TEXAS INSTRUMENTS THS14F01, THS14F03 Technical data

查询THS14F01供应商
14-BIT, 1 MSPS/ 3 MSPS, DSP COMPATIBLE, ANALOG-TO-DIGITAL CONVERTERS
THS14F01, THS14F03
WITH FIFO INTERNAL REFERENCE AND PGA
SLAS285 – JUNE 2000
features
14-Bit Resolution
1 MSPS and 3 MSPS Speed Grades Available
On-Chip FIFO For Optimized Data Transfer
Differential Nonlinearity (DNL) ±0.6 LSB Typ
Integral Nonlinearity (INL) ±1.5 LSB Typ
Internal Reference
Differential Inputs
Programmable Gain Amplifier
µP Compatible Parallel Interface
Timing Compatible With TI 6000 DSP Family
3.3-V Single Supply
Power-Down Mode
Monolithic CMOS Design
PFB PACKAGE
DD
IN+AVAGND
AGND
applications
(TOP VIEW)
DD
DD
AV
AGND
DV
xDSL Front Ends Communication Industrial Control Instrumentation Automotive
A0A1FOVL
INT
CS
47 46 45 44 4348 42
IN–
1
AV
VBG
CML REF+ REF–
AGND AGND DGND
NC – No internal connection
DD
OV D13 D12
2 3 4 5 6 7 8 9 10 11 12
13
14 15
D11
DD
DV
16
DGND
17 18 19 20
D9D8D7
D10
40 39 3841
21
DD
DV
22 23 24
D5D4D3
D6
37
36 35 34 33 32 31 30 29 28 27 26 25
WR OE DGND DGND CLK DV
DD
DV
DD
D0 D1 D2 DV
DD
DGND
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters.
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Copyright 2000, Texas Instruments Incorporated
1
THS14F01, THS14F03 14-BIT, 1 MSPS/ 3 MSPS, DSP COMPATIBLE, ANALOG-TO-DIGITAL CONVERTERS WITH FIFO INTERNAL REFERENCE AND PGA
SLAS285 – JUNE 2000
description
The THS14F01 and THS14F03 are 14-bit, 1 MSPS/ 3 MSPS, single supply analog-to-digital converters with a FIFO, internal reference, differential inputs, programmable input gain, and an on-chip sample and hold amplifier.
Implemented with a CMOS process, the device has outstanding price/performance and power/speed ratios. The THS14F01 and THS14F03 are designed for use with 3.3-V systems, and with a high-speed µP compatible parallel interface, making them the first choice for solutions based on high-performance DSPs like the TI TMS320C6000 series.
The THS14F01 and THS14F03 are available in a TQFP-48 package in standard commercial and industrial temperature ranges.
functional block diagram
VBG
IN+
IN–
CLK
1.5 V BG
PGA
0..7 dB
REF+
REF
14-Bit
ADC
6
CONTROL
LOGIC
AVAILABLE OPTIONS
T
A
0°C to 70°C
–40°C to 85°C
14 15
PACKAGED DEVICE
TQFP (PFB)
THS14F01CPFB, THS14F03CPFB
THS14F01IPFB, THS14F03IPFB
32-Word
FIFO+
Buffer
REF–
D[13:0] + OV bit
A[1:0]
CS WR OE INT FOVL
2
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I/O
DESCRIPTION
THS14F01, THS14F03
14-BIT, 1 MSPS/ 3 MSPS, DSP COMPATIBLE, ANALOG-TO-DIGITAL CONVERTERS
WITH FIFO INTERNAL REFERENCE AND PGA
Terminal Functions
TERMINAL
NAME NO.
