FREQUENCY (kHz)
0–140
M A G N I T U D E (d B )
–120–100–800–40100
150250
–20–60–130–110–90–10–50–30–7050
2002308 G03
f SMPL = 500kHz SINAD = 73.6dB THD = –89.5dB
TYPICAL APPLICATION
FEATURES
APPLICATIONS
DESCRIPTION
8-Channel, 12-Bit ADC
The LTC ®2308 is a low noise, 500ksps, 8-channel, 12-bit
ADC with an SPI/MICROWIRE compatible serial interface. This ADC includes an internal reference and a fully differ-ential sample-and-hold circuit to reduce common-mode noise. The internal conversion clock allows the external serial output data clock (SCK) to operate at any frequency up to 40MHz.
The LTC2308 operates from a single 5V supply and draws just 3.5mA at a sample rate of 500ksps. The auto-shutdown feature reduces the supply current to 200μA at a sample rate of 1ksps.
The LTC2308 is packaged in a small 24-pin 4mm × 4mm QFN. The internal 2.5V reference and 8-channel multiplexer further reduce PCB board space requirements.
The low power consumption and small size make the LTC2308 ideal for battery operated and portable appli-cations, while the 4-wire SPI compatible serial interface makes this ADC a good match for isolated or remote data acquisition systems.
8192 Point FFT, f IN = 1kHz
■
12-Bit Resolution
■ 500ksps Sampling Rate ■ Low Noise: SINAD = 73.3dB ■ Guaranteed No Missing Codes ■ Single 5V Supply
■
Auto-Shutdown Scales Supply Current with Sample Rate
■ Low Power: 17.5mW at 500ksps 0.9mW Nap Mode 35μW Sleep Mode ■ nternal Reference ■ Internal 8-Channel Multiplexer ■ Internal Conversion Clock
■ SP /M CROW RE TM Compatible Serial Interface
■ Unipolar or Bipolar Input Ranges (Software Selectable)■
Separate Output Supply OV DD (2.7V to 5.25V)■ 24-Pin 4mm × 4mm QFN Package
■
High Speed Data Acquisition ■ Industrial Process Control ■ Motor Control ■ Accelerometer Measurements ■ Battery Operated Instruments
■ Isolated and/or Remote Data Acquisition
CH0-CH7
ANALOG INPUTS
0V TO 4.096V UNIPOLAR
p 2.048V BIPOLAR
PIN CONFIGURATION
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (AV DD , DV DD , OV DD ) ...........................6V Analog Input Voltage (Note 3) CH0 - CH7, COM, REF,
REFCOMP ....................(GND –0.3V) to (AV DD + 0.3V)Digital Input Voltage
(Note 3) ......................(GND –0.3V) to (DV DD + 0.3V)Digital Output Voltage .....(GND –0.3V) to (OV DD + 0.3V)Power Dissipation ...............................................500mW Operating Temperature Range
LTC2308C ................................................0°C to 70°C LTC2308I .............................................–40°C to 85°C Storage Temperature Range ...................–65°C to 150°C
(Notes 1, 2)
2425
2322212019
789TOP VIEW
UF PACKAGE
24-LEAD (4mm × 4mm) PLASTIC QFN
1011126
54321131415161718CH3CH4CH5CH6CH7COM GND SD0
SCK SDI CONVST AV DD
C H 2
C H 1
C H 0
D V D D
G N D
O V D D
V R E F
R E F C O M P
G N D
G N D
G N D
A V D D T JMAX = 150°C, θJA = 37°C/W
EXPOSED PAD (PIN 25) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
CONVERTER AND MULTIPLEXER CHARACTERISTICS
PARAMETER
CONDITIONS
MIN
TYP MAX UNITS Resolution (No Missing Codes)●12
Bits Integral Linearity Error (Note 6)●±0.3±1LSB Differential Linearity Error ●±0.25±1LSB Bipolar Zero Error (Note 7)●
±1±6LSB Bipolar Zero Error Drift 0.002LSB/°C Bipolar Zero Error Match ●±0.3±3LSB Unipolar Zero Error (Note 7)●
波纹板
±0.5±3LSB Unipolar Zero Error Drift 0.002LSB/°C Unipolar Zero Error Match
●
±0.3
±2
LSB
The ● denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at T A = 25°C. (Notes 4, 5)
LEAD FREE FINISH TAPE AND REEL PART MARKING*PACKAGE DESCRIPTION
TEMPERATURE RANGE LTC2308CUF#PBF LTC2308IUF#PBF
LTC2308CUF#TRPBF LTC2308IUF#TRPBF
23082308
24-Lead (4mm × 4mm) Plastic QFN 24-Lead (4mm × 4mm) Plastic QFN
0°C to 70°C –40°C to 85°C
Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi ed by a label on the shipping container.Consult LTC Marketing for information on non-standard lead based fi nish parts.For more information on lead free part marking, go to: www.linear/leadfree/ For more information on tape and reel specifi cations, go to: www.linear/tapeandreel/
PARAMETER CONDITIONS
MIN
