MAX149AEAP Maxim Integrated Products, MAX149AEAP Datasheet - Page 21
MAX149AEAP
Manufacturer Part Number
MAX149AEAP
Description
ADC (A/D Converters) Integrated Circuits (ICs)
Manufacturer
Maxim Integrated Products
Datasheet
1.MAX148BCAP.pdf
(23 pages)
Specifications of MAX149AEAP
Architecture
SAR
Conversion Rate
133 KSPs
Input Type
Voltage
Maximum Power Dissipation
640 mW
Maximum Operating Temperature
+ 85 C
Mounting Style
SMD/SMT
Package / Case
SSOP-20
Minimum Operating Temperature
- 40 C
Lead Free Status / Rohs Status
No
The MAX148/MAX149 can interface with QSPI using the
circuit in Figure 20 (f
0). This QSPI circuit can be programmed to do a conver-
sion on each of the eight channels. The result is stored
in memory without taxing the CPU, since QSPI incorpo-
rates its own microsequencer.
The MAX148/MAX149 are QSPI compatible up to the
maximum external clock frequency of 2MHz.
Figure 21 shows an application circuit to interface the
MAX148/MAX149 to the TMS320 in external clock mode.
The timing diagram for this interface circuit is shown in
Figure 22.
Use the following steps to initiate a conversion in the
MAX148/MAX149 and to read the results:
Figure 22. TMS320 Serial-Interface Timing Diagram
1) The TMS320 should be configured with CLKX (trans-
High-Speed Digital Interfacing with QSPI
mit clock) as an active-high output clock and CLKR
(TMS320 receive clock) as an active-high input
clock. CLKX and CLKR on the TMS320 are tied
together with the MAX148/MAX149’s SCLK input.
SSTRB
DOUT
SCLK
DIN
CS
______________________________________________________________________________________
START
+2.7V to +5.25V, Low-Power, 8-Channel,
SCLK
SEL2
= 2.0MHz, CPOL = 0, CPHA =
TMS320LC3x Interface
SEL1
SEL0
UNI/BIP
SGL/DIF
PD1
2) The MAX148/MAX149’s CS pin is driven low by the
3) An 8-bit word (1XXXXX11) should be written to the
4) The MAX148/MAX149’s SSTRB output is monitored
5) The TMS320 reads in one data bit on each of the
6) Pull CS high to disable the MAX148/MAX149 until
PD0
TMS320’s XF_ I/O port to enable data to be clocked
into the MAX148/MAX149’s DIN.
MAX148/MAX149 to initiate a conversion and place
the device into external clock mode. See Table 1 to
select the proper XXXXX bit values for your specific
application.
through the TMS320’s FSR input. A falling edge on
the SSTRB output indicates that the conversion is in
progress and data is ready to be received from the
MAX148/MAX149.
next 16 rising edges of SCLK. These data bits rep-
resent the 10 + 2-bit conversion result followed by 4
trailing bits, which should be ignored.
the next conversion is initiated.
Serial 10-Bit ADCs
MSB
B8
S1
S0
HIGH
IMPEDANCE
HIGH
IMPEDANCE
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