A[1:0] 40, 41 I Address input AGND 7,8, 44,
AV
DD
CLK 32 I Clock input CML 4 Reference midpoint. This pin requires a 0.1-µF capacitor to AGND. CS 37 I Chip select input. Active low DGND 9, 15, 25,
DV
DD
D[13:0] 11, 12, 13,
FOVL 39 O FIFO Overflow. Asserted when FIFO is full. Programmable polarity IN+ 48 I Positive differential analog input IN– 1 I Negative differential analog input INT 38 O Interrupt output. Asserted when FIFO trigger level is reached. Programmable polarity OE 35 I Output enable. Active low OV 10 O Out of range output REF+ 5 O Positive reference output. This pin requires a 0.1-µF capacitor to AGND. REF– 6 O Negative reference output. This pin requires a 0.1-µF capacitor to AGND. VBG 3 I Reference input. This pin requires a 1-µF capacitor to AGND. WR 36 I Write signal. Active low
45, 46
2, 43, 47 P Analog power supply
33, 34
14, 20, 26,
30, 31, 42
16, 17, 18, 19, 21, 22, 23, 24, 27,
28, 29
P Analog ground
P Digital ground
P Digital power supply
I/O Data inputs/outputs
SLAS285 – JUNE 2000
absolute maximum ratings over operating free-air temperature (unless otherwise noted)
Supply voltage, (AVDD to AGND) 4V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Supply voltage, (DVDD to DGND) 4V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reference input voltage range, VBG – 0.3 V to AV
DD
+ 0.3 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Analog input voltage range – 0.3 V to AVDD + 0.3 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Digital input voltage range – 0.3 V to DV Operating free-air temperature range, T
: C suffix 0°C to 70°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A
DD
+ 0.3 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
I suffix –40°C to 85°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage temperature range, T
stg
–65°C to 150°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lead temperature 1.6 mm (1/16 inch) from case for 10 seconds 260°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
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3
THS14F01, THS14F03
Clock frequenc
f
Operating free-air temperature
°C
INL
Integral nonlinearit
Best fit
LSB
THD
Total harmonic distortion
dB
SNR
Signal-to-noise ratio
dB
SINAD
Signal-to-noise ratio
distortion
dB
SFDR
Spurious free dynamic range
dB
14-BIT, 1 MSPS/ 3 MSPS, DSP COMPATIBLE, ANALOG-TO-DIGITAL CONVERTERS WITH FIFO INTERNAL REFERENCE AND PGA
SLAS285 – JUNE 2000
recommended operating conditions
MIN NOM MAX UNIT
Supply voltage, AVDD, DV High level digital input, V Low level digital input, V Load capacitance, C
y,
Clock duty cycle 40% 50% 60%
p
CLK
DD
IH
IL
L
THS14F01 0.1 1 1 MHz THS14F03 0.1 3 3 MHz
p
C suffix 0 25 70 I suffix –40 25 85
electrical characteristics over recommended operating conditions
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
Power Supply
I
DDA
I
DDD
DC Characteristics
DNL Differential nonlinearity ±0.6 ±1 LSB
AC Characteristics
ENOB Effective number of bits 11.2 1 1.5 Bits
FIFO trigger level = 10 samples. Performance is ensured with the output enable signal (OE on CLK.
