Datasheet

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1605fc

LTC1605

TYPICAL APPLICATIO

DESCRIPTIO

APPLICATIO S

FEATURES

16-Bit, 100ksps,

Sampling ADC

The LTC

1605 is a 100ksps, sampling 16-bit A/D con-

verter that draws only 55mW (typical) from a single 5V

supply. This easy-to-use device includes sample-and-

hold, precision reference, switched capacitor successive

approximation A/D and trimmed internal clock.

The LTC1605’s input range is an industry standard ±10V.

Maximum DC specs include ±2.0LSB INL and 16-bits no

missing codes over temperature. An external reference

can be used if greater accuracy over temperature is

needed.

The ADC has a microprocessor compatible, 16-bit or two

byte parallel output port. A convert start input and a data

ready signal (BUSY) ease connections to FIFOs, DSPs and

microprocessors.

■

Single 5V Supply

■

Bipolar Input Range:

10V

■

Power Dissipation: 55mW Typ

■

Guaranteed No Missing Codes

■

Sample Rate: 100ksps

■

Integral Nonlinearity: ±2.0LSB Max

■

Signal-to-Noise Ratio: 86dB Typ

■

Operates with Internal or External Reference

■

Internal Synchronized Clock

■

Improved 2nd Source to ADS7805 and AD976

■

28-Pin 0.3” PDIP, SSOP and SW Packages

■

Industrial Process Control

■

Multiplexed Data Acquisition Systems

■

High Speed Data Acquisition for PCs

■

Digital Signal Processing

Low Power, 100kHz, 16-Bit Sampling ADC on 5V Supply

20k20k200Ω

REFERENCE

4k 10k

16-BIT

SAMPLING ADC

D15 TO D0

33.2k

2.2µF

10µF

0.1µF

2.2µF

±10V

INPUT

CAP

REF

AGND1

AGND2

DGND

CONTROL

LOGIC AND

TIMING

BUSY

BYTE

R/C

28 27

6 TO 13

15 TO 22

DIGITAL

CONTROL

SIGNALS

1605 • TA01

16-BIT

OR 2 BYTE

PARALLEL

BUS

DIG

ANA

BUFFER

Typical INL Curve

CODE

INL (LSBs)

65535

1605 • TA02

16384

32768

49152

2.0

1.5

1.0

0.5

–0.5

–1.0

–1.5

–2.0

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

All other trademarks are the property of their respective owners.

Summary of content (16 pages)

