Datasheet

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LTC1197/LTC1197L

LTC1199/LTC1199L

10-Bit, 500ksps ADCs in

MSOP with Auto Shutdown

Single 2.7V Supply, 250ksps, 10-Bit Sampling ADC

Supply Current vs Sampling Frequency

SAMPLING FREQUENCY (kHz)

0.01

SUPPLY CURRENT (µA)

100

1000

10000

100

1197/99 G03

0.1

1000

= 5V

CLK

= 7.2MHz

= 2.7V

CLK

= 3.5MHz

+IN

–IN

GND

CLK

OUT

REF

LTC1197L

1197/99 TA01

ANALOG INPUT

0V TO 2.7V RANGE

2.7V

1µF

SERIAL DATA LINK TO

ASIC, PLD, MPU, DSP

OR SHIFT REGISTERS

The LTC

1197/LTC1197L/LTC1199/LTC1199L are

10-bit A/D converters with sampling rates up to 500kHz.

They have 2.7V (L) and 5V versions and are offered in

8-pin MSOP and SO packages. Power dissipation is typi-

cally only 2.2mW at 2.7V (25mW at 5V) during full speed

operation. The automatic power down reduces supply

current linearly as sample rate is reduced. These 10-bit,

switched-capacitor, successive approximation ADCs in-

clude a sample-and-hold. The LTC1197/LTC1197L have a

differential analog input with an adjustable reference pin.

The LTC1199/LTC1199L offer a software-selectable

2-channel MUX.

The 3-wire serial I/O, MSOP and SO-8 packages, 2.7V

operation and extremely high sample rate-to-power ratio

make these ADCs ideal choices for compact, low power

high speed systems.

These circuits can be used in ratiometric applications or

with external references. The high impedance analog

inputs and the ability to operate with reduced spans below

1V full scale (LTC1197/LTC1197L) allow direct connec-

tion to signal sources in many applications, eliminating

the need for gain stages.

■

8-Pin MSOP and SO Packages

■

10-Bit Resolution at 500ksps

■

Single Supply: 5V or 3V

■

Low Power at Full Speed:

25mW Typ at 5V

2.2mW Typ at 2.7V

■

Auto Shutdown Reduces Power Linearly

at Lower Sample Rates

■

10-Bit Upgrade to 8-Bit LTC1196/LTC1198

■

SPI and MICROWIRE

Compatible Serial I/O

■

Low Cost

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

MICROWIRE is a trademark of National Semiconductor Corporation.

■

High Speed Data Acquisition

■

Portable or Compact Instrumentation

■

Low Power or Battery-Operated Instrumentation

FEATURES

DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO

Summary of content (28 pages)

