TEXAS INSTRUMENTS TLV571 Technical data
TLV571
2.7 V TO 5.5 V, 1-CHANNEL, 8-BIT,
PARALLEL ANALOG-TO-DIGITAL CONVERTER
SLAS239A – SEPTEMBER 1999 – REVISED FEBRUARY 2000
features
D
Fast Throughput Rate: 1.25 MSPS at 5 V,
625 KSPS at 3 V
D
Wide Analog Input: 0 V to AV
D
Differential Nonlinearity Error: < ± 0.5 LSB
D
Integral Nonlinearity Error: < ± 0.5 LSB
D
Single 2.7-V to 5.5-V Supply Operation
D
Low Power: 12 mW at 3 V and 35 mW at 5 V
D
Auto Power Down of 1 mA Max
D
Software Power Down: 10 µA Max
D
Internal OSC
D
Hardware Configurable
D
DSP and Microcontroller Compatible
DD
Parallel Interface
D
Binary/Twos Complement Output
D
Hardware Controlled Extended Sampling
D
Hardware or Software Start of Conversion
description
The TLV571 is an 8-bit data acquisition system
applications
D
Mass Storage and HDD
D
Automotive
D
Digital Servos
D
Process Control
D
General-Purpose DSP
D
Image Sensor Processing
DW OR PW PACKAGE
(TOP VIEW)
CS
WR
RD
CLK
DGND
DV
DD
INT/EOC
DGND
DGND
D0
D1
D2
NC – No internal connection
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
NC
AIN
AV
AGND
REFM
REFP
CSTART
A1/D7
A0/D6
D5
D4
D3
that combines a high-speed 8-bit ADC and a
parallel interface. The device contains two on-chip control registers allowing control of software conversion start
and power down via the bidirectional parallel port. The control registers can be set to a default mode using a
dummy RD
while WR is tied low allowing the registers to be hardware configurable.
DD
The TL V571 operates from a single 2.7-V to 5.5-V power supply. It accepts an analog input range from 0 V to
AVDD and digitizes the input at a maximum 1.25 MSPS throughput rate at 5 V . The power dissipations are only
12 mW with a 3-V supply or 35 mW with a 5-V supply. The device features an auto power-down mode that
automatically powers down to 1 mA 50 ns after conversion is performed. In software power-down mode, the
ADC is further powered down to only 10 µA.
Very high throughput rate, simple parallel interface, and low power consumption make the TLV571 an ideal
choice for high-speed digital signal processing.
AVAILABLE OPTIONS
PACKAGE
T
A
–40°C to 85°C TLV571IPW TLV571IDW
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
24 TSSOP
(PW)
24 SOIC
(DW)
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
Copyright 2000, Texas Instruments Incorporated
1
TLV571
I/O
DESCRIPTION
2.7 V TO 5.5 V, 1-CHANNEL, 8-BIT,
PARALLEL ANALOG-TO-DIGITAL CONVERTER
SLAS239A – SEPTEMBER 1999 – REVISED FEBRUARY 2000
functional block diagram
CLK
CS
RD
WR
CSTART
Internal
Clock
MUX
AV
DD
AIN
Input Registers
and Control Logic
REFP
8-BIT
SAR ADC
REFM DV
Three
State
Latch
DGNDAGND
DD
D0 – D5
D6/A0
D7/A1
INT/EOC
Terminal Functions
TERMINAL
NAME NO.
AGND 21 Analog ground
AIN 23 I ADC analog input
AV
DD
A0/D6 16 I/O Bidirectional 3-state data bus. D6/A0 along with D7/A1 is used as address lines to access CR0 and CR1 for
A1/D7 17 I/O Bidirectional 3-state data bus. D7/A1 along with D6/A0 is used as address lines to access CR0 and CR1 for
CLK 4 I External clock input
CS 1 I Chip select. A logic low on CS enables the TLV571.
CSTAR T 18 I Hardware sample and conversion start input. The falling edge of CSTAR T starts sampling and the rising edge
DGND 5, 8, 9 Digital ground
DV
DD
D0 – D5 10–15 I/O Bidirectional 3-state data bus
INT/EOC
NC 24 Not connected
RD
REFM 20 I Lower reference voltage (nominally ground). REFM must be supplied or REFM pin must be grounded.
