xr16m752im48 Exar Corporation, xr16m752im48 Datasheet - Page 12

• Manufacturer Part Number: xr16m752im48
• Description: Xr68m752 -high Performance Duart With 64-byte Fifo
• Manufacturer: Exar Corporation

XR16M752/XR68M752
HIGH PERFORMANCE DUART WITH 64-BYTE FIFO
When using 4X sampling mode, the bit time will have a jitter of
multiple of 4.
with the following equation(s):
The closest divisor that is obtainable in the M752 can be calculated using the following formula:
In the formulas above, please note that:
TRUNC (N) = Integer Part of N. For example, TRUNC (5.6) = 5.
ROUND (N) = N rounded towards the closest integer. For example, ROUND (7.3) = 7 and ROUND (9.9) = 10.
A >> B indicates right shifting the value ’A’ by ’B’ number of bits. For example, 0x78A3 >> 8 = 0x0078.
F
IGURE
ROUND( (Required Divisor - TRUNC(Required Divisor) )*16)/16 + TRUNC(Required Divisor), where
Required Divisor (decimal)=(XTAL1 clock frequency / prescaler) /(serial data rate x 16), with 16X mode, DLD[5:4]=’00’
Required Divisor (decimal)= (XTAL1 clock frequency / prescaler / (serial data rate x 8), with 8X mode, DLD[5:4] = ’01’
Required Divisor (decimal)= (XTAL1 clock frequency / prescaler / (serial data rate x 4), with 4X mode, DLD[5:4] = ’10’
5. B
When using a non-standard data rate crystal or external clock, the divisor value can be calculated
AUD
XTAL2
XTAL1
R
ATE
G
DLD = ROUND( (Required Divisor-TRUNC(Required Divisor) )*16)
ENERATOR
Crystal
Buffer
Osc/
DLL = TRUNC(Required Divisor) & 0xFF
To Other
DLM = TRUNC(Required Divisor) >> 8
Channel
Divide by 4
Divide by 1
Prescaler
Prescaler
12
MCR Bit-7=0
MCR Bit-7=1
(default)
DLL, DLM and DLD
Fractional Baud
Rate Generator
± 1/8 whenever DLD is non-zero, odd and not a
Registers
Logic
16X or 8X or 4X
and Receiver
to Transmitter
Rate Clock
Sampling
REV. 1.0.2