Analog supply current 81 90 mA Digital supply current 5 10 mA Power 270 360 mW Power down current 20 µA
Resolution 14 Bits
y
Offset error IN+ = IN–, PGA = 0 dB 0.3 %FSR Gain error PGA = 0 dB 1 %FSR
+
p
Analog input bandwidth 140 MHz
THS14F01 THS14F03
THS14F01/3 fi = 100 kHz –81 THS14F03 fi = 1 MHz –78 THS14F01/3 fi = 100 kHz 72 THS14F03 fi = 1 MHz 70 72 THS14F01/3 fi = 100 kHz 70 THS14F03 fi = 1 MHz 69 70 THS14F01/3 fi = 100 kHz 80 THS14F03 fi = 1 MHz 73 80
) being low during no more than one rising clock edge
3 3.3 3.6 V 2 3.3 V
0 0.8 V 5 15 pF
±1.5 ±2.5 ±1.5 ±2.5
°
4
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VBG
f
Clock frequenc
14-BIT, 1 MSPS/ 3 MSPS, DSP COMPATIBLE, ANALOG-TO-DIGITAL CONVERTERS
electrical characteristics (continued)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
Reference Voltage
Bandgap voltage, internal mode 1.425 1.5 1.575 V Input impedance 40 k Positive reference voltage, REF+ 2.5 V Negative reference voltage, REF– 0.5 V Reference difference, REF, REF+ – REF– 2 V Accuracy, internal reference 5% Temperature coefficient 40 ppm/°C Voltage coefficient 200 ppm/V
Analog Inputs
Positive analog input, IN+ 0 AV Negative analog input, IN– 0 AV Analog input voltage difference Ain = IN+ – IN–, V Input impedance 25 k PGA range 0 7 dB PGA step size 1 dB PGA gain error ±0.25 dB
Digital Inputs
V
IH
V
IL
Digital Outputs
V
OH
V
OL
I
OZ
Clock Timing (CS low)
CLK
t
d
High-level digital input 2 V Low-level digital input 0.8 V Input capacitance 5 pF Input current ±1 µA
High-level digital output IOH = 50 µA 2.6 V Low-level digital output IOL = 50 µA 0.4 V Output current, high impedance ±10 µA
y
Output delay time 25 ns Latency 9.5 Cycles
THS14F01, THS14F03
WITH FIFO INTERNAL REFERENCE AND PGA
SLAS285 – JUNE 2000
ref
V V V
DD DD
= REF+ – REF– –V
ref
THS14F01 0.1 1 1 MHz THS14F03
ref
0.1 3 3 MHz
V
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THS14F01, THS14F03 14-BIT, 1 MSPS/ 3 MSPS, DSP COMPATIBLE, ANALOG-TO-DIGITAL CONVERTERS WITH FIFO INTERNAL REFERENCE AND PGA
SLAS285 – JUNE 2000
PARAMETER MEASUREMENT INFORMATION
sample timing
The THS14F01/3 core is based on a pipeline architecture with a latency of 9.5 samples. The conversion results are stored in the FIFO 9.5 clock cycles after the input signal was sampled.
Analog
Input
S9
S11
S10
S12
CLK
INT
Data
to FIFO
t
w(CLK)
t
t
w(CLK)
d
C1 C2
C3
Figure 1. Sample Timing
INT goes active if the programmed FIFO level is reached. INT is either low or high active depending on the polarity bit (IP) within the control word. This signal is set synchronously to the CLK signal. It is reset by a read access to the FIFO once the number of samples in the FIFO is below the programmed threshold level.
6
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THS14F01, THS14F03
14-BIT, 1 MSPS/ 3 MSPS, DSP COMPATIBLE, ANALOG-TO-DIGITAL CONVERTERS
WITH FIFO INTERNAL REFERENCE AND PGA
SLAS285 – JUNE 2000
PARAMETER MEASUREMENT INFORMATION
The parallel interface of the THS14F01/3 ADC features 3-state buffers making it possible to directly connect it to a data bus. The output buffers are enabled by driving the OE input low.
Besides the sample results, it is also possible to read back the values of the control register, the PGA register, and the control register. Which register is read is determined by the address inputs A[1,0]. The ADC results are available at address 0.
The timing of the control signals is described in the following sections. The FIFO can be disabled by setting FC to 0 (FIFO reset, default at power on). This makes it possible to access
the device synchronously. In this case the data is updated on every clock cycle.