REFP 19 I Upper reference voltage (nominally AVDD). The maximum input voltage range is determined by the difference
WR
22 Analog supply voltage, 2.7 V to 5.5 V
initialization.
initialization.
of CSTART
6 Digital supply voltage, 2.7 V to 5.5 V
7 O End-of-conversion/interrupt
3 I Read data. A falling edge on RD enables a read operation on the data bus when CS is low.
between the voltage applied to REFP and REFM.
2 I Write data. A rising edge on the WR latches in configuration data when CS is low. When using software
conversion start, a rising edge on WR
the ADC in nonprogrammable (hardware configuration mode).
starts conversion.
also initiates an internal sampling start pulse. When WR is tied to ground,
2
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
detailed description
analog-to-digital SAR converter
Ain
TLV571
2.7 V TO 5.5 V, 1-CHANNEL, 8-BIT,
PARALLEL ANALOG-TO-DIGITAL CONVERTER
SLAS239A – SEPTEMBER 1999 – REVISED FEBRUARY 2000
Charge
Redistribution
DAC
_
+
REFM
SAR
Register
Control
Logic
ADC Code
Figure 1
The TLV571 is a successive-approximation ADC utilizing a charge redistribution DAC. Figure 1 shows a
simplified version of the ADC.
The sampling capacitor acquires the signal on Ain during the sampling period. When the conversion process
starts, the SAR control logic and charge redistribution DAC are used to add and subtract fixed amounts of charge
from the sampling capacitor to bring the comparator into a balanced condition. When the comparator is
balanced, the conversion is complete and the ADC output code is generated.
sampling frequency, f
s
The TLV571 requires 16 CLKs for each conversion, therefore the equivalent maximum sampling frequency
achievable with a given CLK frequency is:
f
s(max)
= (1/16) f
CLK
The TL V571 is software configurable. The first two MSB bits, D(7,6) are used to address which register to set.
The remaining six bits are used as control data bits. There are two control registers, CR0 and CR1, that are user
configurable. All of the register bits are written to the control register during write cycles. A description of the
control registers is shown in Figure 2.
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
3
TLV571
2.7 V TO 5.5 V, 1-CHANNEL, 8-BIT,
PARALLEL ANALOG-TO-DIGITAL CONVERTER
SLAS239A – SEPTEMBER 1999 – REVISED FEBRUARY 2000
detailed description (continued)
control registers
A1 A0 D4 D3 D2 D1 D0D5
Control Register Zero (CR0)
A(1:0)=00
STARTSEL
D4D5 D3 D2 D1 D0
PROGEOC
CLKSEL SWPWDN Don’t Care
Don’t Care
0:
HARDWARE
START
(CSTART)
1:
SOFTWARE
START
Control Register One (CR1)
A(1:0)=01
Reserved
0:
Reserved
Bit
Always
Write 0
hardware configuration option
0:
INT
1:
EOC
D4D5 D1 D0
OSCSPD 0 Reserved 0 Reserved OUTCODE Reserved
0:
INT. OSC.
SLOW
1:
INT. OSC.
FAST
0:
Internal
Clock
1:
External
Clock
0:
Reserved
Bit
Always
Write 0
0:
NORMAL
1:
Powerdown
D3 D2
0:
Reserved
Bit,
Always
Write 0
Don’t Care
0:
Binary
1:
2’s
Complement
Don’t Care
0:
Reserved
Bit,
Always
Write 0
Figure 2. Input Data Format
The TLV571 can configure itself. This option is enabled when the WR
pin is tied to ground and a dummy RD
signal is applied. The ADC is now fully configured. Zeros or default values are applied to both control registers.
The ADC is configured ideally for 3-V operation, which means the internal OSC is set at 10 MHz and hardware
start of conversion using CSTART.
ADC conversion modes
The TLV571 provides two start of conversion modes. Table 1 explains these modes in more detail.
4
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
REGISTER
D5D4D3D2D1
D0
COMMENT
detailed description (continued)
TLV571
2.7 V TO 5.5 V, 1-CHANNEL, 8-BIT,
PARALLEL ANALOG-TO-DIGITAL CONVERTER
SLAS239A – SEPTEMBER 1999 – REVISED FEBRUARY 2000
Table 1. Conversion Modes
START OF
CONVERSION
Hardware start
(CSTAR T)
CR0.D5 = 0
Software start
CR0.D5 = 1
• Repeated conversions from AIN
• CSTART
• CSTART
• If in INT mode, one INT
• If in EOC mode, EOC will go high to low at start of conversion, and return high
at end of conversion.