PAGE 1
LTC1197/LTC1197L LTC1199/LTC1199L 10-Bit, 500ksps ADCs in MSOP with Auto Shutdown U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO 8-Pin MSOP and SO Packages 10-Bit Resolution at 500ksps Single Supply: 5V or 3V Low Power at Full Speed: 25mW Typ at 5V 2.2mW Typ at 2.
PAGE 2
LTC1197/LTC1197L LTC1199/LTC1199L W W W AXI U U ABSOLUTE RATI GS (Notes 1, 2) Supply Voltage (VCC) ............................................... 12V Voltage Analog Input ..................... GND – 0.3V to VCC + 0.3V Digital Input ................................ GND – 0.3V to 12V Digital Output .................... GND – 0.3V to VCC + 0.3V Power Dissipation .............................................. 500mW Storage Temperature Range .................
PAGE 3
LTC1197/LTC1197L LTC1199/LTC1199L U U U U WW RECO E DED OPERATI G CO DITIO S The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C.
PAGE 4
LTC1197/LTC1197L LTC1199/LTC1199L W U U CO VERTER A D ULTIPLEXER CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 2.7V, VREF = 2.5V (LTC1197L), fCLK = fCLK(MAX) as defined in Recommended Operating Conditions, unless otherwise noted.
PAGE 5
LTC1197/LTC1197L LTC1199/LTC1199L U DIGITAL AND DC ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, VREF = 5V, unless otherwise noted. MIN LTC1197 TYP MAX CONDITIONS VIH High Level Input Voltage VCC = 5.25V ● VIL Low Level Input Voltage VCC = 4.75V ● IIH High Level Input Current VIN = VCC ● IIL Low Level Input Current VIN = 0V ● VOH High Level Output Voltage VCC = 4.
PAGE 6
LTC1197/LTC1197L LTC1199/LTC1199L AC CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, VREF = 5V, fCLK = fCLK(MAX) as defined in Recommended Operating Conditions, unless otherwise noted.
PAGE 7
LTC1197/LTC1197L LTC1199/LTC1199L U W TYPICAL PERFOR A CE CHARACTERISTICS Supply Current vs Clock Rate* 14 70 SUPPLY CURRENT (mA) 14 12 10 8 6 VCC = 5V 4 2 VCC = 2.7V 100 1000 FREQUENCY (kHz) 60 ACTIVE MODE 10 10000 50 8 40 6 30 4 20 SHUTDOWN MODE 2 0 10 12 0 0 1 2 3 5 6 7 4 SUPPLY VOLTAGE (V) 1197/99 G01 SHUTDOWN CURRENT (nA) SUPPLY CURRENT (mA) fCLK = 3.5MHz TA = 25°C VCC = 9V 16 10000 80 16 1000 SUPPLY CURRENT (µA) 20 18 VCC = 5V fCLK = 7.2MHz 100 10 VCC = 2.
PAGE 8
LTC1197/LTC1197L LTC1199/LTC1199L U W TYPICAL PERFOR A CE CHARACTERISTICS LTC1197L Change in Linearity vs Supply Voltage 2.0 VREF = 2.5V fCLK = 3.5MHz 0.8 1.5 CHANGE IN OFFSET (LSBs) 0.6 0.4 0.2 0 – 0.2 – 0.4 – 0.6 0.5 0 – 0.5 –1.0 –1.5 – 1.0 – 2.0 1 3 4 2 SUPPLY VOLTAGE (V) 5 3 4 2 SUPPLY VOLTAGE (V) 0 – 0.2 – 0.4 – 0.6 9 0 – 0.5 –1.0 0.5 0 – 0.5 –1.0 – 2.0 – 2.0 0 1 2 3 4 5 6 7 SUPPLY VOLTAGE (V) 8 0 9 7 3 5 6 4 SUPPLY VOLTAGE (V) 9 2.0 VCC = 5V fCLK = 7.2MHz TA = 25°C 2.
PAGE 9
LTC1197/LTC1197L LTC1199/LTC1199L U W TYPICAL PERFOR A CE CHARACTERISTICS Linearity vs Temperature 0 0 VCC = 5V VREF = 5V fCLK = 7.2MHz VCC = 5V VREF = 5V fCLK = 7.2MHz – 0.1 – 0.2 0.3 0.2 – 0.3 – 0.4 – 0.4 – 0.5 – 0.6 – 0.7 – 0.6 – 0.8 – 1.0 – 0.8 0.1 – 1.2 – 0.9 0 –55 – 30 –5 45 70 20 TEMPERATURE (°C) 95 – 1.
PAGE 10
LTC1197/LTC1197L LTC1199/LTC1199L U U U PI FU CTIO S CS (Pin 1): Chip Select Input. A logic low on this input enables the LTC1197/LTC1197L/LTC1199/LTC1199L. Power shutdown is activated when CS is brought high. + IN, CH0 (Pin 2): Analog Input. This input must be free of noise with respect to GND. – IN, CH1 (Pin 3): Analog Input. This input must be free of noise with respect to GND. GND (Pin 4): Analog Ground. GND should be tied directly to an analog ground plane.
PAGE 11