Analog
Input
S9
S11
S10
S12
CLK
D[13:0]
OV
OE
A[1:0]
CS
t
w(CLK)
C0
t
en
X X
t
su(OE-ACS)
t
w(CLK)
t
d
C1 C2
C3
Figure 2. Sample Timing
t
dis
t
h(A)
t
h(CS)
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THS14F01, THS14F03 14-BIT, 1 MSPS/ 3 MSPS, DSP COMPATIBLE, ANALOG-TO-DIGITAL CONVERTERS WITH FIFO INTERNAL REFERENCE AND PGA
SLAS285 – JUNE 2000
PARAMETER MEASUREMENT INFORMATION
read timing (15-pF load)
PARAMETER MIN TYP MAX UNIT
t
su(OE–ACS)
t
en
t
dis
t
h(A)
t
h(CS)
NOTE: All timing parameters refer to a 50% level.
CS
OE
Address and chip select setup time 4 ns Output enable 15 ns Output disable 10 ns Address hold time 1 15 ns Chip select hold time 0 ns
t
h(CS)
D[13:0]
O V
A[1:0]
t
su(OE–ACS)
X X
t
en
DATA
ADDRESS
Figure 3. Read Timing
t
h(A)
t
dis
8
POST OFFICE BOX 655303 DALLAS, TEXAS 75265
14-BIT, 1 MSPS/ 3 MSPS, DSP COMPATIBLE, ANALOG-TO-DIGITAL CONVERTERS
PARAMETER MEASUREMENT INFORMATION
write timing (15-pF load)
PARAMETER MIN TYP MAX UNIT
t
su(WE–CS)
t
su(DA)
t
h(DA)
t
h(CS)
t
wH(WE)
NOTE: All timing parameters refer to a 50% level.
CS
WE
Chip select setup time 4 ns Data and address setup time 29 ns Data and address hold time 0 ns Chip select hold time 0 ns Write pulse duration high 15 ns
t
su(WE–CS)
THS14F01, THS14F03
WITH FIFO INTERNAL REFERENCE AND PGA
SLAS285 – JUNE 2000
t
h(CS)
t
su(DA)
D[13:0]
t
h(DA)
X
X
A
X X
DATA
ADDRESS
Figure 4. Write Timing
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THS14F01, THS14F03 14-BIT, 1 MSPS/ 3 MSPS, DSP COMPATIBLE, ANALOG-TO-DIGITAL CONVERTERS WITH FIFO INTERNAL REFERENCE AND PGA
SLAS285 – JUNE 2000
TYPICAL CHARACTERISTICS
POWER
vs
FREQUENCY
284
282
280
278
276
Power – mW
274
272
270
268
0.1 1 10 f – Frequency – MHz
Figure 5
0
fs = 1 MSPS,
–20
fI = 100 kHz, –1 dB
–40 –60
90
80
70
60
50
40
30
– Supply Current – mA
CC
I
20
10
0
0 50 100 150 200 250 300
FAST FOURIER TRANSFORM
SUPPLY CURRENT
vs
TIME
t – Time – ns
Figure 6
10
–80
Output – dB
–100 –120
–140
0 100 200 300
f – Frequency – kHz
Figure 7
POST OFFICE BOX 655303 DALLAS, TEXAS 75265
400 500
THS14F01, THS14F03
14-BIT, 1 MSPS/ 3 MSPS, DSP COMPATIBLE, ANALOG-TO-DIGITAL CONVERTERS
WITH FIFO INTERNAL REFERENCE AND PGA
SLAS285 – JUNE 2000
TYPICAL CHARACTERISTICS
FAST FOURIER TRANSFORM
0
fs = 3 MSPS,
–20
fI = 1 MHz, –1 dB
–40 –60 –80
Output – dB
–100 –120
–140
0.1 0.4 0.7 1 f – Frequency – MHz
Figure 8
INTEGRAL NONLINEARITY
2
1.5
0.5
–0.5
–1
–1.5
–2
INL – Integral Nonlinearity – LSB
fs = 1 MSPS
1
0
0 2048 4096 6144 8192 10240
Samples
12288 14336 16384
1.3
Figure 9
INTEGRAL NONLINEARITY
2
1.5 1
0.5 0
–0.5
–1
–1.5
–2
INL – Integral Nonlinearity – LSB
0 2048 4096 6144 8192 10240
Samples
Figure 10
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fs = 3 MSPS
