isppac20 Lattice Semiconductor Corp., isppac20 Datasheet - Page 20

• Manufacturer Part Number: isppac20
• Description: In-system Programmable Analog Circuit
• Manufacturer: Lattice Semiconductor Corp.

Figure 12. ispPAC20 DAC Interface Options
Table 3. DAC Address Modes
Notes: (1) DAC output goes from –FS to +FS during E
commands) before settling to the final input code value.
Theory of Operation (Continued)
DAC Input Comes From:
DAC Updated On:
Rising Edge CS Updates:
DAC Output at Power-Up:
TDO Serial Output in
Hi-Z State During JTAG
AddDAC Operation
E
2
Cells Programmed Via:
Action
*Decoded from the user selection in the DAC port configuration pop-up.
CS(5)
TCK
TDI
CS
Registers updated after JTAG command(s):
(1) DBE, PrgDAC (DMode=1)
(2) AddDAC, DBE, PrgDAC (DMode=0)
(3) VerDAC
(4) AddDAC (E
(5) Rising edge of CS (only if DMode=1)
DAC Parallel Input Data Pins D0-D7
SPI mode only: Rising edge of CS
Otherwise active during
Shift-DR/IR JTAG state
(pre-set to 80h at power-up)
(pre-set to 80h at power-up)
Parallel Input Data Latches
JTAG/E
E
Serial Input Data Latches
If E 2 bit DisTDO =1,
During Update-DR,
falling edge TCK (1)
2
Serial DAC Input Shift
CMOS Memory
Serial Input SR
Stored E
E
Serial Latch
2
(4)
(2)
Register (SR)
DAC Address
CMOS Memory
2
2
Serial Mode
bit DSthru=1, ENSPI=0)
2
(1)
Value
2
(3)
programming cycle (JTAG DBE or DAC Bulk Erase, and PrgDAC or Program DAC
JTAG/Direct & SPI
Parallel
80h (Vout+, Vout-=2.5V) 80h (Vout+, Vout-=2.5V) 80h (Vout+, Vout-=2.5V)
No TDO if TCK pin
Parallel Latches
Parallel Latches
Rising Edge CS
Parallel Mode
JTAG/E
Parallel Latch
is not clocked
Serial Latch
20
2
JTAG/Direct
JTAG/E
Address
Parallel
Mode
SPI
Specifications ispPAC20
JTAG/Direct Serial Mode
2
Otherwise active during
Shift-DR/IR JTAG state
If E
During Update-DR,
falling edge TCK
Serial Input SR
ENSPI
2
TDO
Serial Latch
Serial Latch
Pin
bit DisTDO =1,
0
0
0
1
DSthru
ENSPI Input Pin
DSthru E
DMode Input Pin
E
Inputs
2
DAC
X
0
0
1
Bit
DMode
2
Pin
X
X
0
1
Bit*
SPI Serial Mode
When CS is high
Rising Edge CS
No E
Serial Latch
Serial Latch
2
Access