TMC1175AR3C20 View Datasheet(PDF) - Cadeka Microcircuits LLC.
Part Name
Description
Manufacturer
TMC1175AR3C20 Datasheet PDF : 18 Pages
| |||
PRODUCT SPECIFICATION
TMC1175A
Pin Descriptions
Pin Number
Pin Name
M7
R3 Pin Type Pin Function Description
Inputs
VIN
19
23 RT – RB Analog Input. The input voltage conversion range lies between the
voltages applied to the RT and RB pins.
RT
17
20
2.6V Reference Voltage Top Input. RT is the top input to the reference
resistor ladder. A DC voltage applied to RT defines the positive end
of the VIN conversion range.
RB
23
27
0.6V Reference Voltage Bottom Input. RB is the bottom input to the
reference resistor ladder. A DC voltage applied to RB defines the
negative end of the VIN conversion range.
VR+
16
19
Reference Voltage Top Source. VR+ is the internal pull-up
reference resistor for self-bias operations.
VR–
22
26
Reference Voltage Bottom Source. VR- is the internal pull-down
reference resistor for self-bias operations.
OE
1
2
CMOS Output Enable. (CMOS-compatible) When LOW, D7-0 are enabled.
When HIGH, D7-0 are in a high-impedance state.
CONV
12
14 CMOS Convert (Clock) Input. (CMOS-compatible) VIN is sampled on the
falling edge of CONV.
Outputs
D7-0
10–3
12–9, CMOS/ Data Outputs (D7 = MSB). Eight-bit CMOS- and TTL-compatible
7–4
TTL digital outputs. Data is output following the rising edge of CONV.
Power
VDDA
14, 15, 18 17, 18, +5V Analog Supply Voltage. Independent +5 volt power connection to
21
analog comparator circuits.
VDDD
11, 13
13, 16
+5V Digital Supply Voltage. Independent +5 volt power connection to
digital error correction and output drivers.
AGND
20, 21 24, 25 0.0V Analog Ground. Connect to the system analog ground plane.
DGND
2, 24 3, 28 0.0V Digital Ground. Connect to the system analog ground plane.
No Connect
N/C
1, 8, 15, open Not Connected.
22
Bandwidth Specification Notes
The specification for bandwidth of an A/D converter is some-
what different from the normal frequency-response specifi-
cation used in amplifiers and filters. An understanding of the
differences will help in selecting converters properly for par-
ticular applications.
A/D conversion comprises two distinct processes: sampling
and quantizing. Sampling is “grabbing” a snapshot of the
input signal and holding it steady for quantizing. The quan-
tizing process is approximating the analog input, which may
be any value within the conversion range, with its nearest
numerical value. While sampling is a high-frequency pro-
cess, quantizing operates on a dc signal, held steady by the
track/hold circuit. Therefore, the sampling process is what
relates to the dynamic characteristics of the converter.
Sampling involves an aperture time, the time during which
the track/hold is trying to capture the input signal and settle
on a dc value to hold. It is analogous to the shutter speed of a
camera: the shorter the aperture (or faster the shutter) the less
the signal will be blurred, and the less uncertainty there will
be in the quantized value.
For example, a 10 MHz sinewave with a 1V peak amplitude
(2Vp-p) has a maximum slew rate of 2πfA at zero crossing,
or 62.8V/µs. With an 8-bit A/D converter, q (the quantization
step size) = 2V/255 = 7.8mV. The input signal will slew one
LSB in 124ps. To limit the error (and noise) contribution due
to aperture effects to 1/2LSB, the aperture must be shorter
than 62ps.
REV. 1.3.3 2/28/02
5
Share Link: 