Datasheet TLV5626 Datasheet (TEXAS INSTRUMENTS)

Page 1
TLV5626
2.7-V TO 5.5-V LOW-POWER DUAL 8-BIT DIGITAL-TO-ANALOG
CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN
SLAS236A –JUNE 1999 – REVISED JUNE 2000
DIN
SCLK
CS
D PACKAGE
(TOP VIEW)
1 2 3 4
8 7 6 5
V
DD
OUTB REF AGND
features
Dual 8-Bit Voltage Output DAC
Programmable Internal Reference
Programmable Settling Time:
0.8 µs in Fast Mode ,
2.8 µs in Slow Mode
Compatible With TMS320 and SPI Serial
OUTA
Ports
Differential Nonlinearity <0.1 LSB Typ
Monotonic Over Temperature
applications
Digital Servo Control Loops
Digital Offset and Gain Adjustment
Industrial Process Control
Machine and Motion Control Devices
Mass Storage Devices
description
The TL V5626 is a dual 8-bit voltage output DAC with a flexible 3-wire serial interface.The serial interface allows glueless interface to TMS320 and SPI, QSPI, and Microwire serial ports. It is programmed with a 16-bit serial string containing 2 control and 8 data bits.
The resistor string output voltage is buffered by a x2 gain rail-to-rail output buffer . The buffer features a Class AB output stage to improve stability and reduce settling time. The programmable settling time of the DAC allows the designer to optimize speed versus power dissipation. With its on-chip programmable precision voltage reference, the TLV5626 simplifies overall system design.
Because of its ability to source up to 1 mA, the reference can also be used as a system reference. Implemented with a CMOS process, the device is designed for single supply operation from 2.7 V to 5.5 V. It is available in an 8-pin SOIC package to reduce board space in standard commercial and industrial temperature ranges.
AVAILABLE OPTIONS
PACKAGE
T
A
0°C to 70°C TLV5626CD
–40°C to 85°C TLV5626ID
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.
SOIC
(D)
SPI and QSPI are trademarks of Motorola, Inc. Microwire is a trademark of National Semiconductor Corporation.
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 1999, Texas Instruments Incorporated
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TLV5626
I/O/P
DESCRIPTION
2.7-V TO 5.5-V LOW-POWER DUAL 8-BIT DIGITAL-TO-ANALOG CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN
SLAS236A –JUNE 1999 – REVISED JUNE 2000
functional block diagram
DIN
SCLK
CS
Power-On
Reset
Serial
Interface
and
Control
Power
and Speed
Control
2
2
2-Bit
Control
Latch
8
Buffer
PGA With
Output Enable
Voltage
Bandgap
8 8
8
8-Bit
DAC A
Latch
8-Bit
DAC B
Latch
REF AGND V
8
DD
x2
x2
OUTA
OUTB
Terminal Functions
TERMINAL
NAME NO.
AGND 5 P Ground CS 3 I Chip select. Digital input active low, used to enable/disable inputs DIN 1 I Digital serial data input OUTA 4 I DAC A analog voltage output OUTB 7 O DAC B analog voltage output REF 6 I/O Analog reference voltage input/output SCLK 2 I Digital serial clock input V
DD
8 P Positive power supply
2
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Page 3
Suppl
oltage, V
Operating free-air temperature, T
°C
TLV5626
2.7-V TO 5.5-V LOW-POWER DUAL 8-BIT DIGITAL-TO-ANALOG
CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN
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absolute maximum ratings over operating free-air temperature range (unless otherwise noted)
Supply voltage (VDD to AGND) 7 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reference input voltage range – 0.3 V to VDD + 0.3 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Digital input voltage range – 0.3 V to V
DD
+ 0.3 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating free-air temperature range, TA: TLV5626C 0°C to 70°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TLV5626I –40°C to 85°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage temperature range, T
–65°C to 150°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
stg
Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds 260°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
recommended operating conditions
MIN NOM MAX UNIT
pp
y v
Power on threshold voltage, POR 0.55 2 V High-level digital input voltage, V Low-level digital input voltage, V Reference voltage, V Reference voltage, V Load resistance, R Load capacitance, C Clock frequency, f
p
NOTE 1: Due to the x2 output buffer , a reference input voltage (VDD – 0.4 V)/2 causes clipping of the transfer function. The output buffer of the
DD
IH
IL
to REF terminal VDD = 5 V (see Note 1) AGND 2.048 VDD–1.5 V
ref
to REF terminal VDD = 3 V (see Note 1) AGND 1.024 VDD–1.5 V
ref
L
L
CLK
p
internal reference must be disabled, if an external reference is used.
