Linear Technology LTC1272-8CCN, LTC1272-8ACS, LTC1272-3CCS, LTC1272-3CCN, LTC1272-3ACS Datasheet

...

0 (0)

FEATURES

■AD7572 Pinout

■12-Bit Resolution

■3μs and 8μs Conversion Times

■On-Chip Sample-and-Hold

■Up to 250kHz Sample Rates

■5V Single Supply Operation

■No Negative Supply Required

■On-Chip 25ppm/°C Reference

■75mW (Typ) Power Consumption

■24-Pin Narrow DIP and SOL Packages

■ESD Protected on All Pins

APPLICATIOUS

■High Speed Data Acquisition

■Digital Signal Processing (DSP)

■Multiplexed Data Acquisition Systems

■Single Supply Systems

LTC1272

12-Bit, 3μs, 250kHz Sampling A/D Converter

DESCRIPTIOU

The LTC1272 is a 3μs, 12-bit, successive approximation sampling A/D converter. It has the same pinout as the industry standard AD7572 and offers faster conversion time, on-chip sample-and-hold, and single supply operation. It uses LTBiCMOSTM switched-capacitor technology to combine a high speed 12-bit ADC with a fast, accurate sample-and-hold and a precision reference.

The LTC1272 operates with a single 5V supply but can also accept the 5V/–15V supplies required by the AD7572 (Pin

23, the negative supply pin of the AD7572, is not connected on the LTC1272). The LTC1272 has the same 0V to 5V input range as the AD7572 but, to achieve single supply operation, it provides a 2.42V reference output instead of the

– 5.25V of the AD7572. It plugs in for the AD7572 if the reference capacitor polarity is reversed and a 1μs sample- and-hold acquisition time is allowed between conversions.

The output data can be read as a 12-bit word or as two 8-bit bytes. This allows easy interface to both 8-bit and higher processors. The LTC1272 can be used with a crystal or an external clock and comes in speed grades of 3μs and 8μs.

LTBiCMOS is a trademark of Linear Technology Corporation

TYPICAL APPLICATIOU

Single 5V Supply, 3μs, 12-Bit Sampling ADC

1024 Point FFT, fS = 250kHz, fIN = 10kHz

LTC1272

ANALOG INPUT

A IN

VDD

2.42V

(0V TO 5V)

–20

VREF

= 72.1

VREF

(N+D)

OUTPUT

10μF

0.1

0.1μF

AGND

BUSY

(dB)

–40

D11 (MSB)

μP

–60

AMPLITUDE

D10

CONTROL

HBEN

LINES

–80

CLK OUT

–100

CLK IN

8 OR 12-BIT

D0/8

–120

PARALLEL

D1/9

–140

BUS

100

120

D2/10

FREQUENCY (kHz)

DGND

D3/11

LTC1272 • TA02

LTC1272 • TA01

LTC1272

ABSOLUTE WAXIWUW RATIUGS

(Notes 1 and 2)

Supply Voltage (VDD) .................................................	6V
Analog Input Voltage (Note 3) ...................	– 0.3V to 15V
Digital Input Voltage ..................................	– 0.3V to 12V
Digital Output Voltage ....................	– 0.3V to VDD + 0.3V
Power Dissipation ..............................................	500mW

Operating Temperature Range	0°C to 70°C
LTC1272-XAC, CC .................................	0°C to 70°C
Storage Temperature Range .................	– 65°C to 150°C
Lead Temperature (Soldering, 10 sec)..................	300°C

PACKAGE/ORDER IUFORWATIOU

		TOP VIEW						TOP VIEW
A IN				VDD
A IN	1		24	VDD	A IN	1			24	VDD
				NC
VREF	2		23	NC	VREF	2			23	NC

AGND	3		22	BUSY	AGND	3			22	BUSY

(MSB) D11	4		21	CS	(MSB) D11	4			21	CS

D10	5		20	RD	D10	5			20	RD

D9	6		19	HBEN	D9	6			19	HBEN

D8	7		18	CLK OUT	D8	7			18	CLK OUT
D7				CLK IN
D7	8		17	CLK IN	D7	8			17	CLK IN

D6	9		16	D0/8	D6	9			16	D0/8

D5	10		15	D1/9	D5	10			15	D1/9

D4	11		14	D2/10	D4	11			14	D2/10
DGND				D3/11
DGND	12		13	D3/11	DGND	12			13	D3/11

		N PACKAGE						S PACKAGE
	24-LEAD PLASTIC DIP						24-LEAD PLASTIC SOL
TJMAX = 110°C, θJA = 100°C/W						TJMAX = 110°C, θJA = 130°C/W

ORDER PART NUMBER

CONVERSION	CONVERSION
TIME = 3μs	TIME = 8μs

LTC1272-3ACN	LTC1272-8ACN
LTC1272-3CCN	LTC1272-8CCN

S PACKAGE ONLY

LTC1272-3ACS LTC1272-8ACS LTC1272-3CCS LTC1272-8CCS

Consult factory for Industrial and Military grade parts.

