Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsData collecting ICsData acquisition IC - AD converter (ADC) External , Internal SSOP 36

1603f

LTC1603

High Speed, 16-Bit, 250ksps

Sampling A/D Converter

with Shutdown

The LTC

1603 is a 250ksps, 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 LTC1603’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 250ksps.

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.

■

A Complete, 250ksps 16-Bit ADC

■

90dB S/(N+D) and –100dB THD (Typ)

■

Power Dissipation: 220mW (Typ)

■

Nap (7mW) and Sleep (10

W) Shutdown Modes

■

No Pipeline Delay

■

No Missing Codes over Temperature

■

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

■

Pin Compatible with LTC1604 and LTC1608

■

36-Pin SSOP Package

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

■

Telecommunications

■

Digital Signal Processing

■

Multiplexed Data Acquisition Systems

■

High Speed Data Acquisition

■

Spectrum Analysis

■

Imaging Systems

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

1603 TA01

OGND

–

SHDN

CONVST

BUSY

7.5k

DGND

REF

AGND

–5V

10µF

2.5V

REF

10µF

1.75X

+ +

FEATURES

DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO

Summary of content (20 pages)

PAGE 1
LTC1603 High Speed, 16-Bit, 250ksps Sampling A/D Converter with Shutdown DESCRIPTIO U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ The LTC®1603 is a 250ksps, 16-bit sampling A/D converter 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.
PAGE 2
LTC1603 W U U U W W W 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.
PAGE 3
LTC1603 W U DY A IC ACCURACY The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C.
PAGE 4
LTC1603 U W POWER REQUIRE E TS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 5) SYMBOL PARAMETER CONDITIONS MIN MAX UNITS VDD Positive Supply Voltage (Notes 12, 13) 4.75 TYP 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 ● 18 1.5 1 30 2.
PAGE 5
LTC1603 WU TI I G CHARACTERISTICS (Note 5) 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. This product can handle input currents greater than 100mA below VSS or above VDD without latchup.
PAGE 6
LTC1603 U U U PIN FUNCTIONS AIN+ (Pin 1): Positive Analog Input. The ADC converts the difference voltage between AIN+ and AIN– with a differential range of ±2.5V. AIN+ has a ±2.5V input range when AIN– is grounded. OVDD (Pin 29): Digital Power Supply for Output Drivers. Bypass to OGND with 10µF tantalum in parallel with 0.1µF ceramic. AIN– (Pin 2): Negative Analog Input. Can be grounded, tied to a DC voltage or driven differentially with AIN+ . RD (Pin 30): Read Input.
PAGE 7
LTC1603 W FU CTIO AL BLOCK DIAGRA U 10µF U 2.2µF 10Ω + 3 VREF 5V 10µF 5V + 36 35 9 AVDD 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
LTC1603 U U W U APPLICATIONS INFORMATION CONVERSION DETAILS The LTC1603 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
LTC1603 U W U U 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 1603 F02a Figure 2a. Nap Mode to Sleep Mode Timing Shutdown is controlled by Pin 33 (SHDN).
PAGE 10
LTC1603 U W U U 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 1603 F05 Figure 5. Mode 1a. CONVST Starts a Conversion. Data Outputs Always Enabled (CONVST = ) tCONV CS = RD = 0 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 1603 F06 Figure 6. Mode 1b. CONVST Starts a Conversion.