A
VDD = 5 V 4.5 5 5.5 V VDD = 3 V 2.7 3 3.3 V
VDD = 2.7 V to 5.5 V 2 V VDD = 2.7 V to 5.5 V 0.8 V
2 k
100 pF
20 MHz TLV5626C 0 70 TLV5626I –40 85
°
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TLV5626
DD
DD
IDDPower supply current
All inputs
AGND or V
DD
DD
PSRR
Power supply rejection ratio
dB
2.7-V TO 5.5-V LOW-POWER DUAL 8-BIT DIGITAL-TO-ANALOG CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN
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electrical characteristics over recommended operating conditions (unless otherwise noted)
power supply
PARAMETER TEST CONDITIONS MIN TYP MAX
VDD = 5 V, Int. ref.
DD
VDD = 3 V, Int. ref.
,
VDD = 5 V, Ext. ref.
VDD = 3 V, Ext. ref.
No load,
=
pp
Power-down supply current 1 µA
pp
NOTES: 2. Power supply rejection ratio at zero scale is measured by varying VDD and is given by:
PSRR = 20 log [(EZS(VDDmax) – EZS(VDDmin))/VDDmax]
3. Power supply rejection ratio at full scale is measured by varying VDD and is given by: PSRR = 20 log [(EG(VDDmax) – EG(VDDmin))/VDDmax]
p
DAC latch = 0x800
Zero scale, See Note 2 –65 Full scale, See Note 3 –65
Fast 4.2 7 mA Slow 2 3.6 mA
Fast 3.7 6.3 mA Slow 1.7 3.0 mA
Fast 3.8 6.3 mA Slow 1.7 3.0 mA
Fast 3.4 5.7 mA Slow 1.4 2.6 mA
UNIT
static DAC specifications
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
Resolution 8 bits INL Integral nonlinearity, end point adjusted See Note 4 ±0.4 ±1 LSB DNL Differential nonlinearity See Note 5 ±0.1 ±0.5 LSB E
ZS
EZS TC Zero-scale-error temperature coefficient See Note 7 10 ppm/°C E
G
EG T
NOTES: 4. The relative accuracy or integral nonlinearity (INL) sometimes referred to as linearity error, is the maximum deviation of the output
Zero-scale error (offset error at zero scale) See Note 6 ±24 mV
Gain error See Note 8 ±0.6
Gain error temperature coefficient See Note 9 10 ppm/°C
C
from the line between zero and full scale excluding the effects of zero code and full-scale errors.
5. The differential nonlinearity (DNL) sometimes referred to as differential error, is the difference between the measured and ideal 1 LSB amplitude change of any two adjacent codes. Monotonic means the output voltage changes in the same direction (or remains constant) as a change in the digital input code.
6. Zero-scale error is the deviation from zero voltage output when the digital input code is zero.
7. Zero-scale-error temperature coefficient is given by: EZSTC = [EZS(T
8. Gain error is the deviation from the ideal output (2V
9. Gain temperature coefficient is given by: EGTC = [EG(T
– 1 LSB) with an output load of 10 k excluding the effects of the zero-error .
ref
max
) – EG (T
max
min
) – EZS(T
)]/V
× 106/(T
ref
min
)]/V
max
× 106/(T
ref
– T
min
– T
min
).
max
).
% full
scale V
output specifications
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
VOOutput voltage RL = 10 k 0 VDD–0.4 V
Output load regulation accuracy VO = 4.096 V, 2.048 V, RL = 2 k vs 10 k ±0.25
% full
scale V
4
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Reference input bandwidth
REF
V
024 V dc
t
Output settling time, full scale
L
,
L
,
s
t
Output settling time, code to code
L
,
L
,
s
SR
Slew rate
L
,
L
,
V/µs
s
,
out
,
dB
TLV5626
2.7-V TO 5.5-V LOW-POWER DUAL 8-BIT DIGITAL-TO-ANALOG
CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN
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electrical characteristics over recommended operating conditions (unless otherwise noted) (Continued)
reference pin configured as output (REF)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
V
ref(OUTL)
V
ref(OUTH)
I
ref(source)
I
ref(sink)
PSRR Power supply rejection ratio –65 dB
reference pin configured as input (REF)
VIInput voltage 0 V RIInput resistance 10 M CIInput capacitance 5 pF
NOTE 10: Reference feedthrough is measured at the DAC output with an input code = 0x000.
