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PDF MAX1497 Data sheet ( Hoja de datos )
| Número de pieza | MAX1497 | |
| Descripción | 3.5- and 4.5-Digit / Single-Chip ADCs with LED Drivers and C Interface | |
| Fabricantes | Maxim Integrated | |
| Logotipo |  |
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19-3054; Rev 0; 11/03
3.5- and 4.5-Digit, Single-Chip ADCs with LED
Drivers and µC Interface
General Description
The MAX1497/MAX1499 low-power, 3.5- and 4.5-digit,
analog-to-digital converters (ADCs) with integrated light-
emitting diode (LED) drivers operate from a single 2.7V
to 5.25V power supply. They include an internal refer-
ence, a high-accuracy on-chip oscillator, and a multi-
plexed LED display driver. An internal charge pump
generates the negative supply needed to power the
integrated input buffers for single-supply operation. The
ADC is configurable for either a ±2V or ±200mV input
range and it outputs its conversion results to an LED
and/or to a microcontroller (µC). µC communication is
possible through an SPI™-/QSPI™-/MICROWIRE™-
compatible serial interface. The MAX1497 is a 3.5-digit
(±1999 count) device and the MAX1499 is a 4.5-digit
(±19,999 count) device.
The MAX1497/MAX1499 do not require external preci-
sion integrating capacitors, autozero capacitors, crystal
oscillators, charge pumps, or other circuitry required
with dual-slope ADCs (commonly used in panel meter
circuits).
These devices also feature on-chip buffers for the dif-
ferential signal and reference inputs, allowing direct
interface with high-impedance signal sources. In addi-
tion, they use continuous internal offset-calibration and
offer >100dB rejection of 50Hz and 60Hz line noise.
Other features include data hold and peak detection,
overrange and underrange detection, and a user-pro-
grammable low-battery monitor.
The MAX1499 is available in a 32-pin, 7mm ✕ 7mm
TQFP package and the MAX1497 is available in 28-pin
SSOP and 28-pin PDIP packages. All devices in this
family operate over the -40°C to +85°C extended tem-
perature range.
Digital Panel Meters
Hand-Held Meters
Digital Voltmeters
Digital Multimeters
Applications
Features
o High Resolution
MAX1499: 4.5 Digits (±19,999 Count)
MAX1497: 3.5 Digits (±1999 Count)
o Sigma-Delta ADC Architecture
No Integrating Capacitors Required
No Autozeroing Capacitors Required
>100dB of Simultaneous 50Hz and 60Hz
Rejection
o Operate from a Single 2.7V or 5.25V Supply
o Selectable Input Range of ±200mV or ±2V
o Selectable Voltage Reference: Internal 2.048V or
External
o Internal High-Accuracy Oscillator Needs No
External Components
o Automatic Offset Calibration
o Low Power (Exclude LED Driver Current)
Maximum 664µA Operating Current
Maximum 268mA Shutdown Current
o Small 32-Pin, 7mm x 7mm TQFP Package (4.5
Digits), 28-Pin SSOP Package (3.5 Digits)
o Also Available in a PDIP Package (3.5 Digits)
o Multiplexed LED Drivers
Resistor-Programmable Segment Current
o SPI-/QSPI-/MICROWIRE-Compatible Serial
Interface
o Extended Temperature Range (-40°C to +85°C)
Ordering Information
PART
TEMP RANGE
PIN-
PACKAGE
RESOLUTION
(DIGITS)
MAX1497EAI* -40°C to +85°C 28 SSOP
3.5
MAX1497EPI -40°C to +85°C 28 PDIP
3.5
MAX1499ECJ* -40°C to +85°C 32 TQFP
4.5
*Future product—contact factory for availability.
Pin Configurations appear at end of data sheet.
SPI/QSPI are trademarks of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corp.
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1 page  
3.5- and 4.5-Digit, Single-Chip ADCs with LED
Drivers and µC Interface
ELECTRICAL CHARACTERISTICS (continued)
(AVDD = DVDD = VDD = +2.7V to +5.25V, GND = 0, GLED = 0, VLED = +2.7V to +5.25V, VREF+ - VREF- = 2.048V (external reference)
CREF+ = CREF- = 0.1µF, CVNEG = 0.1µF. Internal clock mode, unless otherwise noted. All specifications are at TA = TMIN to TMAX.
