Datasheet

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LTC1604

1604fa

TYPICAL APPLICATION

FEATURES DESCRIPTION

High Speed, 16-Bit, 333ksps

Sampling A/D Converter

with Shutdown

The LTC

1604 is a 333ksps, 16-bit sampling A/D con-

verter that draws only 220mW from ±5V supplies. This

high performance device includes a high dynamic range

sample-and-hold, a precision reference and a high speed

parallel output. Two digitally selectable power shutdown

modes provide power savings for low power systems.

The LTC1604’s full-scale input range is ±2.5V. Outstand-

ing AC performance includes 90dB S/(N+D) and –100dB

THD at a sample rate of 333ksps.

The unique differential input sample-and-hold can acquire

single-ended or differential input signals up to its 15MHz

bandwidth. The 68dB common mode rejection allows

users to eliminate ground loops and common mode noise

by measuring signals differentially from the source.

The ADC has μP compatible,16-bit parallel output port.

There is no pipeline delay in conversion results. A separate

convert start input and a data ready signal (BUSY) ease

connections to FlFOs, DSPs and microprocessors.

LTC1604 4096 Point FFT

APPLICATIONS

A Complete, 333ksps 16-Bit ADC

90dB S/(N+D) and –100dB THD (Typ)

Power Dissipation: 220mW (Typ)

No Pipeline Delay

No Missing Codes over Temperature

Nap (7mW) and Sleep (10μW) Shutdown Modes

Operates with Internal 15ppm/°C Reference

or External Reference

True Differential Inputs Reject Common Mode Noise

5MHz Full Power Bandwidth

±2.5V Bipolar Input Range

36-Pin SSOP Package

Telecommunications

Digital Signal Processing

Multiplexed Data Acquisition Systems

High Speed Data Acquisition

Spectrum Analysis

Imaging Systems

L, LTC and LT are registered trademarks of Linear Technology Corporation.

2.2μF

10μF

10Ω

47μF

DIFFERENTIAL

ANALOG INPUT

±2.5V

REFCOMP

4.375V

CONTROL

LOGIC

AND

TIMING

B15 TO B0

16-BIT

SAMPLING

ADC

–

10μF

5V OR

μP

CONTROL

LINES

D15 TO D0

OUTPUT

BUFFERS

16-BIT

PARALLEL

BUS

11 TO 26

1604 TA01

OGND

–

SHDN

CONVST

BUSY

7.5k

DGND

REF

AGND

–5V

10μF

2.5V

REF

10μF

1.75X

+ +

FREQUENCY (kHz)

AMPLITUDE (dB)

120

1604 TA02

40 80 160

–20

–40

–60

–80

–100

–120

–140

20 60 100 140

SAMPLE

= 333kHz

= 100kHz

SINAD = 89dB

THD = –96dB

Summary of content (20 pages)

