Document
LTC1279 12-Bit, 600ksps Sampling A/D Converter with Shutdown
FEATURES
s s s s s s s s s s
DESCRIPTIO
s
Single Supply 5V or ± 5V Operation Sample Rate: 600ksps 70dB S/(N + D) and 74dB THD at Nyquist Power Dissipation: 60mW Typ Power Shutdown with Instant Wake-Up Internal Reference Can Be Overdriven Externally Internal Synchronized Clock; No Clock Required High Impedance Analog Input Input Range: 0V to 5V or ± 2.5V New Flexible, Friendly Parallel Interface Eases Connections to DSPs and FIFOs 24-Pin SO Wide Package
The LTC®1279 is a 1.4µs, 600ksps, sampling 12-bit A/D converter which draws only 60mW from a single 5V or ± 5V supplies. This easy-to-use device comes complete with a 160ns sample-and-hold, a precision reference and an internally trimmed clock. Unipolar and bipolar conversion modes add to the flexibility of the ADC. The low power dissipation is reduced even more, drawing only 8.5mW in power shutdown mode. Instant wake-up from power shutdown allows the converter to be powered down even during brief inactive periods. The LTC1279 converts 0V to 5V unipolar inputs from a single 5V supply and ± 2.5V bipolar inputs from ± 5V supplies. Maximum DC specs include ± 1LSB INL and ± 1LSB DNL. Outstanding guaranteed AC performance includes 70dB S/(N + D) and 78dB THD at the input frequency of 100kHz over temperature. The internal clock is trimmed for 1.4µs conversion time. The clock automatically synchronizes to each sample command, eliminating problems with asynchronous clock noise found in competitive devices. A separate conversion start input and a data-ready signal (BUSY) ease connections to FIFOs, DSPs and microprocessors.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATI
s s s s s
S
High Speed Data Acquisition Digital Signal Processing Multiplexed Data Acquisition Systems Audio and Telecom Processing Spectrum Analysis
TYPICAL APPLICATI
Single 5V Supply, 600kHz, 12-Bit Sampling A/D Converter
LTC1279 ANALOG INPUT 1 A AVDD (0V TO 5V) 2 IN VREF VSS 3 AGND BUSY 0.1µF 4 D11(MSB) CS 5 D10 RD 6 D9 CONVST 7 D8 SHDN 8 D7 DVDD 9 12-BIT D6 D0 PARALLEL 10 D5 D1 BUS 11 D4 D2 12 DGND D3 5V 24 23 22 21 20 19 18 17 16 15 14 13 10µF
Effective Bits and Signal-to-(Noise + Distortion) vs Input Frequency
12 11
0.1µF
10µF
EFFECTIVE NUMBER OF BITS
2.42V REFERENCE OUTPUT
+
+
10 9 8 7 6 5 4 3 2 1 0 10k
µP CONTROL LINES CONVERSION-START INPUT POWER SHUTDOWN INPUT
LTC1279 • TA01
U
74 68 NYQUIST FREQUENCY 62 56 50
SIGNAL/(NOISE + DISTORTION) (dB)
UO
UO
fSAMPLE = 600kHz 100k 1M FREQUENCY (Hz) 5M
1279 G03
1
LTC1279 ABSOLUTE AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW AIN VREF AGND D11(MSB) D10 D9 D8 D7 D6 1 2 3 4 5 6 7 8 9 24 AVDD 23 VSS 22 BUSY 21 CS 20 RD 19 CONVST 18 SHDN 17 DVDD 16 D0 15 D1 14 D2 13 D3
AVDD = DVDD = VDD (Notes 1, 2)
Supply Voltage (VDD) ................................................ 7V Negative Supply Voltage (VSS) Bipolar Operation Only ......................... – 6V to GND Total Supply Vo.