12288 14336 16384
11
THS14F01, THS14F03 14-BIT, 1 MSPS/ 3 MSPS, DSP COMPATIBLE, ANALOG-TO-DIGITAL CONVERTERS WITH FIFO INTERNAL REFERENCE AND PGA
SLAS285 – JUNE 2000
TYPICAL CHARACTERISTICS
DIFFERENTIAL NONLINEARITY
1
fs = 1 MSPS
0.8
0.6
0.4
0.2 0
–0.2 –0.4 –0.6 –0.8
–1
0 2048 4096 6144 8192 10240
DNL – Differential Nonlinearity – LSB
Samples
Figure 11
DIFFERENTIAL NONLINEARITY
1
0.8
0.6
0.4
0.2 0
–0.2 –0.4 –0.6 –0.8
–1
0 2048 4096 6144 8192 10240
DNL – Differential Nonlinearity – LSB
Samples
12288 14336 16384
fs = 3 MSPS
12288 14336 16384
12
Figure 12
POST OFFICE BOX 655303 DALLAS, TEXAS 75265
THS14F01, THS14F03
14-BIT, 1 MSPS/ 3 MSPS, DSP COMPATIBLE, ANALOG-TO-DIGITAL CONVERTERS
WITH FIFO INTERNAL REFERENCE AND PGA
SLAS285 – JUNE 2000
TYPICAL CHARACTERISTICS
TOTAL HARMONIC DISTORTION
FREQUENCY
–70
fs = 3 MSPS,
–72
fI at –1 dB –74
–76 –78 –80
–82
–84 –86
THD – Total Harmonic Distortion – dB
–88 –90
10
f – Frequency – Hz
Figure 13 Figure 14
vs
100 1000
1500
SIGNAL-TO-NOISE RATIO
FREQUENCY
80
fs = 3 MSPS,
78
fI at –1 dB
76
74 72 70
68
66 64
SNR – Signal-to-Noise Ratio – dB
62 60
10
100
f – Frequency – Hz
vs
1000
1500
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THS14F01, THS14F03 14-BIT, 1 MSPS/ 3 MSPS, DSP COMPATIBLE, ANALOG-TO-DIGITAL CONVERTERS WITH FIFO INTERNAL REFERENCE AND PGA
SLAS285 – JUNE 2000
PRINCIPLES OF OPERATION
registers
The device contains several registers. The A register is selected by the values of bits A1 and A0:
A1 A0 Register
0 0 Conversion result 0 1 PGA 1 0 Offset 1 1 Control
T ables 1 and 2 describe how to read the conversion results and how to configure the data converter . The default values (were applicable) show the state after a power-on reset.
Table 1. Conversion Result Register, Address 0, Read
BIT D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
Function MSB ... LSB
The output can be configured for two’s complement or straight binary format (see D11/control register). The output code is given by:
2s complement: Straight binary: –8192 at ∆IN = –∆REF 0 at ∆IN = –∆REF 0 at IN = 0 8192 at IN = 0 8191 IN = –REF – 1 LSB 16383 at IN = –REF – 1 LSB
1LSB
+
2DREF
16384
Table 2. PGA Gain Register, Address 1, Read/Write
BIT D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
Function X X X X X X X X X X X G2 G1 G0
Default 0 0 0 0 0 0 0 0 0 0 0 0 0 0
The PGA gain is determined by writing to G2–0. Gain (dB) = 1dB × G2–0. max = 7dB. The range of G2–0 is 0 to 7.
Table 3. Offset Register, Address 2, Read/Write
BIT D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
Function X X X X X X MSB LSB
Default 0 0 0 0 0 0 0 0 0 0 0 0 0 0
The offset correction range is from –128 to 127 LSB. This value is added to the conversion results from the ADC.