TYP MAX UNITS Bipolar Full-Scale Error External Reference (Note 8)●
±1±9LSB Bipolar Full-Scale Error Drift External Reference
0.05LSB/°C Bipolar Full-Scale Error Match ●±0.5±3LSB Unipolar Full-Scale Error External Reference (Note 8)●
±1.5±8LSB Unipolar Full-Scale Error Drift External Reference
0.05LSB/°C Unipolar Full-Scale Error Match
●
±0.4
±3
LSB
CONVERTER AND MULTIPLEXER CHARACTERISTICS
The ● denotes the specifi cations
which apply over the full operating temperature range, otherwise specifi cations are at T A = 25°C. (Notes 4, 5)
ANALOG INPUT The ● denotes the specifi cations which apply over the full operating temperature range, otherwise
specifi cations are at T A = 25°C. (Note 4)
SYMBOL PARAMETER
CONDITIONS MIN TYP MAX UNITS
V IN +Absolute Input Range (CH0 to CH7)(Note 9)●–0.05AV DD V V IN –Absolute Input Range (CH0 to CH7,
COM)
Unipolar (Note 9)Bipolar (Note 9)
●●–0.05–0.05
AV DD /2AV DD
V V V IN + – V IN –Input Differential Voltage Range V IN = V IN + – V IN – (Unipolar)V IN = V IN + – V IN – (Bipolar)
●●0 to REFCOMP ±REFCOMP/2
V V
I IN Analog Input Leakage Current ●
±1
μA C IN Analog Input Capacitance
Sample Mode Hold Mode
555pF pF CMRR
Input Common Mode Rejection Ratio
70
dB
DYNAMIC ACCURACY The ● denotes the specifi cations which apply over the full operating temperature range,
otherwise specifi cations are at T A = 25°C and A IN = –1dBFS. (Notes 4, 10)
SYMBOL PARAMETER
TYP MAX UNITS SINAD Signal-to-(Noise + Distortion) Ratio f IN = 1kHz ●7173.3dB SNR Signal-to-Noise Ratio f IN = 1kHz
●71
73.4dB
THD Total Harmonic Distortion f IN = 1kHz, First 5 Harmonics ●–90–78dB SFDR
Spurious Free Dynamic Range f IN = 1kHz ●
–90–80
dB Channel-to-Channel Isolation f IN = 1kHz –109dB Full Linear Bandwidth (Note 11)
700kHz –3dB Input Linear Bandwidth 25MHz Aperture Delay 13ns Transient Reponse
Full-Scale Step 240
ns
INTERNAL REFERENCE CHARACTERISTICS
The
● denotes the specifi cations which apply over the
full operating temperature range, otherwise specifi cations are at T A = 25°C. (Note 4)
PARAMETER CONDITIONS MIN TYP MAX UNITS
V REF Output Voltage I OUT = 0● 2.47 2.50 2.53V
V REF Output Tempco I OUT = 0±25ppm/°C
V REF Output Impedance–0.1mA ≤ I OUT ≤ 0.1mA8kΩ
V REFCOMP Output Voltage I OUT = 0 4.096V
V REF Line Regulation AV DD = 4.75V to 5.25V0.8mV/V
DIGITAL INPUTS AND DIGITAL OUTPUTS
The
● denotes the specifi cations which apply over the
full operating temperature range, otherwise specifi cations are at T A = 25°C. (Note 4)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V IH High Level Input Voltage DV DD = 5.25V● 2.4V
V IL Low Level Input Voltage DV DD = 4.75V●0.8V
I IN High Level Input Current V IN = V DD●±10μA
C IN Digital Input Capacitance5pF
氟碳表面活性剂V OH High Level Output Voltage OV DD = 4.75V, I OUT = –10μA OV DD = 4.75V, I OUT = –200μA●44.74V
V
V OL Low Level Input Voltage OV DD = 4.75V, I OUT = 160μA
OV DD = 4.75V, I OUT = 1.6mA●0.05
0.4
V
V
I OZ Hi-Z Output Leakage V OUT = 0V to OV DD, CONVST High●±10μA C OZ Hi-Z Output Capacitance CONVST High15pF I SOURCE Output Source Current V OUT = 0V–10mA I SINK Output Sink Current V OUT = OV DD10mA
POWER REQUIREMENTS
The
● denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at T A = 25°C. (Note 4)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS AV DD Analog Supply Voltage 4.755 5.25V DV DD Digital Supply Voltage 4.755 5.25V OV DD Output Driver Supply Voltage 2.7 5.25V
I DD Supply Current
Nap Mode
Sleep Mode C L = 25pF
CONVST = 5V, Conversion Done
CONVST = 5V, Conversion Done
●
●
●
3.5
180
7
4.2
400
20
mA
μA
μA
P D Power Dissipation
Nap Mode
Sleep Mode 17.5
0.9
35
mW
mW
μW
Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime.
Note 2: All voltage values are with respect to ground with AV DD , DV DD and OV DD wired together (unless otherwise noted).
Note 3: When these pin voltages are taken below ground or above V DD , they will be clamped by internal diodes. These products can handle input currents greater than 100mA below ground or above V DD without latchup.Note 4: AV DD = 5V, DV DD = 5V, OV DD = 5V, f SMPL = 500kHz, internal reference unless otherwise specifi ed.