PAGE 1
LTC1605 16-Bit, 100ksps, Sampling ADC U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO The LTC ®1605 is a 100ksps, sampling 16-bit A/D converter that draws only 55mW (typical) from a single 5V supply. This easy-to-use device includes sample-andhold, precision reference, switched capacitor successive approximation A/D and trimmed internal clock. Single 5V Supply Bipolar Input Range: ±10V Power Dissipation: 55mW Typ Guaranteed No Missing Codes Sample Rate: 100ksps Integral Nonlinearity: ±2.
PAGE 2
LTC1605 U U RATI GS W W W W AXI U U ABSOLUTE PACKAGE/ORDER I FOR ATIO (Notes 1, 2) TOP VIEW VANA .......................................................................... 7V VDIG to VANA ........................................................... 0.3V VDIG ........................................................................... 7V Ground Voltage Difference DGND, AGND1 and AGND2 .............................. ±0.3V Analog Inputs (Note 3) VIN ..................................................
PAGE 3
LTC1605 U U ANALOG INPUT The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 5) SYMBOL PARAMETER CONDITIONS VIN CIN Analog Input Range (Note 9) Analog Input Capacitance 4.75V ≤ VANA ≤ 5.25V, 4.75V ≤ VDIG ≤ 5.
PAGE 4
LTC1605 U U DIGITAL INPUTS AND DIGITAL OUTPUTS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 5) MIN LTC1605/LTC1605A TYP MAX SYMBOL PARAMETER CONDITIONS VOL Low Level Output Voltage VDD = 4.
PAGE 5
LTC1605 ELECTRICAL CHARACTERISTICS Note 8: Bipolar offset is the offset voltage measured from – 0.5 LSB when the output code flickers between 0000 0000 0000 0000 and 1111 1111 1111 1111. Note 9: Guaranteed by design, not subject to test. Note 10: Recommended operating conditions. Note 11: With CS low the falling R/C edge starts a conversion. If R/C returns high at a critical point during the conversion it can create small errors.
PAGE 6
LTC1605 U W TYPICAL PERFORMANCE CHARACTERISTICS MAGNITUDE (dB) LTC1605 Nonaveraged 4096 Point FFT Plot 0 –10 –20 –30 –40 –50 –60 –70 –80 –90 –100 –110 –120 –130 fSAMPLE = 100kHz fIN = 1kHz SINAD = 87.5dB THD = –101.
PAGE 7
LTC1605 U U U PIN FUNCTIONS on Pin 15 and bit 8 is output on Pin 22. Bit 7 is output on Pin 6 and the LSB is output on Pin 13. R/C (Pin 24): Read/Convert Input. With CS low, a falling edge on R/C puts the internal sample-and-hold into the hold state and starts a conversion. With CS low, a rising edge on R/C enables the output data bits. CS (Pin 25): Chip Select. Internally OR’d with R/C. With R/C low, a falling edge on CS will initiate a conversion.
PAGE 8
LTC1605 U U W U APPLICATIONS INFORMATION Conversion Details Driving the Analog Inputs The LTC1605 uses a successive approximation algorithm and an internal sample-and-hold circuit to convert an analog signal to a 16-bit or two byte parallel output. The ADC is complete with 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.
PAGE 9
LTC1605 U U W U APPLICATIONS INFORMATION The LTC1605 has an on-chip, temperature compensated, curvature corrected, bandgap reference, which is factory trimmed to 2.50V. The full-scale range of the ADC is equal to (±4 • VREF) or nominally ±10V. The output of the reference is connected to the input of a unity-gain buffer through a 4k resistor (see Figure 3). The input to the buffer or the output of the reference is available at REF (Pin 3).
PAGE 10
LTC1605 U U W U APPLICATIONS INFORMATION signal is applied to the input of the ADC and the resulting output codes are collected over a large number of conversions. For example in Figure 7 the distribution of output code is shown for a DC input that has been digitized 10000 times. The distribution is Gaussian and the RMS code transition is about 1LSB. 4500 4000 3500 COUNT 3000 2500 2000 1500 1000 500 0 –5 –4 –3 –2 –1 0 1 CODE 2 3 4 5 1605 • F07 Figure 7.
PAGE 11
LTC1605 U U W U APPLICATIONS INFORMATION t 10 t 10 t 10 t 10 R/C t1 t1 CS t3 t4 BUSY t6 MODE ACQUIRE CONVERT ACQUIRE t CONV HI-Z DATA BUS DATA VALID t 12 t7 HI-Z 1605 • F09 Figure 9. Using CS to Control Conversion and Read Timing t 10 t 10 R/C CS BYTE HI-Z PINS 6 TO 13 HIGH BYTE t 12 t 12 HI-Z PINS 15 TO 22 HI-Z LOW BYTE t7 LOW BYTE HI-Z HIGH BYTE 1605 • F03 MAGNITUDE (dB) Figure 10.
PAGE 12
LTC1605 U W U U APPLICATIONS INFORMATION a read. Again it is recommended that both R/C and CS return high within 3µs after the start of the conversion. Output Data The output data can be read as a 16-bit word or it can be read as two 8-bit bytes. The format of the output data is two’s complement. The digital input pin BYTE is used to control the two byte read. With the BYTE pin low the first eight MSBs are output on the D15 to D8 pins and the eight LSBs are output on the D7 to D0 pins.
PAGE 13
LTC1605 U W U U APPLICATIONS INFORMATION Figure 12. Component Side Silkscreen for the Suggested LTC1605 Evaluation Circuit ANALOG GROUND PLANE DIGITAL GROUND PLANE Figure 13. Bottom Side Showing Analog Ground Plane ANALOG GROUND PLANE Figure 14.
PAGE 14
2 1 2 1 2 R17 51 GND NA OUT U8 1MHz, OSC EXT_CLK 1 J1 J2 AIN GND E2 3 3 4 3 2 1 2 3 4 5 6 7 10 9 1 8 CLK LOAD ENP ENT A B C TRIM OUT QA QB QC QD RCO 14 13 12 11 15 5 6 7 8 JP1 R18 200Ω 1% VCC R21, 2k 3 15 2 1 JP4 2 CLK 13 CS VCC 3 VCC Q Q JP5 2 C3 0.1µF C4 2.2µF C16 1000pF C9 0.1µF C8 0.1µF C7 10µF VKK C5 0.1µF R19 33.2k 1% C10 0.
PAGE 15
LTC1605 U PACKAGE DESCRIPTION G Package 28-Lead Plastic SSOP (5.3mm) (Reference LTC DWG # 05-08-1640) 9.90 – 10.50* (.390 – .413) 28 27 26 25 24 23 22 21 20 19 18 17 16 15 1.25 ±0.12 7.8 – 8.2 5.3 – 5.7 0.42 ±0.03 7.40 – 8.20 (.291 – .323) 0.65 BSC 1 2 3 4 5 6 7 8 9 10 11 12 13 14 RECOMMENDED SOLDER PAD LAYOUT 5.00 – 5.60** (.197 – .221) 2.0 (.079) 0° – 8° 0.09 – 0.25 (.0035 – .010) 0.65 (.0256) BSC 0.55 – 0.95 (.022 – .037) NOTE: 1. CONTROLLING DIMENSION: MILLIMETERS MILLIMETERS 2.
PAGE 16
LTC1605 U PACKAGE DESCRIPTION SW Package 28-Lead Plastic Small Outline (Wide 0.300 Inch) (Reference LTC DWG # 05-08-1620) .050 BSC .045 ±.005 .030 ±.005 TYP .697 – .712 (17.70 – 18.08) NOTE 4 N 28 26 25 24 23 22 21 20 19 18 17 16 15 N .325 ±.005 .420 MIN 27 .394 – .419 (10.007 – 10.643) NOTE 3 1 2 3 N/2 N/2 RECOMMENDED SOLDER PAD LAYOUT .005 (0.127) RAD MIN .009 – .013 (0.229 – 0.330) .291 – .299 (7.391 – 7.595) NOTE 4 .010 – .029 × 45° (0.254 – 0.