PAGE 1
LTC1604 High Speed, 16-Bit, 333ksps Sampling A/D Converter with Shutdown DESCRIPTION FEATURES n n n n n n n n n n n A Complete, 333ksps 16-Bit ADC 90dB S/(N+D) and –100dB THD (Typ) Power Dissipation: 220mW (Typ) No Pipeline Delay No Missing Codes over Temperature Nap (7mW) and Sleep (10μW) Shutdown Modes Operates with Internal 15ppm/°C Reference or External Reference True Differential Inputs Reject Common Mode Noise 5MHz Full Power Bandwidth ±2.
PAGE 2
LTC1604 ABSOLUTE MAXIMUM RATINGS PACKAGE/ORDER INFORMATION AVDD = DVDD = OVDD = VDD (Notes 1, 2) ORDER PART NUMBER TOP VIEW Supply Voltage (VDD) ..................................................6V Negative Supply Voltage (VSS) ..................................–6V Total Supply Voltage (VDD to VSS) ............................12V Analog Input Voltage (Note 3) ..........................(VSS – 0.3V) to (VDD + 0.3V) VREF Voltage (Note 4)................... –0.3V to (VDD + 0.3V) REFCOMP Voltage (Note 4)...
PAGE 3
LTC1604 DYNAMIC ACCURACY (Note 5) SYMBOL PARAMETER CONDITIONS S/N 5kHz Input Signal 100kHz Input Signal Signal-to-Noise Ratio S/(N + D) Signal-to-(Noise + Distortion) Ratio THD Total Harmonic Distortion Up to 5th Harmonic LTC1604 MIN TYP MAX l 90 90 5kHz Input Signal 100kHz Input Signal (Note 10) l 90 89 5kHz Input Signal 100kHz Input Signal l –100 –94 LTC1604A MIN TYP MAX 87 84 UNITS 90 90 dB dB 90 89 dB dB –100 –94 –88 dB dB SFDR Spurious Free Dynamic Range 100kHz Input Signal
PAGE 4
LTC1604 POWER REQUIREMENTS (Note 5) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS VDD Positive Supply Voltage (Notes 12, 13) 4.75 5.25 V VSS Negative Supply Voltage (Note 12) –4.75 –5.25 V IDD Positive Supply Current Nap Mode Sleep Mode CS = RD = 0V CS = 0V, SHDN = 0V CS = 5V, SHDN = 0V l 18 1.5 1 30 2.
PAGE 5
LTC1604 TIMING CHARACTERISTICS (Note 5) The l denotes specifications that apply over the full operating temperature range. Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: All voltage values are with respect to ground with DGND, OGND and AGND wired together unless otherwise noted. Note 3: When these pin voltages are taken below VSS or above VDD, they will be clamped by internal diodes.
PAGE 6
LTC1604 TYPICAL PERFORMANCE CHARACTERISTICS Power Supply Feedthrough vs Ripple Frequency 0 fSAMPLE = 333kHz fIN1 = 29.3kHz fIN2 = 32.
PAGE 7
LTC1604 FUNCTIONAL BLOCK DIAGRAM 10μF 2.2μF 10Ω + 3 VREF 5V 10μF + 36 AVDD 5V 35 9 AVDD 10μF + 10 DVDD DGND SHDN 33 4 REFCOMP + 7.5k 1.75X 4.375V CS 32 CONTROL LOGIC AND TIMING 2.5V REF μP CONTROL LINES CONVST 31 RD 30 BUSY 27 47μF OVDD 29 + 1 AIN+ DIFFERENTIAL ANALOG INPUT ±2.
PAGE 8
LTC1604 APPLICATIONS INFORMATION CONVERSION DETAILS The LTC1604 uses a successive approximation algorithm and internal sample-and-hold circuit to convert an analog signal to a 16-bit parallel output. The ADC is complete with a sample-and-hold, a precision reference and an internal clock. The control logic provides easy interface to microprocessors and DSPs. (Please refer to the Digital Interface section for the data format.) Conversion start is controlled by the CS and CONVST inputs.
PAGE 9
LTC1604 APPLICATIONS INFORMATION currents are shut down and only leakage current remains (about 1μA). Wake-up time from Sleep mode is much slower since the reference circuit must power up and settle. Sleep mode wake-up time is dependent on the value of the capacitor connected to the REFCOMP (Pin 4). The wake-up time is 160ms with the recommended 47μF capacitor. SHDN t3 CS 1604 F02a Figure 2a. Nap Mode to Sleep Mode Timing Shutdown is controlled by Pin 33 (SHDN). The ADC is in shutdown when SHDN is low.
PAGE 10
LTC1604 APPLICATIONS INFORMATION t CONV CS = RD = 0 t5 CONVST t6 t8 BUSY t7 DATA DATA (N + 1) D15 TO D0 DATA N D15 TO D0 DATA (N – 1) D15 TO D0 1604 F05 Figure 5. Mode 1a. CONVST Starts a Conversion. Data Outputs Always Enabled (CONVST = ) CS = RD = 0 tCONV t8 t5 t13 CONVST t6 t6 BUSY t7 DATA (N – 1) D15 TO D0 DATA DATA N D15 TO D0 DATA (N + 1) D15 TO D0 1604 F06 Figure 6. Mode 1b. CONVST Starts a Conversion.
PAGE 11