PAGE 11
LTC1603 U U W U APPLICATIONS INFORMATION t8 t CONV CS = 0 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 1603 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 1603 F09 Figure 9. ROM Mode Timing 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
LTC1603 U W U U APPLICATIONS INFORMATION ACQUISITION TIME (µs) 10 LT ® 1007: Low Noise Precision Amplifier. 2.7mA supply current, ±5V to ±15V supplies, gain bandwidth product 8MHz, DC applications. 1 0.1 LT1097: Low Cost, Low Power Precision Amplifier. 300µA supply current, ±5V to ±15V supplies, gain bandwidth product 0.7MHz, DC applications. 0.01 LT1227: 140MHz Video Current Feedback Amplifier. 10mA supply current, ±5V to ±15V supplies, low noise and low distortion.
PAGE 13
LTC1603 U U W U APPLICATIONS INFORMATION 100Ω ANALOG INPUT 3000pF 1 AIN+ 2.500V 2 R1 7.5k 3 VREF BANDGAP REFERENCE AIN– LTC1603 3 4 VREF 4.375V 4 REFCOMP REFERENCE AMP REFCOMP R2 12k 47µF 47µF 5 AGND 1603 F11 R3 16k 5 AGND LTC1603 1603 F12a Figure 11. RC Input Filter Figure 12a. LTC1603 Reference Circuit Input Range The ±2.5V input range of the LTC1603 is optimized for low noise and low distortion.
PAGE 14
LTC1603 U U W U APPLICATIONS INFORMATION 1 ANALOG INPUT 2V TO 2.7V DIFFERENTIAL 2 AIN+ ANALOG INPUT – AIN 0V TO 5V ±2.5V LTC1603 LTC1450 2V TO 2.7V 3 4 + 1 AIN+ 2 AIN– 3 VREF – VREF LTC1603 4 REFCOMP REFCOMP 10µF 47µF 5 5 AGND AGND 1603 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 LTC1603.
PAGE 15
LTC1603 U W U U APPLICATIONS INFORMATION –5V ANALOG INPUT R3 24k R8 50k 1 AIN+ 2 AIN– R4 100Ω 3 R5 R7 47k 50k R6 24k + 47µF 4 LTC1603 VREF REFCOMP 0.1µF 5 AGND 1603 F15b Figure 15b. Offset and Full-Scale Adjust Circuit – 38µV (i.e., – 0.5LSB) at AIN+ and adjust the offset at the AIN– input by varying R8 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
LTC1603 U U W U APPLICATIONS INFORMATION 1 AIN+ DIGITAL SYSTEM LTC1603 – ANALOG INPUT CIRCUITRY 2 + – AIN V REF REFCOMP AGND 3 4 2.2µF 47µF 5 TO 8 VSS AVDD AVDD DGND OVDD OGND DVDD 34 36 35 9 10µF 10µF 10µF 10µF 10 29 28 10µF 1603 F16 Figure 16. Power Supply Grounding Practice DC PERFORMANCE COUNT 2000 1500 1000 500 0 –5 –4 –3 –2 –1 0 1 CODE 2 3 4 5 1603 F17 Figure 17. Histogram for 4096 Conversions 0 fSAMPLE = 250kHz fIN = 9.959kHz SINAD = 90.
PAGE 17
LTC1603 U W U U 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 250kHz sampling rate and a 5kHz input.
PAGE 18
LTC1603 U U W U 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
LTC1603 U PACKAGE DESCRIPTION G Package 36-Lead Plastic SSOP (5.3mm) (Reference LTC DWG # 05-08-1640) 12.50 – 13.10* (.492 – .516) 1.25 ±0.12 7.8 – 8.2 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 5.3 – 5.7 7.40 – 8.20 (.291 – .323) 0.42 ±0.03 0.65 BSC 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 RECOMMENDED SOLDER PAD LAYOUT 5.00 – 5.60** (.197 – .221) 2.0 (.079) 0° – 8° 0.09 – 0.25 (.0035 – .010) 0.55 – 0.95 (.022 – .037) NOTE: 1. CONTROLLING DIMENSION: MILLIMETERS MILLIMETERS 2.
PAGE 20
LTC1603 U TYPICAL APPLICATION Using the LTC1603 and Two LTC1391s as an 8-Channel Differential 16-Bit ADC System 5V 1 2 3 4 5 6 7 CH7 + 8 CH0 V+ CH1 CH2 D DOUT CH4 DIN CH5 CS CH6 CLK CH7 GND 16 VREF 2 3 4 5 6 7 CH7 – 8 V+ CH1 D CH2 V– CH3 DOUT CH4 DIN CH5 CS CH6 CLK CH7 GND AVDD 10 9 DVDD AVDD DGND SHDN 33 –5V 1µF + 13 4 REFCOMP 12 + 4.375V 47µF 11 7.5k 1.75X CONTROL LOGIC AND TIMING 2.