14
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THS14F01, THS14F03
14-BIT, 1 MSPS/ 3 MSPS, DSP COMPATIBLE, ANALOG-TO-DIGITAL CONVERTERS
WITH FIFO INTERNAL REFERENCE AND PGA
SLAS285 – JUNE 2000
PRINCIPLES OF OPERATION
Table 4. Control Register, Address 3, Read
BIT D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
Function PWD REF FOR TM2 TM1 TM0 OFF IP FP FC F3 F2 F1 F0
Table 5. Control Register, Address 3, Write
BIT D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
Function PWD REF FOR TM2 TM1 TM0 OFF IP FP FC F3 F2 F1 F0
Default 0 0 0 0 0 0 0 0 0 0 0 0 0 0
PWD: Power down 0 = normal operation 1 = power down REF: Reference select 0 = internal reference 1 = external reference FOR: Output format 0 = straight binary 1 = 2s complement TM2–0: Test mode 000 = normal operation
001 = both inputs = REF– 010 = IN+ at V 011 = IN+ at REF+, IN– at REF– 100 = normal operation 101 = both inputs = REF+ 110 = IN+ at REF–, IN– at V
111 = IN+ at REF–, IN– at REF+ OFF: Offset correction 0 = enable 1 = disable IP: INT polarity 0 = low active 1 = high active FP: FIFO FOVL polarity 0 = low active 1 = high active FC: FIFO control 0 = disable FIFO 1 = enable FIFO F3–0: FIFO threshold Sets the FIFO threshold for the INT signal in steps of 2 ranging from 0 to 30
/2, IN– at REF–
ref
ref
/2
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THS14F01, THS14F03 14-BIT, 1 MSPS/ 3 MSPS, DSP COMPATIBLE, ANALOG-TO-DIGITAL CONVERTERS WITH FIFO INTERNAL REFERENCE AND PGA
SLAS285 – JUNE 2000
APPLICATION INFORMATION
FIFO description
The FIFO is based on a circular buffer (see Figure 15, in this example the FIFO is 16 words long). The buffer is accessed using two pointers, one for the ADC writing to the FIFO, one for the processor (DSP) reading from the buffer . Both pointers move in a clockwise direction. If the distance between the ADC write pointer and the DSP read pointer is greater or equal a programmable threshold, the INT signal is asserted. If this INT signal is connected to an external interrupt pin of the processor, it is possible to read out the stored values in the FIFO at once during the interrupt service routine. If the ADC write pointer reaches the position of the DSP read pointer, an overflow occurs. In this case, the overflow bit in the ADC register is set and the FOVL is asserted.
12
15
14
13
ADC
11
10
9
8
0
1
2
DSP
3
4
T
5
6
7
16
Figure 15. Circular Buffer
POST OFFICE BOX 655303 DALLAS, TEXAS 75265
THS14F01, THS14F03
14-BIT, 1 MSPS/ 3 MSPS, DSP COMPATIBLE, ANALOG-TO-DIGITAL CONVERTERS
WITH FIFO INTERNAL REFERENCE AND PGA
SLAS285 – JUNE 2000
APPLICATION INFORMATION
DMA transfer and FIFO
The FIFO makes it possible to use the available interface bandwidth of the host processor more efficiently . The following is a description based on the TMS320C6201 DSP from TI.
The TMS320C6201 memory interface has a limited bandwidth, for example 200MWPS at a clock rate of 200 MHz. The THS14F04x interface is asynchronous with a maximum speed of 300MWPS, which is approximately 7 clock cycles.
If the DSP uses the DMA controller to read data from the DSP, the following conditions exist:
DMA bus arbitration: 16 clock cycles
THS14F0x read access: 7 clock cycles
If, for example, 10 samples need to be read from the ADC without the FIFO, the memory interface will be allocated for (10 + 7) × 16 = 272 clock cycles in total.
