TI ADS5547

ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
14-BIT, 210 MSPS ADC WITH DDR LVDS/CMOS OUTPUTS
FEATURES
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Maximum Sample Rate: 210 MSPS
14-Bit Resolution
No Missing Codes
Total Power Dissipation 1.23 W
Internal Sample and Hold
73.3-dBFS SNR at 70-MHz IF
85-dBc SFDR at 70-MHz IF, 0 dB gain
High Analog Bandwidth up to 800 MHz
Double Data Rate (DDR) LVDS and Parallel
CMOS Output Options
Programmable Gain up to 6 dB for SNR/SFDR
Trade-Off at High IF
Reduced Power Modes at Lower Sample
Rates
Supports Input Clock Amplitude Down to
400 mVPP
Clock Duty Cycle Stabilizer
No External Reference Decoupling Required
Internal and External Reference Support
Programmable Output Clock Position to Ease
Data Capture
3.3-V Analog and Digital Supply
48-QFN Package (7 mm × 7 mm)
DESCRIPTION
ADS5547 is a high performance 14-bit, 210-MSPS
A/D converter. It offers state-of-the art functionality
and performance using advanced techniques to
minimize board space. With high analog bandwidth
and low jitter input clock buffer, the ADC supports
both high SNR and high SFDR at high input
frequencies. It features programmable gain options
that can be used to improve SFDR performance at
lower full-scale analog input ranges.
In a compact 48-pin QFN, the device offers fully
differential LVDS DDR (Double Data Rate) interface
while parallel CMOS outputs can also be selected.
Flexible output clock position programmability is
available to ease capture and trade-off setup for hold
times. At lower sampling rates, the ADC can be
operated at scaled down power with no loss in
performance. The ADS5547 includes an internal
reference, while eliminating the traditional reference
pins and associated external decoupling. The device
also supports an external reference mode.
The device is specified over
temperature range (-40°C to 85°C).
the
industrial
ADS5547 PRODUCT FAMILY
210 MSPS
190 MSPS
170 MSPS
14 bit
ADS5547
ADS5546
ADS5545
12 bit
ADS5527
-
ADS5525
APPLICATIONS
•
•
•
•
•
•
•
•
Wireless Communications Infrastructure
Software Defined Radio
Power Amplifier Linearization
802.16d/e
Test and Measurement Instrumentation
High Definition Video
Medical Imaging
Radar Systems
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.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2006, Texas Instruments Incorporated
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.
CLKP
DRGND
DRVDD
AGND
AVDD
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be
more susceptible to damage because very small parametric changes could cause the device not to meet its published
specifications.
CLKOUTP
CLOCKGEN
CLKM
CLKOUTM
D0_D1_P
D0_D1_M
D2_D3_P
D2_D3_M
D4_D5_P
D4_D5_M
Digital
Encoder
and
Serializer
INP
14-Bit
ADC
SHA
INM
D6_D7_P
D6_D7_M
D8_D9_P
D8_D9_M
D10_D11_P
D10_D11_M
VCM
Control
Interface
Reference
D12_D13_P
D12_D13_M
OVR
MODE
OE
DFS
RESET
SEN
SDATA
SCLK
IREF
ADS5547
LVDS MODE
PACKAGE/ORDERING INFORMATION (1)
PRODUCT
PACKAGELEAD
ADS5547
QFN-48 (2)
(1)
(2)
2
PACKAGE
DESIGNATOR
RGZ
SPECIFIED
TEMPERATURE
RANGE
–40°C to 85°C
PACKAGE
MARKING
ORDERING
NUMBER
TRANSPORT
MEDIA,
QUANTITY
ADS5547IRGZT
Tape and Reel,
250
ADS5547IRGZR
Tape and Reel,
2500
AZ5547
For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI
Web site at www.ti.com.
For thermal pad size on the package, see the mechanical drawings at the end of this data sheet. θJA = 25.41°C/W (0 LFM air flow),
θJC = 16.5°C/W when used with 2 oz. copper trace and pad soldered directly to a JEDEC standard four layer 3 in x 3 in PCB.