LTC1197/LTC1197L LTC1199/LTC1199L TEST CIRCUITS Voltage Waveforms for DOUT Rise and Fall Times, tr, tf Load Circuit for tdDO, tr, tf, tdis and ten TEST POINT VOH DOUT VOL VCC tdis WAVEFORM 2, ten 3k DOUT tr tdis WAVEFORM 1 20pF tf 1197/99 TC04 1197/99 TC01 Voltage Waveforms for DOUT Delay Time, tdDO Voltage Waveforms for tdis VIH CLK VIH CS tdDO thDO VOH DOUT DOUT WAVEFORM 1 (SEE NOTE 1) 90% tdis VOL 1197/99 TC02 DOUT WAVEFORM 2 (SEE NOTE 2) 10% NOTE 1: WAVEFORM 1 IS FOR AN OUTPUT W
PAGE 12
LTC1197/LTC1197L LTC1199/LTC1199L U W U U APPLICATIO S I FOR ATIO OVERVIEW SERIAL INTERFACE The LTC1197/LTC1197L/LTC1199/LTC1199L are 10-bit switched-capacitor A/D converters. These sampling ADCs typically draw 5mA of supply current when sampling up to 500kHz (800µA at 2.7V sampling up to 250kHz). Supply current drops linearly as the sample rate is reduced (see Supply Current vs Sample Rate in the Typical Performance Characteristics).
PAGE 13
LTC1197/LTC1197L LTC1199/LTC1199L U W U U APPLICATIO S I FOR ATIO tCYC (16 CLKs)* CS tsuCS CLK 1 2 3 4 5 6 7 8 9 10 12 13 14 15 16 1 ODD/ SIGN START DIN DON’T CARE SGL/ DIFF DOUT 11 DUMMY tdDO ten HI-Z NULL BITS Hi-Z B9 B8 B7 B6 B5 B4 B3 B2 B1 B0* tCONV (10.5 CLKs) tSMPL (1.5 CLKs) POWER DOWN *AFTER COMPLETING THE DATA TRANSFER, IF FURTHER CLOCKS ARE APPLIED WITH CS LOW, THE ADC WILL OUTPUT ZEROS INDEFINITELY 1197/99 F02 Figure 2.
PAGE 14
LTC1197/LTC1197L LTC1199/LTC1199L U W U U APPLICATIO S I FOR ATIO Dummy Bit Unipolar Transfer Curve The dummy bit is a placeholder that extends the acquisition time of the ADC. This bit can be either high or low and does not affect the conversion of the ADC. 1111111111 1111111110 • • • Operation with DIN and DOUT Tied Together 0000000001 0000000000 VIN VREF VREF – 1LSB VREF – 2LSB 1LSB 0V The LTC1199/LTC1199L can be operated with DIN and DOUT tied together.
PAGE 15
LTC1197/LTC1197L LTC1199/LTC1199L U W U U APPLICATIO S I FOR ATIO that convert continuously, the LTC1197/LTC1197L/ LTC1199/LTC1199L will draw their normal operating power continuously. Several things must be taken into account to achieve micropower operation. Shutdown Figures 1 and 2 show the operating sequence of the LTC1197/LTC1197L/LTC1199/LTC1199L. The converter draws power when the CS pin is low and powers itself down when that pin is high.
PAGE 16
LTC1197/LTC1197L LTC1199/LTC1199L U W U U APPLICATIO S I FOR ATIO Mixed Supplies SAMPLE-AND-HOLD It is possible to have a microprocessor running off a 5V supply and communicate with the ADC operating on 3V or 9V supplies.
PAGE 17
LTC1197/LTC1197L LTC1199/LTC1199L U W U U APPLICATIO S I FOR ATIO SAMPLE HOLD “+” INPUT MUST SETTLE DURING THIS TIME CS tSMPL tCONV CLK DIN START SGL/DIFF ODD/SGN DUMMY DON‘T CARE DOUT 1ST BIT TEST “–” INPUT MUST SETTLE DURING THIS TIME “+” INPUT “–” INPUT 1197/99 F05 Figure 5.
PAGE 18
LTC1197/LTC1197L LTC1199/LTC1199L U W U U APPLICATIO S I FOR ATIO conversion result. However, it is critical that the “–” input voltage settles completely during the first CLK cycle of the conversion time and be free of noise. Minimizing RSOURCE– and C2 will improve settling time (see Figure 6). If a large “–” input source resistance must be used, the time allowed for settling can be extended by using a slower CLK frequency. across the resistor.
PAGE 19
LTC1197/LTC1197L LTC1199/LTC1199L U W U U APPLICATIO S I FOR ATIO The effective resolution of the LTC1197/LTC1197L can be increased by reducing the input span of the converter. The LTC1197/LTC1197L exhibits good linearity and gain over a wide range of reference voltages (see typical curves of Linearity and Full-Scale Error vs Reference Voltage).
PAGE 20