Low reference voltage 1.003 1.024 1.045 V High reference voltage VDD > 4.75 V 2.027 2.048 2.069 V Output source current 1 mA Output sink current –1 mA Load capacitance 100 pF
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
DD–1.5
p
Reference feedthrough REF = 1 Vpp at 1 kHz + 1.024 V dc (see Note 10) –80 dB
= 0.2
pp
+ 1.
Fast 1.3 MHz Slow 525 kHz
V
digital inputs
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
I I C
High-level digital input current VI = V
IH
Low-level digital input current VI = 0 V –1 µA
IL
Input capacitance 8 pF
i
DD
1 µA
analog output dynamic performance
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
R
s(FS)
s(CC)
SNR Signal-to-noise ratio 53 57 S/(N+D) Signal-to-noise + distortion THD Total harmonic distortion SFDR Spurious free dynamic range 50 62
NOTES: 11. Settling time is the time for the output signal to remain within ±0.5 LSB of the final measured value for a digital input code change
p
p
Glitch energy
of 0x020 to 0xFD0 or 0xFD0 to 0x020 respectively. Not tested, assured by design.
12. Settling time is the time for the output signal to remain within ± 0.5 LSB of the final measured value for a digital input code change of one count. Not tested, assured by design.
13. Slew rate determines the time it takes for a change of the DAC output from 10% to 90% full-scale voltage.
= 10 kΩ,C
See Note 11 R
= 10 kΩ,C
See Note 12 R
= 10 kΩ,C
See Note 13 DIN = 0 to 1, f
CS
= V
DD
f
= 480 kSPS, f
RL = 10 kΩ,CL = 100 pF
= 100 pF,
= 100 pF,
= 100 pF,
= 100 kHz,
CLK
= 1 kHz,
Fast 0.8 2.4 Slow 2.8 5.5 Fast 0.4 1.2 Slow 0.8 1.6 Fast 12 Slow 1.8
5 nV–S
48 47
–50 –48
µ
µ
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TLV5626
2.7-V TO 5.5-V LOW-POWER DUAL 8-BIT DIGITAL-TO-ANALOG CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN
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digital input timing requirements
t
su(CS–CK)
t
su(C16-CS)
t
wH
t
wL
t
su(D)
t
h(D)
Setup time, CS low before first negative SCLK edge 10 ns Setup time, 16th negative SCLK edge (when D0 is sampled) before CS rising edge 10 ns SCLK pulse width high 25 ns SCLK pulse width low 25 ns Setup time, data ready before SCLK falling edge 10 ns Hold time, data held valid after SCLK falling edge 5 ns
PARAMETER MEASUREMENT INFORMATION
t
t
wL
wH
MIN NOM MAX UNIT
SCLK
DIN
CS
X
t
1
t
su(D)th(D)
su(CS-CK)
2 3 4 5 15 16
D15 D14 D13 D12 D1 D0 XX
t
X
su(C16-CS)
Figure 1. Timing Diagram
6
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TLV5626
2.7-V TO 5.5-V LOW-POWER DUAL 8-BIT DIGITAL-TO-ANALOG
CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN
SLAS236A –JUNE 1999 – REVISED JUNE 2000
TYPICAL CHARACTERISTICS
SUPPLY CURRENT
vs
FREE-AIR TEMPERATURE
4.5
4
Fast Mode
3.5
3
2.5
– Supply Current – mA
2
DD
I
1.5
1
0.5 –40–30 –20 –10 0 10 20
TA – Free-Air Temperature – °C
Slow Mode
VDD = 5 V V
= Int. 2 V
ref
Input Code = 1023 (Both DACs)
Figure 2
POWER DOWN SUPPLY CURRENT
vs
TIME
2.6
2.4
2.2 2
1.8
1.6
1.4
1.2 1
0.8
0.6
– Power Down Supply Current – mA
0.4
DD
I
0.2 0
010203040
t – Time – µs
Figure 4
30 40 50 90
60 70 80
50 60 70 80
SUPPLY CURRENT