Submit Documentation Feedback
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
ABSOLUTE MAXIMUM RATINGS (1)
over operating free-air temperature range (unless otherwise noted)
VALUE
UNIT
Supply voltage range, AVDD
–0.3 V to 3.9
V
Supply voltage range, DRVDD
–0.3 V to 3.9
V
Voltage between AGND and DRGND
-0.3 to 0.3
V
Voltage between AVDD to DRVDD
-0.3 to 3.3
V
Voltage applied to VCM pin (in external reference mode)
-0.3 to 1.8
V
–0.3 V to minimum (3.6, AVDD + 0.3 V)
V
Voltage applied to analog input pins, INP and INM
Voltage applied to input clock pins, CLKP and CLKM
TA
Operating free-air temperature range
TJ
Operating junction temperature range
Tstg
Storage temperature range
(1)
-0.3 V to AVDD + 0.3 V
V
–40 to 85
°C
125
°C
–65 to 150
°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
over operating free-air temperature range (unless otherwise noted)
MIN
TYP
MAX
UNIT
Analog supply voltage, AVDD
3
3.3
3.6
V
Digital supply voltage, DRVDD
3
3.3
3.6
V
SUPPLIES
ANALOG INPUTS
Differential input voltage range
2
VPP
1.5 ±0.1
Input common-mode voltage
Voltage applied on VCM in external reference mode
1.45
1.5
V
1.55
V
CLOCK INPUT
Input clock sample rate
(1)
MSPS
DEFAULT SPEED mode
50
210
1
60
LOW SPEED mode
MSPS
Input clock amplitude differential (V(CLKP) - V(CLKM))
Sine wave, ac-coupled
0.4
1.5
VPP
LVPECL, ac-coupled
1.6
VPP
LVDS, ac-coupled
0.7
VPP
LVCMOS, single-ended, ac-coupled
3.3
V
Input clock duty cycle (See Figure 31)
35%
50%
65%
DIGITAL OUTPUTS
CL
Maximum external load capacitance from each output pin to DRGND (LVDS and CMOS modes)
Without internal termination (default after
reset)
With 100 Ω internal termination
RL
(2)
Differential load resistance between the LVDS output pairs (LVDS mode)
Operating free-air temperature
(1)
(2)
–40
5
pF
10
pF
100
Ω
85
°C
See the section on Low Sampling Frequency Operation for more information.
See the section on LVDS Buffer Internal termination for more information.
Submit Documentation Feedback
3
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
ELECTRICAL CHARACTERISTICS
Typical values are at 25°C, min and max values are across the full temperature range TMIN = –40°C to TMAX = 85°C,
AVDD = DRVDD = 3.3 V, sampling rate = 210 MSPS, sine wave input clock, 1.5 VPP differential clock amplitude, 50% clock
duty cycle, –1 dBFS differential analog input, internal reference mode, 0 db gain, DDR LVDS data output (unless otherwise
noted)
PARAMETER
TEST CONDITIONS
MIN
Resolution
TYP
MAX
UNIT
14
bits
Differential input voltage range
2
VPP
Differential input capacitance
7
pF
ANALOG INPUT
Analog input bandwidth
800
MHz
Analog input common mode current
(per input pin)
342
µA
REFERENCE VOLTAGES
V(REFB)
Internal reference bottom voltage
Internal reference mode
0.5
V
V(REFT)
Internal reference top voltage
Internal reference mode
2.5
V
VCM
Common mode output voltage
Internal reference mode
1.5
V
VCM output current capability
Internal reference mode
±4
mA
DC ACCURACY
No Missing Codes
DNL
Differential non-linearity
INL
Integral non-linearity
Assured
Offset error
0.5
2.5
LSB
-5
3.5
5
LSB
5
Offset temperature coefficient
mV
0.002
Gain error
Gain temperature coefficient
PSRR
-0.95
DC Power supply rejection ratio
ppm/°C
±1
%FS
0.01
∆%/°C
0.6
mV/V
POWER SUPPLY
I(AVDD)
I(DRVDD)
ICC
4
Analog supply current
Digital supply current
306
mA
LVDS mode, IO = 3.5 mA,
RL = 100 Ω, CL = 5 pF
66
mA
CMOS mode, FIN = 2.5 MHz,
CL = 5 pF
47
mA
mA
Total supply current
LVDS mode
372
Total power dissipation
LVDS mode
1.23
1.375
Standby power
In STANDBY mode with clock stopped
100
150
mW
Clock stop power
With input clock stopped
100
150
mW
Submit Documentation Feedback
W
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
ELECTRICAL CHARACTERISTICS
Typical values are at 25°C, min and max values are across the full temperature range TMIN = –40°C to TMAX = 85°C,
AVDD = DRVDD = 3.3 V, sampling rate = 210 MSPS, sine wave input clock, 1.5 VPP differential clock amplitude, 50% clock