Note 5: Linearity, offset and full-scale specifi cations apply for a single-ended analog input with respect to COM.Note 6: Integral nonlinearity is defi ned as the deviation of a code from a straight line
passing through the actual endpoints of the transfer curve. The deviation is measured from the center of the quantization band.
TIMING CHARACTERISTICS The ● denotes the specifi cations which apply over the full operating temperature
range, otherwise specifi cations are at T A = 25°C. (Note 4)
SYMBOL PARAMETER
CONDITIONS
MIN TYP MAX UNITS f SMPL(MAX)Maximum Sampling Frequency ●500kHz f SCK Shift Clock Frequency ●书屋
杂志 40
MHz t WHCONV CONVST High Time (Note 9)●20ns t HD Hold Time SDI After SCK ↑● 2.5ns t SUDI Setup Time SDI Valid Before SCK ↑●
0ns t WHCLK SCK High Time f SCK = f SCK(MAX)●10ns t WLCLK SCK Low Time
f SCK = f SCK(MAX)●10ns t WLCONVST CONVST Low Time Durin
g Data Transfer (Note 9)●410ns t HCONVST Hold Time CONVST Low After Last SCK ↓(Note 9)
●20
ns
t CONV Conversion Time ● 1.3
1.6
μs t ACQ Acquisition Time
7th SCK ↑ to CONVST ↑ (Note 9)●
240
ns t REFWAKE REFCOMP Wakeup Time (Note 12)C REFCOMP = 10μF, C REF = 2.2μF 200ms t dDO SDO Data Valid After SCK ↓C L = 25pF (Note 9)●10.8
12.5ns t hDO SDO Hold Time After SCK ↓C L = 25pF ●4
ns t en SDO Valid After CONVST ↓C L = 25pF ●1115ns t dis Bus Relinquish Time C L = 25pF ●
1115ns t r SDO Rise Time C L = 25pF 4ns t f SDO Fall Time C L = 25pF
4ns t CYC
Total Cycle Time
2
μs琦君作者简介
Note 7: Bipolar zero error is the offset voltage measured from –0.5LSB when the output code fl ickers between 0000 0000 0000 and 1111 1111 1111. Unipolar zero error is the offset voltage measured from +0.5LSB when the output code fl ickers between 0000 0000 0000 and 0000 0000 0001.
Note 8: Full-scale bipolar error is the worst-case of –FS or +FS untrimmed deviation from ideal fi rst and last code transitions and includes the effect of offset error. Unipolar full-scale error is the deviation of the last code transition from ideal and includes the effect of offset error. Note 9: Guarant
eed by design, not subject to test.Note 10: All specifi cations in dB are referred to a full-scale ±2.048V input with a 2.5V reference voltage.
Note 11: Full linear bandwidth is defi ned as the full-scale input frequency at which the SINAD degrades to 60dB or 10 bits of accuracy.
Note 12: REFCOMP wakeup time is the time required for the REFCOMP pin to settle within 0.5LSB at 12-bit resolution of its fi nal value after waking up from SLEEP mode.
FREQUENCY (kHz)
–120C R O S S T A L K (d B )
–100–90
–70–600.1
10100
1000
3208 G04
–140
1
–80–110
–130FREQUENCY (kHz)
1
50
S N R (d B )
707580101001000
3208 G05
6560
55FREQUENCY (kHz)
1
50
S I N A D (d B )
707580101001000
3208 G06
656055FREQUENCY (kHz)
1
–80T H D (d B )
–70–60101001000
3208 G07
–90–85–75–65
–95
–100
SAMPLING FREQUENCY (ksps)
1
2.0S U P P L Y C U R R E N T (m A )
2.5
3.03.510100
1000
3208 G08
1.51.00.5
OUTPUT CODE
D N L (L S B )
00.250.504096
2308 G02
–0.25–0.50–1.00
1024
2048
3072
–0.75
1.000.75FREQUENCY (kHz)
0–140
M A G N I T U D E (d B )
–120–100–800–40100
150250
–20–60–130–110–90–10–50–30–7050
2002308 G03
SNR = 73.7dB SINAD = 73.6dB
THD = –89.5dB
OUTPUT CODE
I N L (L S B )
00.250.504096
2308 G01
–0.25–0.50–1.00
1024
2048
3072
–0.751.000.75TYPICAL PERFORMANCE CHARACTERISTICS
Integral Nonlinearity vs Output Code
Differential Nonlinearity vs Output Code
1kHz Sine Wave 8192 Point FFt Plot
Crosstalk vs Frequency for an Adjacent Pair
SNR vs Input Frequency
SINAD vs Input Frequency
THD vs Input Frequency
Supply Current vs Sampling Frequency
Supply Current vs Temperature
TEMPERATURE (o C)
–50
–25
0S U P P L Y C U R R E N T (m A )
2
05075
3208 G09
1
4
3
25100
125
T A = 25°C, AV DD = DV DD = OV DD = 5V,
f SMPL = 500ksps, Internal Reference, unless otherwise noted.
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