LTC1197/LTC1197L LTC1199/LTC1199L U W U U APPLICATIO S I FOR ATIO Signal-to-Noise Ratio Effective Number of Bits The signal-to-noise ratio (SNR) 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. This includes distortion as well as noise products and for this reason it is sometimes referred to as signal-to-noise + distortion [S/(N + D)].
PAGE 21
LTC1197/LTC1197L LTC1199/LTC1199L U TYPICAL APPLICATIO S MICROPROCESSOR INTERFACES Motorola SPI (MC68HC05C4, MC68HC11) The LTC1197/LTC1197L/LTC1199/LTC1199L can interface directly (without external hardware to most popular microprocessor (MPU) synchronous serial formats (see Table 1). If an MPU without a dedicated serial port is used, then three or four of the MPU’s parallel port lines can be programmed to form the serial link.
PAGE 22
LTC1197/LTC1197L LTC1199/LTC1199L U TYPICAL APPLICATIO S Data Exchange Between LTC1199 and MC68HC05C4 START BIT BYTE 1 MPU TRANSMIT WORD SGL/ ODD/ DIFF SIGN 1 BYTE 2 (DUMMY) X X X X X X X DUMMY X X X X X X = DON‘T CARE CS START DUMMY SGL/ ODD/ DIFF SIGN DIN DON‘T CARE CLK DOUT B9 MPU RECEIVED WORD ? ? ? ? 0 0 B8 B9 B7 B6 B7 B8 B5 B6 1ST TRANSFER Hardware and Software Interface to Motorola MC68HC05C4 C0 CS CLK ANALOG INPUTS LTC1199 DIN DOUT 0 0 0 0 0 0 B9
PAGE 23
LTC1197/LTC1197L LTC1199/LTC1199L U TYPICAL APPLICATIO S Interfacing to the Parallel Port of the Intel 8051 Family LABEL The Intel 8051 has been chosen to demonstrate the interface between the LTC1199 and parallel port microprocessors. Normally, the CS, CLK and DIN signals would be generated on three port lines and the DOUT signal read on a fourth port line. This works very well.
PAGE 24
LTC1197/LTC1197L LTC1199/LTC1199L U TYPICAL APPLICATIO S A “Quick Look” Circuit for the LTC1197 Users can get a quick look at the function and timing of the LTC1197 by using the following simple circuit (Figure 11). VREF is tied to VCC. VIN is applied to the +IN input and the – IN input is tied to the ground. CS is driven at 1/16 the clock rate by the 74HC161 and DOUT outputs the data.
PAGE 25
LTC1197/LTC1197L LTC1199/LTC1199L U TYPICAL APPLICATIO S Resistive Touchscreen Interface Figure 13 shows the LTC1199 in a 4-wire resistive touchscreen application. Transistor pairs Q1-Q3, Q2-Q4 apply 5V and ground to the X axis and Y axis, respectively. The LTC1199, with its 2-channel multiplexer, digitizes the voltage generated by each axis and transmits the conversion results to the system’s processor through a serial interface.
PAGE 26
LTC1197/LTC1197L LTC1199/LTC1199L U TYPICAL APPLICATIO S Battery Current Monitor The LTC1197L/LTC1199L are ideal for 3V systems. Figure 14 shows a 2.7V to 4V battery current monitor that draws only 45µA at 3V from the battery it monitors, sampling at a 1Hz rate. To minimize supply current, the microprocessor uses the LTC1152 SHDN pin to turn on the op amp prior to making a measurement and then turn it off after the measurement has been made. The battery current is sensed with the 0.
PAGE 27
LTC1197/LTC1197L LTC1199/LTC1199L U PACKAGE DESCRIPTIO Dimensions in inches (millimeters), unless otherwise noted. MS8 Package 8-Lead Plastic MSOP (LTC DWG # 05-08-1660) 0.118 ± 0.004* (3.00 ± 0.102) 8 7 6 5 0.118 ± 0.004** (3.00 ± 0.102) 0.193 ± 0.006 (4.90 ± 0.15) 1 2 3 4 0.043 (1.10) MAX 0.007 (0.18) 0.034 (0.86) REF 0° – 6° TYP 0.021 ± 0.006 (0.53 ± 0.015) SEATING PLANE 0.009 – 0.015 (0.22 – 0.38) 0.005 ± 0.002 (0.13 ± 0.05) 0.0256 (0.
PAGE 28
LTC1197/LTC1197L LTC1199/LTC1199L RELATED PARTS PART NUMBER SAMPLE RATE POWER DISSIPATION DESCRIPTION 8-Bit, Pin Compatible Serial Output ADCs LTC1096/LTC1096L 33kHz/15kHz 0.5mW* 1-Channel, Unipolar Operation with Reference Input, 5V/3V LTC1098/LTC1098L 33kHz/15kHz 0.