• Repeated conversions from AIN
• WR
rising edge of RD
• Conversion begins after 6 clocks after sampling has begun. Thereafter, if in INT
mode, one INT
• If in EOC mode, EOC will go high to low at start of conversion and return high at
end of conversion.
falling edge to start sampling
rising edge to start conversion
rising edge to start sampling initially. Thereafter, sampling occurs at the
.
pulse generated after each conversion
OPERATION COMMENTS – FOR INPUT
CSTAR T rising edge must be applied
a minimum of 5 ns before or after CLK
rising edge.
pulse generated after each conversion
With external clock, WR and RD rising
edge must be a minimum 5 ns before
or after CLK rising edge.
configure the device
The device can be configured by writing to control registers CR0 and CR1.
Table 2. TLV571 Programming Examples
INDEX
D7 D6
EXAMPLE1
CR0 0 0 0 0 0 0 0 0 Normal, INT OSC
CR1 0 1 0 0 0 0 0 0 Binary
EXAMPLE2
CR0 0 0 0 1 1 1 0 0 Power down, EXT OSC
CR1 0 1 0 0 0 0 1 0 2’s complement output
power down
The TLV571 offers two power down modes, auto power down and software power down. This device will
automatically proceed to auto power down mode if RD is not present one clock after conversion. Software power
down is controlled directly by the user by pulling CS to DVDD.
Table 3. Power Down Modes
PARAMETERS/MODES AUTO POWER DOWN
Maximum power down dissipation current 1 mA 10 µA
Comparator Power down Power down
Clock buffer Power down Power down
Control registers Saved Saved
Minimum power down time 1 CLK 2 CLK
Minimum resume time 1 CLK 2 CLK
SOFTWARE POWER DOWN
(CS
= DVDD)
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
5
TLV571
2.7 V TO 5.5 V, 1-CHANNEL, 8-BIT,
PARALLEL ANALOG-TO-DIGITAL CONVERTER
SLAS239A – SEPTEMBER 1999 – REVISED FEBRUARY 2000
detailed description (continued)
reference voltage input
The TL V571 has two reference input pins: REFP and REFM. The voltage levels applied to these pins establish
the upper and lower limits of the analog inputs to produce a full-scale and zero-scale reading respectively . The
values of REFP, REFM, and the analog input should not exceed the positive supply or be less than GND
consistent with the specified absolute maximum ratings. The digital output is at full scale when the input signal
is equal to or higher than REFP and is at zero when the input signal is equal to or lower than REFM.
sampling/conversion
All sampling, conversion, and data output in the device are started by a trigger. This could be the RD, WR, or
CSTART signal depending on the mode of conversion and configuration. The rising edge of RD, WR, and
CSTART signal are extremely important, since they are used to start the conversion. These edges need to stay
close to the rising edge of the external clock (if it is used as CLK). The minimum setup and hold time with respect
to the rising edge of the external clock should be 5 ns minimum. When the internal clock is used, this is not an
issue since these two edges will start the internal clock automatically . Therefore, the setup time is always met.
Software controlled sampling lasts 6 clock cycles. This is done via the CLK input or the internal oscillator if
enabled. The input clock frequency can be 1 MHz to 20 MHz, translating into a sampling time from 0.6 µs to
0.3 µs. The internal oscillator frequency is 9 MHz minimum (ocillator frequency is between 9 MHz to 22 MHz),
translating into a sampling time from 0.6 µs to 0.3 µs. Conversion begins immediately after sampling and lasts
10 clock cycles. This is again done using the external clock input (1 MHz–20 MHz) or the internal oscillator
(9 MHz minimum) if enabled. Hardware controlled sampling, via CST AR T
length of the active CSTART
signal. This allows more control over the sampling time, which is useful when
sampling sources with large output impedances. On rising CSTART, conversion begins. Conversion in
hardware controlled mode also lasts 10 clock cycles. This is done using the external clock input (1 MHz–20 MHz)
or the internal oscillator (9 MHz minimum) as is the case in software controlled mode.