COUVERTER CHARACTERISTICS		With Internal Reference (Note 4)
					LTC1272-XA			LTC1272-XC
PARAMETER	CONDITIONS			MIN	TYP	MAX	MIN	TYP	MAX	UNITS
Resolution (No Missing Codes)			●	12			12			Bits

Integral Linearity Error	(Note 5)		●			±1/2			±1	LSB

Differential Linearity Error			●			±1			±1	LSB

Offset Error						±3			±4	LSB
			●			±4			±6	LSB

Gain Error						±10			±15	LSB

Full-Scale Tempco	IOUT (Reference) = 0		●		±5	±25		±10	±45	ppm/°C

LTC1272

IUTERUAL REFEREUCE CHARACTERISTICS (Note 4)
				LTC1272-XA			LTC1272-XC
PARAMETER	CONDITIONS		MIN	TYP	MAX	MIN	TYP	MAX	UNITS

VREF Output Voltage (Note 6)	IOUT = 0		2.400	2.420	2.440	2.400	2.420	2.440	V
VREF Output Tempco	IOUT = 0	●		5	25		10	45	ppm/°C
VREF Line Regulation	4.75V £ VDD £ 5.25V, IOUT = 0			0.01			0.01		LSB/V
VREF Load Regulation (Sourcing Current)	0 £ êIOUT ê £ 1mA			2			2		LSB/mA

DIGITAL AUD DC ELECTRICAL CHARACTERISTICS

(Note 4)

LTC1272-XA/C

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

VIH

High Level Input Voltage

CS,

RD,

HBEN, CLK IN

VDD = 5.25V

●

2.4

VIL

Low Level Input Voltage

VDD = 4.75V

0.8

CS,

RD, HBEN, CLK IN

●

IIN

Input Current

HBEN

VIN = 0V to VDD

±10

CS,

RD,

●

Input Current CLK IN

VIN = 0V to VDD

●

±20

VOH

High Level Output Voltage All Logic Outputs

VDD = 4.75V IOUT = – 10mA

4.7

IOUT = – 200mA

●

4.0

VOL

Low Level Output Voltage All Logic Outputs

VDD = 4.75V, IOUT = 1.6mA

●

0.4

IOZ

High-Z Output Leakage D11-D0/8

VOUT = 0V to VDD

●

±10

COZ

High-Z Output Capacitance (Note 7)

●

ISOURCE

Output Source Current

VOUT = 0V

– 10

ISINK

Output Sink Current

VOUT = VDD

IDD

Positive Supply Current

= VDD, AIN = 5V

●

Power Dissipation

DYUAWIC ACCURACY (Note 4) fSAMPLE = 250kHz (LTC1272-3), 111kHz (LTC1272-8)

LTC1272-XA/C

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

S/(N + D)

Signal-to-Noise Plus Distortion Ratio

10kHz Input Signal

THD

Total Harmonic Distortion (Up to 5th Harmonic)

10kHz Input Signal

– 82

Peak Harmonic or Spurious Noise

10kHz Input Signal

– 82

AUALOG I

PUT

(Note 4)

					LTC1272-XA/B/C
SYMBOL	PARAMETER	CONDITIONS		MIN	TYP	MAX	UNITS

VIN	Input Voltage Range	4.75V £ VDD £ 5.25V	●	0		5	V
IIN	Input Current		●			3.5	mA
CIN	Input Capacitance				50		pF
tACQ	Sample-and-Hold Acquisition Time		●		0.45	1	ms

LTC1272

TIWIUG CHARACTERISTICS

(Note 8)

LTC1272-XA/C

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Setup Time

●

Delay

CL = 50pF

190

BUSY

COM Grade

●

230

Data Access Time After

↓

CL = 20pF

COM Grade

●

110

CL = 100pF

125

COM Grade

●

150

Pulse Width

COM Grade

●

Hold Time

●

Data Setup Time After

BUSY

COM Grade

●

Bus Relinquish Time

COM Grade

●

HBEN to

Setup Time

●

HBEN to

Hold Time

●

t10

Delay Between

Operations

200

●

t11

Delay Between Conversions

μs

t12

Aperture Delay of Sample and Hold

Jitter <50ps

t13

CLK to

Delay

170

BUSY

COM Grade

●

220

tCONV

Conversion Time

●

CLK

CYCLES

The ● indicates specifications which apply over the full operating temperature range; all other limits and typicals TA = 25°C.

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 and AGND wired together, unless otherwise noted.

Note 3: When the analog input voltage is taken below ground it will be clamped by an internal diode. This product can handle, with no external diode, input currents of greater than 60mA below ground without latch-up.

Note 4: VDD = 5V, fCLK = 4MHz for LTC1272-3, and 1.6MHz for LTC1272-8, tr = tf = 5ns unless otherwise specified. For best analog

performance, the LTC1272 clock should be synchronized to the RD and CS control inputs with at least 40ns separating convert start from the nearest clock edge.

Note 5: Linearity error is specified between the actual end points of the A/D transfer curve.