FREE-AIR TEMPERATURE
4.5
4
3.5
3
2.5
– Supply Current – mA
2
DD
I
1.5
1
0.5 –40–30 –20 –10 0 10 20
Fast Mode
VDD = 3 V V
ref
Input Code = 1023 (Both DACs)
TA – Free-Air Temperature – °C
Figure 3
OUTPUT VOLTAGE
LOAD CURRENT
2.064
2.062
2.06
2.058
2.056
– Output Voltage – V
O
2.054
V
2.052
2.05 0 0.5 1 1.5 2 2.5 3
Fast Mode
Slow Mode
Source Current – mA
Figure 5
vs
Slow Mode
= Int. 1 V
30 40 50 90
60 70 80
vs
VDD = 3 V V
= Int. 1 V
ref
Input Code = 4095
3.5 4
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TLV5626
0
2.7-V TO 5.5-V LOW-POWER DUAL 8-BIT DIGITAL-TO-ANALOG CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN
SLAS236A –JUNE 1999 – REVISED JUNE 2000
TYPICAL CHARACTERISTICS
OUTPUT VOLTAGE
LOAD CURRENT
4.128
4.126
4.124
4.122
4.12
– Output Voltage – V
O
4.118
V
4.116
4.114 0 0.5 1 1.5 2 2.5 3
Fast Mode
Slow Mode
Source Current – mA
Figure 6
OUTPUT VOLTAGE
LOAD CURRENT
5
VDD = 5 V V
4.5 4
= Int. 2 V
ref
Input Code = 0
vs
VDD = 5 V V
ref
Input Code = 4095
vs
= Int. 2 V
3.5 4
OUTPUT VOLTAGE
vs
LOAD CURRENT
3
VDD = 3 V V
= Int. 1 V
ref
Input Code = 0
2.5
2
1.5
1
– Output Voltage – V
O
V
0.5
0
0 0.5 1 1.5 2 2.5 3
Fast Mode
Slow Mode
Sink Current – mA
Figure 7
TOTAL HARMONIC DISTORTION AND NOISE
vs
FREQUENCY
0
–10 –20
VDD = 5 V V
= 1 V dc + 1 V p/p Sinewave
ref
Output Full Scale
3.5 4
– Output Voltage – V
O
V
8
3.5
Fast Mode
3
2.5 2
1.5
1
0.5 0
0 0.5 1 1.5 2 2.5 3
Sink Current – mA
Figure 8
–30
–40 –50
–60
–70 –80
Slow Mode
3.5 4
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–90
–100
THD+N – Total Harmonic Distortion and Noise – dB
100 1000
f – Frequency – Hz
Figure 9
Slow Mode
Fast Mode
10000 10000
Page 9
TLV5626
2.7-V TO 5.5-V LOW-POWER DUAL 8-BIT DIGITAL-TO-ANALOG
CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN
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TYPICAL CHARACTERISTICS
TOTAL HARMONIC DISTORTION
vs
FREQUENCY
0
–10 –20
–30
–40 –50
–60
VDD = 5 V V
= 1 V dc + 1 V p/p Sinewave
ref
Output Full Scale
–70 –80
THD – Total Harmonic Distortion – dB
–90
–100
100 1000
0.20
0.15
0.10
0.05 –0.00 –0.05 –0.10 –0.15
–0.2
DNL – Differential Nonlinearity – LSB
0 16 32 48 64 80 96 112 128 144 160 176 192 208 224 240 256
Slow Mode
Fast Mode
10000 100000
f – Frequency – Hz
Figure 10
DIFFERENTIAL NONLINEARITY
vs
DIGITAL OUTPUT CODE
Digital Output Code
Figure 11
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TLV5626
2.7-V TO 5.5-V LOW-POWER DUAL 8-BIT DIGITAL-TO-ANALOG CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN
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TYPICAL CHARACTERISTICS
INTEGRAL NONLINEARITY
vs
DIGITAL OUTPUT CODE
1.0
0.8
0.6
0.4
0.2 –0.0 –0.2 –0.4 –0.6 –0.8
INL – Integral Nonlinearity – LSB
–1.0
0 16 32 48 64 80 96 112 128 144 160 176 192 208 224 240 256
Digital Output Code
Figure 12
APPLICATION INFORMATION
general function
The TLV5626 is a dual 8-bit, single supply DAC, based on a resistor string architecture. It consists of a serial interface, a speed and power-down control logic, a programmable internal reference, a resistor string, and a rail-to-rail output buffer.