, begins on falling CST AR T lasts the
ExtClk
WR
OR
RD
OR
t
d(EXTCLK_CSTARTL)
CSTART
NOTE: tsu = setup time, th = hold time
Figure 3. Trigger Timing – Software Start Mode Using External Clock
≥5 ns
t
h(WRL_EXTCLKH)
t
h(RDL_EXTCLKH)
t
h(CSTARTL_EXTCLKH)
≥5 ns
t
su(WRH_EXTCLKH)
≥5 ns
t
su(RDH_EXTCLKH)
t
su(CSTARTH_EXTCLKH)
≥5 ns
≥5 ns
≥5 ns
≥5 ns
6
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
2.7 V TO 5.5 V, 1-CHANNEL, 8-BIT,
PARALLEL ANALOG-TO-DIGITAL CONVERTER
SLAS239A – SEPTEMBER 1999 – REVISED FEBRUARY 2000
start of conversion mechanism
There are two ways to convert data: hardware and software. In the hardware conversion mode the ADC begins
sampling at the falling edge of CSTART and begins conversion at the rising edge of CSTART. Software start
mode ADC samples for 6 clocks, then conversion occurs for ten clocks. The total sampling and conversion
process lasts only 16 clocks in this case. If RD
proceeds to a power-down state. Data is valid on the rising edge of INT in both conversion modes.
hardware CST ART conversion
external clock
With CS low and WR low, data is written into the ADC. The sampling begins at the falling edge of CSTART and
conversion begins at the rising edge of CST AR T. At the end of conversion, EOC goes from low to high, telling
the host that conversion is ready to be read out. The external clock is active and is used as the reference at all
times. With this mode, it is required that CST ART is not applied at the rising edge of the clock (see Figure 4).
is not detected during the next clock cycle, the ADC automatically
TLV571
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
7
8
start of conversion mechanism (continued)
CLK
t
su(CSL_WRL)
SLAS239A – SEPTEMBER 1999 – REVISED FEBRUAR Y 2000
TLV571
2.7 V to 5.5 V, 1-CHANNEL, 8-BIT
RARALLEL ANALOG-TO-DIGITAL CONVERTER
POST OFFICE BOX 655303 DALLAS, TEXAS 75265
•
OR
CS
WR
CSTART
RD
D[0:7]
INT
EOC
t
h(WRH_CSH)
t
d(CSH_CSTARTL)
t
(sample)
t
su(DAV_WRH)
Config
Data
t
h(WRH_DAV)
t
c
(10 CLKs)
t
su(CSL_RDL)
t
h(RDH_CSH)
t
c
t
(sample)
t
dis(RDH_DAV)
ADC ADC
t
en(RDL_DAV)
t
en(RDL_DAV)
t
su(CSL_RDL)
Figure 4. Input Conversion – Hardware CSTART, External Clock
Auto Powerdown
POST OFFICE BOX 655303 DALLAS, TEXAS 75265
• 9
internal clock
With CS low and WR low, data is written into the ADC. The sampling begins at the falling edge of CST AR T , and conversion begins at the rising
edge of CSTART. The internal clock turns on at the rising edge of CSTART. The internal clock is disabled after each conversion.
t
su(CSL_WRL)
CS
WR
CSTART
INTCLK
RD
D[0:7]
Config
Data
t
t
h(WRH_CSH)
t
d(CSH_CSTARTL)
t
(sample)
su(DAV_WRH)
t
h(WRH_DAV)
10
t
(STARTOSC)
10
9
t
su(CSL_RDL)
t
h(RDH_CSH)
t
dis(RDH_DAV)
ADC
Data
t
en(RDL_DAV)
t
(STARTOSC)
t
c
t
su(CSL_RDL)
ADC
Data
t
en(RDL_DAV)
P ARALLEL ANALOG-T O-DIGITAL CONVERTER
SLAS239A – SEPTEMBER 1999 – REVISED FEBRUAR Y 2000
2.7 V TO 5.5 V, 1-CHANNEL, 8-BIT
OR
INT
EOC
t
c
Auto Powerdown
Figure 5. Input Conversion – Hardware CSTART, Internal Clock
TLV571
Auto Powerdown
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