Note 6: The LTC1272 has the same 0V to 5V input range as the AD7572 but, to achieve single supply operation, it provides a 2.42V reference output instead of the –5.25V of the AD7572. This requires that the polarity of the reference bypass capacitor be reversed when plugging an LTC1272 into an AD7572 socket.

Note 7: Guaranteed by design, not subject to test.

Note 8: VDD = 5V. Timing specifications are sample tested at 25°C to ensure compliance. All input control signals are specified with tr = tf = 5ns (10% to 90% of 5V) and timed from a voltage level of 1.6V. See Figures 13 through 17.

LTC1272

PIU FUUCTIOUS

AIN (Pin 1): Analog Input, 0V to 5V Unipolar Input.

VREF (Pin 2): 2.42V Reference Output. When plugging into an AD7572 socket, reverse the reference bypass capacitor polarity and short the 10Ω series resistor.

AGND (Pin 3): Analog Ground.

D11 to D4 (Pins 4-11): Three-State Data Outputs.

DGND (Pin 12): Digital Ground.

D3/11 to D0/8 (Pins 13-16): Three-State Data Outputs.

CLK IN (Pin 17): Clock Input. An external TTL/CMOS compatible clock may be applied to this pin or a crystal can be connected between CLK IN and CLK OUT.

CLK OUT (Pin 18): Clock Output. An inverted CLK IN signal appears at this pin.

Data Bus Output, CS and RD = LOW

HBEN (Pin 19): High Byte Enable Input. This pin is used to multiplex the internal 12-bit conversion result into the lower bit outputs (D7 to D0/8). See table below. HBEN also disables conversion starts when HIGH.

RD (Pin 20): Read Input. This active low signal starts a conversion when CS and HBEN are low. RD also enables the output drivers when CS is low.

CS (Pin 21): The Chip Select Input must be low for the ADC to recognize RD and HBEN inputs.

BUSY (Pin 22): The BUSY Output is low when a conversion is in progress.

NC (Pin 23): Not Connected Internally. The LTC1272 does not require negative supply. This pin can accommodate the –15V required by the AD7572 without problems.

VDD (Pin 24): Positive Supply, 5V.

Pin 4

Pin 5

Pin 6

Pin 7

Pin 8

Pin 9

Pin 10

Pin 11

Pin 13

Pin 14

Pin 15

Pin 16

MNEMONIC*

D11

D10

D3/11

D2/10

D1/9

D0/8

HBEN = LOW

DB11

DB10

DB9

DB8

DB7

DB6

DB5

DB4

DB3

DB2

DB1

DB0

HBEN = HIGH

DB11

DB10

DB9

DB8

LOW

DB11

DB10

DB9

DB8

*D11...D0/8 are the ADC data output pins.

DB11...DB0 are the 12-bit conversion results, DB11 is the MSB.

TYPICAL PERFORWAUCE CHARACTERISTICS

Integral Nonlinearity

INL ERROR (LSBs)

1.0

VDD = 5V fCLK = 4MHz

0.5

–0.5

–1.0

512

1024

1536

2048

2560

3072

3584

4096

CODE

LTC1272 • TPC01

LTC1272

TYPICAL PERFORWAUCE CHARACTERISTICS

INL ERROR (LSBs)

Differential Nonlinearity

1.0

VDD = 5V

fCLK = 4MHz

0.5

–0.5

–1.0

512

1024

1536

2048

2560

3072

3584

4096

CODE

LTC1272 • TPC02

VDD SUPPLY CURRENT, IDD (mA)

VDD Supply Current vs

Temperature

VDD = 5V 25 fCLK = 4MHz

0	–25	0	25	50	75	100	125
–55

TEMPERATURE (°C)

LT1272 • TPC03

Minimum Clock Frequency vs

Temperature

	600
	600
		VDD = 5V
(kHz)	500


	400

FREQUENCY
FREQUENCY	300
CLOCK	300
CLOCK	200
	200
	100
	100
	0
	0	–25	0	25	50	75	100	125
	–55	–25	0	25	50	75	100	125

TEMPERATURE (°C)

LT1272 • TPC04

CLOCK FREQUENCY (MHz)

Maximum Clock Frequency vs Temperature

2	–25	0	25	50	75	100	125
–55

TEMPERATURE (°C)

LT1272 • TPC05

	VREF vs ILOAD (mA)
	2.435
	2.430
	2.425
(V)	2.420							ENOBs*
V	2.420							ENOBs*
REF
	2.415
	2.410
	2.405	–4	–3	–2	–1	0	1	2
	–5	–4	–3	–2	–1	0	1	2
				IL (mA)			LT1272 • TPC06
							LT1272 • TPC06

LTC1272 ENOBs* vs Frequency

fS = 250kHz 1 VDD = 5V

100

120

fIN (kHz)

LT1272 • TPC07

*EFFECTIVE NUMBER OF BITS, ENOBs = S/(N + D) – 1.76dB 6.02

+ 14 hidden pages