The output voltage (full scale determined by reference) is given by:
2REF
CODE
0x1000
[V]
Where REF is the reference voltage and CODE is the digital input value in the range 0x000 to 0xFF0.Bits 3 to 0 must be set to zero. A power-on reset initially puts the internal latches to a defined state (all bits zero).
serial interface
A falling edge of CS starts shifting the data bit-per-bit (starting with the MSB) to the internal register on the falling edges of SCLK. After 16 bits have been transferred or CS rises, the content of the shift register is moved to the target latches (DAC A, DAC B, BUFFER, CONTROL), depending on the control bits within the data word.
Figure 13 shows examples of how to connect the TLV5626 to TMS320, SPI, and Microwire.
10
TMS320
DSP
CLKX
FSX
DX
TLV5626 CS DIN SCLK
SPI
I/O
MOSI
SCK
TLV5626 CS DIN SCLK
Figure 13. Three-Wire Interface
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Microwire
I/O SO SK
TLV5626 CS DIN SCLK
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CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN
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APPLICATION INFORMATION
Notes on SPI and Microwire: Before the controller starts the data transfer, the software has to generate a falling edge on the I/O pin connected to CS. If the word width is 8 bits (SPI and Microwire), two write operations must be performed to program the TL V5626. After the write operation(s), the holding registers or the control register are updated automatically on the 16
serial clock frequency and update rate
The maximum serial clock frequency is given by:
th
positive clock edge.
TLV5626
f
sclkmax
+
t
whmin
)
1
t
wlmin
+
20 MHz
The maximum update rate is:
whmin
1
)
t
wlmin
+
Ǔ
1.25 MHz
f
updatemax
+
16ǒt
The maximum update rate is just a theoretical value for the serial interface, as the settling time of the TL V5626 has to be considered, too.
data format
The 16-bit data word for the TLV5626 consists of two parts:
Program bits (D15..D12)
New data (D11..D0)
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
R1 SPD PWR R0 12 Data bits
SPD: Speed control bit 1 fast mode 0 slow mode PWR: Power control bit 1 power down 0 normal operation
The following table lists the possible combination of the register select bits:
register select bits
R1 R0 REGISTER
0 0 Write data to DAC B and BUFFER 0 1 Write data to BUFFER 1 0 Write data to DAC A and update DAC B with BUFFER content 1 1 Write data to control register
The meaning of the 12 data bits depends on the register. If one of the DAC registers or the BUFFER is selected, then the 12 data bits determine the new DAC value:
data bits: DAC A, DAC B and BUFFER
D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
New DAC Value 0 0 0 0
If control is selected, then D1, D0 of the 12 data bits are used to program the reference voltage:
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APPLICATION INFORMATION
data bits: CONTROL
D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
X X X X X X X X X X REF1 REF0
X: don’t care
REF1 and REF0 determine the reference source and, if internal reference is selected, the reference voltage.
reference bits
REF1 REF0 REFERENCE
0 0 External 0 1 1.024 V 1 0 2.048 V 1 1 External
CAUTION:
If external reference voltage is applied to the REF pin, external reference MUST be selected.
examples of operation:
Set DAC A output, select fast mode, select internal reference at 2.048 V:
1. Set reference voltage to 2.048 V (CONTROL register):
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
1 1 0 1 0 0 0 0 0 0 0 0 0 0 1 0
2. Write new DAC A value and update DAC A output:
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
1 1 0 0 New DAC A output value 0 0 0 0
The DAC A output is updated on the rising clock edge after D0 is sampled. T o output data consecutively using the same DAC configuration, it is not necessary to program the CONTROL
register again.
Set DAC B output, select fast mode, select external reference:
3. Select external reference (CONTROL register):
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
1 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0
4. Write new DAC B value to BUFFER and update DAC B output:
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
0 1 0 0 New BUFFER content and DAC B output value 0 0 0 0
X = Don’t care
The DAC A output is updated on the rising clock edge after D0 is sampled. T o output data consecutively using the same DAC configuration, it is not necessary to program the CONTROL
register again.
12
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2.7-V TO 5.5-V LOW-POWER DUAL 8-BIT DIGITAL-TO-ANALOG
CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN
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APPLICATION INFORMATION
examples of operation: (continued)
Set DAC A value, set DAC B value, update both simultaneously , select slow mode, select internal reference at 1.024 V:
1. Set reference voltage to 1.024 V (CONTROL register):
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
1 0 0 1 0 0 0 0 0 0 0 0 0 0 0 1
2. Write data for DAC B to BUFFER:
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
0 0 0 1 New DAC B value 0 0 0 0
X = Don’t care
3. Write new DAC A value and update DAC A and B simultaneously:
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
1 0 0 0 New DAC A value 0 0 0 0
X = Don’t care
Both outputs are updated on the rising clock edge after D0 from the DAC A data word is sampled.