BUSarb R
S
BUSarb R
S
BUSarb R
S
BUSarb R
S
BUSarb R
S
With a FIFO programmed to a 10 sample threshold, the memory interface will be allocated for 16 + 7 × 10 = 86 clock cycles in total.
BUS Available for Other Peripheral
BUSarb R R R R BUSarb R R R R
driving the analog input
The THS14F01/3 ADCs have a fully differential input. A differential input is advantageous with respect to SNR, SFDR, and THD performance because the signal peak-to-peak level is 50% of a comparable single-ended input.
There are three basic input configurations:
Fully differential
Transformer coupled single-ended to differential
Single-ended
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THS14F01, THS14F03 14-BIT, 1 MSPS/ 3 MSPS, DSP COMPATIBLE, ANALOG-TO-DIGITAL CONVERTERS WITH FIFO INTERNAL REFERENCE AND PGA
SLAS285 – JUNE 2000
APPLICATION INFORMATION
fully differential configuration
In this configuration, the ADC converts the difference (∆IN) of the two input signals on IN+ and IN–.
22
100 pF
22
100 pF
Figure 16. Differential Input
The resistors and capacitors on the inputs decouple the driving source output from the ADC input and also serve as first order low pass filters to attenuate out of band noise.
The input range on both inputs is 0 V to A VDD. The full-scale value is determined by the voltage reference. The positive full-scale output is reached, if IN equals REF , the negative full-scale output is reached, if IN equals –REF.
IN [V] OUTPUT
REF – full scale
0 0
REF + full scale
IN+
THS14F01/3
IN–
transformer coupled single-ended to differential configuration
If the application requires the best SNR, SFDR, and THD performance, the input should be transformer coupled. The signal amplitude on both inputs of the ADC is one half as high as in a single-ended configuration thus
increasing the ADC ac performance.
22
100 pF
R
22
100 pF
+
1 µF 0.1 µF
Figure 17. Transformer Coupled
IN [V
REF – full scale
n = 1 (winding ratio)
] OUTPUT [
PEAK
0 0
REF + full scale
The resistor R of the transformer coupled input configuration must be set to match the signal source impedance R = n2 Rs, where Rs is the source impedance and n is the transformer winding ratio.
IN+
THS14F01/3
IN–
CML
]
PEAK
18
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14-BIT, 1 MSPS/ 3 MSPS, DSP COMPATIBLE, ANALOG-TO-DIGITAL CONVERTERS
APPLICATION INFORMATION
single-ended configuration
In this configuration, the input signal is level shifted by ∆REF/2.
10 k 10 kΩ
– +
22
THS14F01, THS14F03
WITH FIFO INTERNAL REFERENCE AND PGA
SLAS285 – JUNE 2000
10 kΩ + 10 k
REF+
100 pF
100 pF
IN+
THS14F01/3
IN–
REF–
10 k
10 k
Figure 18. Single-Ended With Level Shift
The following table shows the input voltages for negative full-scale output, zero output, and positive full-scale output:
IN+ [V] OUTPUT
REF – full scale
0 0
REF + full scale
Note that the resistors of the op-amp and the op-amp all introduce gain and offset errors. Those errors can be trimmed by varying the values of the resistors.
Because of the added offset, the op-amp does not necessarily operate in the best region of its transfer curve (best linearity around zero) and therefore may introduce unacceptable distortion. For ac signals, an alternative is described in the following section.
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19
THS14F01, THS14F03 14-BIT, 1 MSPS/ 3 MSPS, DSP COMPATIBLE, ANALOG-TO-DIGITAL CONVERTERS WITH FIFO INTERNAL REFERENCE AND PGA
SLAS285 – JUNE 2000
APPLICATION INFORMATION
ac-coupled single-ended configuration
If the application does not require the signal bandwidth to include dc, the level shift shown in Figure 4 is not necessary.
