LTC1402IGN Linear Technology, LTC1402IGN Datasheet - Page 18

• Manufacturer Part Number: LTC1402IGN
• Description: IC ADC 12BIT 2.2MSPS SHDN 16SSOP
• Manufacturer: Linear Technology

Specifications of LTC1402IGN

• Number Of Bits: 12
• Sampling Rate (per Second): 2.2M
• Data Interface: MICROWIRE™, Serial, SPI™
• Number Of Converters: 1
• Power Dissipation (max): 150mW
• Voltage Supply Source: Analog and Digital, Dual ±
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-SSOP (0.150", 3.90mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

LTC1402
APPLICATIONS
HARDWARE INTERFACE TO TMS320C54x
The LTC1402 is a serial output ADC whose interface has
been designed for high speed buffered serial ports in fast
digital signal processors (DSPs). Figure 14 shows an
example of this interface using a TMS320C54X.
The buffered serial port in the TMS320C54x has direct
access to a 2kB segment of memory. The ADC’s serial data
can be collected in two alternating 1kB segments, in real
time, at the full 2.2Msps conversion rate of the LTC1402.
The DSP assembly code sets frame sync mode at the BFSR
pin to accept an external positive going pulse, and the
serial clock at the BCLKR pin to accept an external positive
18
U
LTC1402
INFORMATION
U
OGND
CONV
OV
D
SCK
OUT
DD
11
16
15
10
9
W
Figure 14. DSP Serial Interface to TMS320C54x
CONV
CLK
U
INTERFACELINK
3-WIRE SERIAL
edge clock. Buffers near the LTC1402 may be added to
drive long tracks to the DSP to prevent corruption of the
signal to LTC1402. This configuration is adequate to
traverse a typical system board, but source resistors at the
buffer outputs, and termination resistors at the DSP may
be needed to match the characteristic impedance of very
long transmission lines. If you need to terminate the D
transmission line, buffer it first with one or two 74ACxx
gates. The TTL threshold inputs of the DSP port respond
properly to the 2.5V swing of the terminated transmission
lines. The OV
driven directly from the DSP.
5V
REF
DD
B11
supply output driver supply voltage can be
B10
V
BFSR
BCLKR
BDR
TMS320C54x
CC
1402 F14
OUT