches

D Switches

350

pA

Sum value of four D switches