Rainbow Electronics MAXQ3120 - Manual (Page 30)

+Denotes a Pb-free/RoHS-compliant device.
MAXQ3120
Filter Results
Below is the summary of the SNR and THD values
before and after applying the above LPFs, for 60
MAXQ3120 units.
An application engineer can easily implement his own
favorite lowpass filters to optimize MAXQ3120 for his
target applications. However, he does need to consider
the filter complexity and its processor resource require-
ment (CPU cycles and storage space) to strike an opti-
mal balance. The above 23-tap LPF takes 23 x 2 bytes
of RAM and 107 clock cycles of the MAXQ3120 to com-
plete. Note that the number of cycles varies from filter
to filter because the number of shifts required to nor-
malize the multiply-accumulate result will vary.
High-Precision ADC
Mixed-Signal Microcontroller
30 ____________________________________________________________________
SNR THD
CONDITION
MIN AVG MAX MIN AVG MAX
Before LPF 56.5 56.8 57.1 -84.5 -81.1 -77.3
After LPF, 21st Harmonic 68.2 70.7 71.4 -85.8 -83.1 -79.4
After LPF, 7th Harmonic 71.5 73.8 74.7 -88.9 -85.7 -82.0
Selector Guide
PART TEMP RANGE
PROGRAM
MEMORY
DATA
MEMORY
LCD
SEGMENTS
EXTERNAL
INTERRUPTS
USARTS
PIN-
PACKAGE
MAXQ3120-FFN -40°C to +85°C 16kWord Flash 256 Word SRAM 112 3 2 80 MQFP
MAXQ3120-FFN+ -40°C to +85°C 16kWord Flash 256 Word SRAM 112 3 2 80 MQFP