MAX1365ECM+ Maxim Integrated Products, MAX1365ECM+ Datasheet - Page 12

• Manufacturer Part Number: MAX1365ECM+
• Description: IC PANEL METER 4.5 DIG 48LQFP
• Manufacturer: Maxim Integrated Products

Specifications of MAX1365ECM+

• Display Type: LED
• Configuration: 7 Segment
• Digits Or Characters: A/D 4.5 Digits
• Voltage - Supply: 2.7 V ~ 5.25 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 48-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Supply: -
• Interface: -

Stand-Alone, 4.5-/3.5-Digit Panel Meters
with 4–20mA Output
signal into a digital pulse train whose average duty
cycle represents the digitized signal information. The
modulator quantizes the input signal at a much higher
sample rate than the bandwidth of the input. The
MAX1365/MAX1367 modulator provides 3rd-order fre-
quency shaping of the quantization noise resulting from
the single-bit quantizer. The modulator is fully differen-
tial for maximum signal-to-noise ratio and minimum sus-
ceptibility to power-supply noise. A single-bit data
stream is then presented to the digital filter to remove
the frequency-shaped quantization noise.
The MAX1365/MAX1367 contain an on-chip digital low-
pass filter that processes the data stream from the
modulator using a SINC
The SINC
periods (4 x 200ms). The MAX1365/MAX1367 have
25% overrange capability built into the modulator and
digital filter. The digital filter is optimized for the f
equal to 4.9152MHz. The frequency response of the
SINC
where N is the oversampling ratio, and f
data rate = 5Hz.
Figure 1 shows the filter frequency response. The
SINC
times the first notch frequency (5Hz). The oversampling
ratio (OSR) for the MAX1367 is 128 and the OSR for the
MAX1365 is 1024. The output data rate for the digital fil-
ter corresponds to the positioning of the first notch of
the filter’s frequency response. The notches of the
SINC
frequency. The SINC
better than 100dB at these notches. For example, 50Hz
is equal to 10 times the first notch frequency and 60Hz
is equal to 12 times the first notch frequency. For large
12
______________________________________________________________________________________
4
4
4
filter is calculated as follows:
filter are repeated at multiples of the first notch
characteristic -3dB cutoff frequency is 0.228
4
filter has a settling time of four output data
H z
H f
( )
( )
=
=
4
N
1







1 1
N
filter provides an attenuation of
4







sin( ) x
(
sin
(
response:
1
−
x
sin
−
Z



Z
N
−
−






N
1
π
4
f
π
)
m
)
f
f




m
f



4
Filter Characteristics



Digital Filtering







4
m
= N x output
CLK
step changes at the input, allow a settling time of
800ms before valid data is read.
The MAX1365/MAX1367 contain an internal oscillator.
Using the internal oscillator saves board space by
removing the need for an external clock source. The
oscillator is optimized to give 50Hz and 60Hz power-
supply and common-mode rejection.
The MAX1365/MAX1367 contain an internal charge pump
to provide the negative supply voltage for the internal
analog input/reference buffers. The bipolar input range of
the analog input/reference buffers allows this device to
accept negative inputs with high source impedances.
Connect a 0.1µF capacitor from NEGV to GND.
The MAX1365 has a 4.5-digit common-cathode display
driver, and the MAX1367 has a 3.5-digit common-cath-
ode display driver. In addition, the LED drivers of the
MAX1365/MAX1367 feature peak-detection and data-
hold circuitry.
Figures 2 and 3 show the connection schemes for a
standard seven-segment LED display. The LED update
rate is 2.5Hz. Figure 4 shows a typical common-cath-
ode configuration for two digits. In common-cathode
configuration, the cathodes of all LEDs in a digit are
connected together. Each segment driver of the
MAX1365/MAX1367 connects to its corresponding
LED’s anodes. For example, segment driver SEGA con-
nects to all LED segments designated as A. Similar
configurations are used for other segment drivers.
Figure 1. Frequency Response of the SINC
-120
-160
-200
-40
-80
0
0
10
20
FREQUENCY (Hz)
30
LED Driver (Table 1)
40
4
Internal Clock
Filter (Notch at 60Hz)
50
Charge Pump
60