Set power-down mode:
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
X X 1 X X X X X X X X X X X X X
X = Don’t care
linearity, offset, and gain error using single ended supplies
When an amplifier is operated from a single supply , the voltage offset can still be either positive or negative. With a positive offset, the output voltage changes on the first code change. With a negative offset, the output voltage may not change with the first code, depending on the magnitude of the offset voltage.
The output amplifier attempts to drive the output to a negative voltage. However, because the most negative supply rail is ground, the output cannot drive below ground and clamps the output at 0 V.
The output voltage then remains at zero until the input code value produces a sufficient positive output voltage to overcome the negative offset voltage, resulting in the transfer function shown in Figure 14.
Output
Voltage
0 V
Negative
Offset
DAC Code
Figure 14. Effect of Negative Offset (single supply)
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TLV5626
2.7-V TO 5.5-V LOW-POWER DUAL 8-BIT DIGITAL-TO-ANALOG CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN
SLAS236A –JUNE 1999 – REVISED JUNE 2000
APPLICATION INFORMATION
This offset error , not the linearity error, produces this breakpoint. The transfer function would have followed the dotted line if the output buffer could drive below the ground rail.
For a DAC, linearity is measured between zero-input code (all inputs 0) and full-scale code (all inputs 1) after offset and full scale are adjusted out or accounted for in some way . However , single supply operation does not allow for adjustment when the offset is negative due to the breakpoint in the transfer function. So the linearity is measured between full-scale code and the lowest code that produces a positive output voltage.
definitions of specifications and terminology
integral nonlinearity (INL)
The relative accuracy or integral nonlinearity (INL), sometimes referred to as linearity error, is the maximum deviation of the output from the line between zero and full scale excluding the effects of zero code and full-scale errors.
differential nonlinearity (DNL)
The differential nonlinearity (DNL), sometimes referred to as differential error, is the difference between the measured and ideal 1 LSB amplitude change of any two adjacent codes. Monotonic means the output voltage changes in the same direction (or remains constant) as a change in the digital input code.
zero-scale error (EZS)
Zero-scale error is defined as the deviation of the output from 0 V at a digital input value of 0.
gain error (E
Gain error is the error in slope of the DAC transfer function.
signal-to-noise ratio + distortion (S/N+D)
S/N+D is the ratio of the rms value of the measured input signal to the rms sum of all other spectral components below the Nyquist frequency, including harmonics but excluding dc. The value for S/N+D is expressed in decibels.
spurious free dynamic range (SFDR)
Spurious free dynamic range is the difference between the rms value of the output signal and the rms value of the spurious signal within a specified bandwidth. The value for SFDR is expressed in decibels.
)
G
14
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Page 15
TLV5626
2.7-V TO 5.5-V LOW-POWER DUAL 8-BIT DIGITAL-TO-ANALOG
CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN
SLAS236A –JUNE 1999 – REVISED JUNE 2000
MECHANICAL DATA
D (R-PDSO-G**) PLASTIC SMALL-OUTLINE PACKAGE
14 PINS SHOWN
0.050 (1,27)
14
1
0.069 (1,75) MAX
0.020 (0,51)
0.014 (0,35) 8
7
A
0.010 (0,25)
0.004 (0,10)
DIM
0.157 (4,00)
0.150 (3,81)
PINS **
0.010 (0,25)
0.244 (6,20)
0.228 (5,80)
8
M
Seating Plane
0.004 (0,10)
14
0.008 (0,20) NOM
0°–8°
16
Gage Plane
0.010 (0,25)
0.044 (1,12)
0.016 (0,40)
A MAX
A MIN
NOTES: A. All linear dimensions are in inches (millimeters).
B. This drawing is subject to change without notice. C. Body dimensions do not include mold flash or protrusion, not to exceed 0.006 (0,15). D. Falls within JEDEC MS-012
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0.197
(5,00)
0.189
(4,80)
0.344
(8,75)
0.337
(8,55)
0.394
(10,00)
0.386
(9,80)
4040047/D 10/96
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