LTC1604 APPLICATIONS INFORMATION CS = 0 t8 t CONV RD = CONVST t6 t 11 BUSY t 10 t7 DATA (N – 1) D5 TO D0 DATA DATA N D15 TO D0 DATA N D15 TO D0 DATA (N + 1) D15 TO D0 1604 F08 Figure 8. Mode 2. Slow Memory Mode Timing t CONV CS = 0 t8 RD = CONVST t6 t 11 BUSY t 10 DATA DATA N D15 TO D0 DATA (N – 1) D15 TO D0 1604 F09 Figure 9. ROM Mode Timing in three-state until read by the MPU with the RD signal. Mode 2 can be used for operation with a shared data bus.
PAGE 12
LTC1604 ACQUISITION TIME (μs) APPLICATIONS INFORMATION 10 LT®1007: Low Noise Precision Amplifier. 2.7mA supply current, ±5V to ±15V supplies, gain bandwidth product 8MHz, DC applications. 1 LT1097: Low Cost, Low Power Precision Amplifier. 300μA supply current, ±5V to ±15V supplies, gain bandwidth product 0.7MHz, DC applications. 0.1 LT1227: 140MHz Video Current Feedback Amplifier. 10mA supply current, ±5V to ±15V supplies, low noise and low distortion. 0.
PAGE 13
LTC1604 APPLICATIONS INFORMATION 100Ω ANALOG INPUT 3000pF 1 AIN+ 2.500V 2 3 4 R1 7.5k 3 VREF AIN– LTC1604 VREF 4.375V 4 REFCOMP REFERENCE AMP REFCOMP R2 12k 47μF 47μF 5 BANDGAP REFERENCE AGND 1604 F11 R3 16k 5 AGND LTC1604 Figure 11. RC Input Filter 1604 F12a Figure 12a. LTC1604 Reference Circuit Input Range The ±2.5V input range of the LTC1604 is optimized for low noise and low distortion.
PAGE 14
LTC1604 APPLICATIONS INFORMATION 1 ANALOG INPUT 2V TO 2.7V DIFFERENTIAL 2 AIN+ ANALOG INPUT AIN– 0V TO 5V ±2.5V + LTC1604 LTC1450 2V TO 2.7V 3 4 1 AIN+ 2 AIN– 3 VREF – VREF LTC1604 4 REFCOMP REFCOMP 10μF 47μF 5 5 AGND AGND 1604 F14b 1604 F13 Figure 14b. Selectable 0V to 5V or ±2.5V Input Range 80 Full-Scale and Offset Adjustment 70 Figure 15a shows the ideal input/output characteristics for the LTC1604.
PAGE 15
LTC1604 APPLICATIONS INFORMATION –5V ANALOG INPUT R3 24k R8 50k 1 AIN+ 2 AIN– R4 100Ω 3 R5 R7 47k 50k R6 24k + 47μF 0.1μF 4 5 LTC1604 VREF REFCOMP AGND 1604 F15b Figure 15b. Offset and Full-Scale Adjust Circuit –38μV (i.e., –0.5LSB) at AIN+ and adjust the offset at the AIN– input until the output code flickers between 0000 0000 0000 0000 and 1111 1111 1111 1111. For full-scale adjustment, an input voltage of 2.499886V (FS/2 – 1.
PAGE 16
LTC1604 APPLICATIONS INFORMATION 1 ANALOG INPUT CIRCUITRY + – AIN+ AIN– 2 DIGITAL SYSTEM LTC1604 VREF REFCOMP AGND 3 4 2.2μF 47μF 5 TO 8 VSS AVDD AVDD DVDD DGND OVDD OGND 34 36 35 9 10μF 10μF 10μF 10μF 10 29 28 10μF 1604 F16 Figure 16. Power Supply Grounding Practice DC PERFORMANCE 2000 COUNT 1500 1000 500 0 –5 –4 –3 –2 –1 0 1 CODE 2 3 4 5 1604 F17 Figure 17. Histogram for 4096 Conversions 0 fSAMPLE = 333kHz fIN = 4.959kHz SINAD = 90.2dB THD = –103.
PAGE 17
LTC1604 APPLICATIONS INFORMATION 0 Signal-to-Noise Ratio –40 AMPLITUDE (dB) The signal-to-noise plus distortion ratio [S/(N + D)] is the ratio between the RMS amplitude of the fundamental input frequency to the RMS amplitude of all other frequency components at the A/D output. The output is band limited to frequencies from above DC and below half the sampling frequency. Figure 18a shows a typical spectral content with a 333kHz sampling rate and a 5kHz input.
PAGE 18
LTC1604 APPLICATIONS INFORMATION Intermodulation Distortion If the ADC input signal consists of more than one spectral component, the ADC transfer function nonlinearity can produce intermodulation distortion (IMD) in addition to THD. IMD is the change in one sinusoidal input caused by the presence of another sinusoidal input at a different frequency.
PAGE 19
LTC1604 PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted. G Package 36-Lead Plastic SSOP (0.209) (LTC DWG # 05-08-1640) 0.499 – 0.509* (12.67 – 12.93) 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 0.301 – 0.311 (7.65 – 7.90) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 0.205 – 0.212** (5.20 – 5.38) 0.068 – 0.078 (1.73 – 1.99) 0° – 8° 0.005 – 0.009 (0.13 – 0.22) 0.022 – 0.037 (0.55 – 0.95) *DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.
PAGE 20
LTC1604 TYPICAL APPLICATION Using the LTC1604 and Two LTC1391s as an 8-Channel Differential 16-Bit ADC System 5V 1 2 3 4 5 6 7 CH7 + 8 CH0 V+ D CH1 CH2 V DOUT CH4 DIN CH5 CS CH6 CLK CH7 GND 2 3 4 5 6 7 CH7 – 8 V+ CH1 D CH2 V– CH3 DOUT CH4 DIN CH5 CS CH6 CLK CH7 GND 10 9 DVDD AVDD DGND SHDN 33 + 13 1μF 4 REFCOMP 12 + 4.375V 47μF 11 7.5k 1.75X 10 2.