Typical values are at TA = +25°C, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN TYP MAX UNITS
DVDD Current (Notes 8, 9)
IDVDD
DVDD = 5V
DVDD = 3.3V
Standby mode
320
180 µA
20
LED Drivers Bias Current
LED DRIVERS (Table 6)
From AVDD or VDD
120 µA
LED Supply Voltage
LED Shutdown Supply Current
VLED
ISHDN
LED driver shutdown mode
2.70
5.25 V
10 µA
LED Supply Current
ILED
Seven segments and decimal point on,
RISET = 25kΩ
176 mA
Display Scan Rate
fOSC
MAX1499
MAX1497
512
Hz
640
Segment Current Slew Rate
DIG_ Voltage Low
∆ISEG/∆t
VDIG IDIG_ = 176mA
25
0.178 0.190
mA/µs
V
Segment Drive Source Current
Matching
∆ISEG
±3 ±10
%
Segment Drive Source Current
Interdigit Blanking Time
ISEG VLED - VSEG = 0.6V, RISET = 25kΩ
18.0
21.5
4
25.5
mA
µs
_______________________________________________________________________________________ 5
5 Page 
3.5- and 4.5-Digit, Single-Chip ADCs with LED
Drivers and µC Interface
Pin Description (continued)
PIN
MAX1497 MAX1499
25 25
26 26
27 27
28 28
—6
—7
— 19
— 29
— 30
NAME
FUNCTION
VLED
SEGF
SEGG
SEGDP
AVDD
DVDD
DIG4
LED-Display Segment-Driver Supply. Connect to a +2.7V to +5.25V supply. Bypass with
a 0.1µF capacitor to GLED.
Segment F Driver
Segment G Driver
Segment DP Driver
Analog Positive Supply Voltage. Connect AVDD to a +2.7V to +5.25V power supply.
Bypass AVDD to GND with a 0.1µF capacitor.
Digital Positive Supply Voltage. Connect DVDD to a +2.7V to +5.25V power supply.
Bypass DVDD to GND with a 0.1µF capacitor.
Digit 4 Driver
LED_EN
Active-High LED Enable. The MAX1499 LED display driver turns off when LED_EN is
driven to logic low. The MAX1499 LED display driver turns on when LED_EN is driven to
logic high.
LOWBATT Low-Battery Voltage Monitor. When the LOWBATT input voltage is lower than 2.048V, the
LOWBATT bit in the status register is set to one.
Detailed Description
The MAX1497/MAX1499 low-power, highly integrated
ADCs with LED drivers convert a ±2V differential input
voltage (one count is equal to 100µV for the MAX1499
and 1mV for the MAX1497) with a sigma-delta ADC and
output the result to an LED or µC. An additional
±200mV input range (one count is equal to 10µV for the
MAX1499 and 100µV for the MAX1497) is available to
measure small signals with increased resolution.
The devices operate from a single 2.7V to 5.25V power
supply and offer 3.5-digit (MAX1497) or 4.5-digit
(MAX1499) conversion results. An internal 2.048V refer-
ence, internal charge pump, and a high-accuracy on-
chip oscillator eliminate external components.
The MAX1497/MAX1499 interface with a µC using an
SPI-/QSPI-/MICROWIRE-compatible serial interface.
Data can either be sent directly to the display or to the
µC first for processing before being displayed.
The devices also feature on-chip buffers for the differ-
ential input signal and external reference inputs, allow-
ing direct interface with high-impedance signal
sources. In addition, they use continuous internal offset-
calibration and offer >100dB of 50Hz and 60Hz line
noise rejection. Other features include data hold and
peak detection, overrange and underrange detection.
The MAX1499 also provides a low-battery monitor.
Analog Input Protection
Internal protection diodes limit the analog input range
from VNEG to (AVDD + 0.3V) for the MAX1499, and
from VNEG to (VDD to 0.3V) for the MAX1497. If the
analog input exceeds this range, limit the input current
to 10mA.
Internal Analog Input/Reference Buffers
The MAX1497/MAX1499 analog input/reference buffers
allow the use of high-impedance signal sources. The
input buffers’ common-mode input range allows the ana-
log inputs and the reference to range from -2.2V to +2.2V.
Modulator
The MAX1497/MAX1499 perform analog-to-digital con-
versions using a single-bit, 3rd-order, sigma-delta mod-
ulator. The sigma-delta modulator converts the input
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 MAX1497/MAX1499 modulator provides 3rd-order
frequency shaping of the quantization noise resulting
from the single-bit quantizer. The modulator is fully dif-
ferential for maximum signal-to-noise ratio and mini-
mum susceptibility to power-supply noise. A single-bit
data stream is then presented to the digital filter to
remove the frequency-shaped quantization noise.
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet MAX1497.PDF ] | |
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