10 k 10 k
REF+
10 k 10 kΩ
+
100 pF
10 nF
22
100 pF
Figure 19. Single-Ended With Level Shift
IN+
THS14F01/3
IN–
10 k 10 k
REF–
Because the signal swing on the op-amp is centered around ground, it is more likely that the signal stays within the linear region of the op-amp transfer function, thus increasing the overall ac performance.
IN [V
REF – full scale
] OUTPUT [
PEAK
0 0
REF + full scale
PEAK
]
Compared to the transformer-coupled configuration, the swing on IN– is twice as big, which can decrease the ac performance (SNR, SFD, and THD).
20
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THS14F01, THS14F03
14-BIT, 1 MSPS/ 3 MSPS, DSP COMPATIBLE, ANALOG-TO-DIGITAL CONVERTERS
WITH FIFO INTERNAL REFERENCE AND PGA
SLAS285 – JUNE 2000
APPLICATION INFORMATION
internal/external reference operation
The THS14F01/3 ADC can either be operated using the built-in band gap reference or using an external precision reference in case very high dc accuracy is needed.
The REF+ and REF+ outputs are given by:
REF
)+
If the built-in reference is used, VBG equals 1.5 V which results in REF+ = 2.5 V, REF– = 0.5 V and REF = 2V.
The internal reference can be disabled by writing 1 to D12 (REF) in the control register (address 3). The band gap reference is then disconnected and can be substituted by a voltage on the VBG pin.
VBG
ǒ
Ǔ
1
)
and REF–+VBGǒ1–
3
2
2
Ǔ
3
programmable gain amplifier
The on-chip programmable gain amplifier (PGA) has eight gain settings. The gain can be changed by writing to the PGA gain register (address 1). The range is 0 to 7dB in steps of one dB.
out of range indication
The OV output of the ADC indicates an out of range condition. Every time the difference on the analog inputs exceeds the differential reference, this signal is asserted. This signal is updated the same way as the digital data outputs and therefore subject to the same pipeline delay.
offset compensation
With the offset register it is possible to automatically compensate system offset errors, including errors caused by additional signal conditioning circuitry . If the offset compensation is enabled (D7 (OFF) in the control register), the value in the offset register (address 2) is automatically subtracted from the output of the ADC.
In order to set the correct value of the offset compensation register , the ADC result when the input signal is 0 must be read by the host processor and written to the offset register (address 2).
test modes
The ADC core operation can be tested by selecting one of the available test modes (see control register description). The test modes apply various voltages to the differential input depending on the setting in the control register.
digital I/O
The digital inputs and outputs of the THS14F01/3 ADC are 3-V CMOS compatible. In order to avoid current feed back errors, the capacitive load on the digital outputs should be as low as possible (50 pF max). Series resistors (100 Ω) on the digital outputs can improve the performance by limiting the current during output transitions.
The parallel interface of the THS14F01/3 ADC features 3-state buffers, making it possible to directly connect it to a data bus. The output buffers are enabled by driving the OE input low.
Refer to the read and write timing diagrams in the parameter measurement information section for information on read and write access.
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THS14F01, THS14F03 14-BIT, 1 MSPS/ 3 MSPS, DSP COMPATIBLE, ANALOG-TO-DIGITAL CONVERTERS WITH FIFO INTERNAL REFERENCE AND PGA
SLAS285 – JUNE 2000
MECHANICAL DATA
PFB (S-PQFP-G48) PLASTIC QUAD FLATPACK
37
48
1,05 0,95
0,50
36
0,27 0,17
25
24
13
1
5,50 TYP
7,20
SQ
6,80 9,20
SQ
8,80
12
M
0,08
0,05 MIN
Seating Plane
0,13 NOM
Gage Plane
0,25
0°–7°
0,75 0,45
1,20 MAX
NOTES: A. All linear dimensions are in millimeters.
22
B. This drawing is subject to change without notice. C. Falls within JEDEC MS-026
POST OFFICE BOX 655303 DALLAS, TEXAS 75265
0,08
4073176/B 10/96
IMPORTANT NOTICE
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