duty cycle, –1 dBFS differential analog input, internal reference mode, 0 db gain, DDR LVDS data output (unless otherwise
noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
AC CHARACTERISTICS
FIN = 20 MHz
73.6
FIN = 70 MHz
71
FIN = 100 MHz
72.9
FIN = 170 MHz
SNR
Signal to noise ratio
FIN = 230 MHz
FIN = 300 MHz
FIN = 400 MHz
RMS output noise
71.7
0 dB gain, 2 VPP FS (1)
71
3 dB gain, 1.4 VPP FS
69.1
0 dB gain, 2 VPP FS
3 dB gain, 1.4 VPP FS
68.6
0 dB gain, 2 VPP FS
68.5
3 dB gain, 1.4 VPP FS
67.7
Inputs tied to common-mode
1.18
76
FIN = 100 MHz
FIN = 300 MHz
FIN = 400 MHz
79
0 dB gain, 2 VPP FS
75
3 dB gain, 1.4 VPP FS
78
0 dB gain, 2 VPP FS
74
3 dB gain, 1.4 VPP FS
76
0 dB gain, 2 VPP FS
68
3 dB gain, 1.4 VPP FS
70
FIN = 20 MHz
70
FIN = 100 MHz
Signal to noise and distortion ratio
FIN = 300 MHz
FIN = 400 MHz
70.7
0 dB gain, 2 VPP FS
69
3 dB gain, 1.4 VPP FS
68.7
0 dB gain, 2 VPP FS
67.8
3 dB gain, 1.4 VPP FS
67.6
0 dB gain, 2 VPP FS
63.5
3 dB gain, 1.4 VPP FS
64.3
FIN = 20 MHz
76
FIN = 100 MHz
Second harmonic
FIN = 300 MHz
FIN = 400 MHz
(1)
90
90
FIN = 170 MHz
HD2
dBFS
92
FIN = 70 MHz
FIN = 230 MHz
72.6
71.1
FIN = 170 MHz
SINAD
dBc
73
FIN = 70 MHz
FIN = 230 MHz
85
78
FIN = 170 MHz
FIN = 230 MHz
LSB
87
FIN = 70 MHz
Spurious free dynamic range
dBFS
70
FIN = 20 MHz
SFDR
73.3
88
0 dB gain, 2 VPP FS
86
3 dB gain, 1.4 VPP FS
88
0 dB gain, 2 VPP FS
78
3 dB gain, 1.4 VPP FS
80
0 dB gain, 2 VPP FS
69
3 dB gain, 1.4 VPP FS
71
dBc
FS = Full scale range
Submit Documentation Feedback
5
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
ELECTRICAL CHARACTERISTICS (continued)
Typical values are at 25°C, min and max values are across the full temperature range TMIN = –40°C to TMAX = 85°C,
AVDD = DRVDD = 3.3 V, sampling rate = 210 MSPS, sine wave input clock, 1.5 VPP differential clock amplitude, 50% clock
duty cycle, –1 dBFS differential analog input, internal reference mode, 0 db gain, DDR LVDS data output (unless otherwise
noted)
PARAMETER
TEST CONDITIONS
MIN
FIN = 20 MHz
76
FIN = 100 MHz
FIN = 230 MHz
FIN = 300 MHz
FIN = 400 MHz
Worst harmonic (other than HD2, HD3)
Total harmonic distortion
79
75
3 dB gain, 1.4 VPP FS
78
0 dB gain, 2 VPP FS
74
3 dB gain, 1.4 VPP FS
76
0 dB gain, 2 VPP FS
68
3 dB gain, 1.4 VPP FS
70
FIN = 20 MHz
95
FIN = 70 MHz
92
FIN = 100 MHz
92
FIN = 170 MHz
90
FIN = 230 MHz
90
FIN = 300 MHz
88
FIN = 400 MHz
87
FIN = 20 MHz
83
74
IMD
PSRR
6
Effective number of bits
77
FIN = 170 MHz
77
FIN = 230 MHz
74
FIN = 300 MHz
72
Two-tone intermodulation distortion
FIN = 70 MHz
FIN1 = 50.03 MHz, FIN2 = 46.03 MHz,
-7 dBFS each tone
FIN1 = 190.1 MHz, FIN2 = 185.02 MHz,
-7 dBFS each tone
AC power supply rejection ratio
30 MHz, 200 mVPP signal on 3.3-V supply
Voltage overload recovery time
Recovery to 1% (of final value) for 6-dB overload
with sine-wave input at Nyquist frequency
Submit Documentation Feedback
dBc
dBc
82
FIN = 100 MHz
FIN = 400 MHz
ENOB
85
0 dB gain, 2 VPP FS
FIN = 70 MHz
THD
UNIT
78
FIN = 170 MHz
Third harmonic
MAX
87
FIN = 70 MHz
HD3
TYP
dBc
65
11.3
11.8
bits
91.1
dBFS
86.5
35
dBc
1
Clock
cycles
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
DIGITAL CHARACTERISTICS
(1)
The DC specifications refer to the condition where the digital outputs are not switching, but are permanently at a valid logic
level 0 or 1 AVDD = DRVDD = 3.3 V, IO = 3.5 mA, RL = 100 Ω (2)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
DIGITAL INPUTS
High-level input voltage
2.4
V
Low-level input voltage
0.8
V
High-level input current
33
µA
Low-level input current
–33
µA
4
pF
High-level output voltage
3.3
V
Low-level output voltage
0
V
2
pF
1375
mV
Input capacitance
DIGITAL OUTPUTS – CMOS MODE
Output capacitance
Output capacitance inside the device, from each output to
ground
DIGITAL OUTPUTS – LVDS MODE
High-level output voltage
Low-level output voltage
1025
Output differential voltage, |VOD|
225
VOS Output offset voltage, single-ended
Common-mode voltage of OUTP and OUTM
Output capacitance
Output capacitance inside the device, from either output to
ground
(1)
(2)
350
mV
425
mV
1200
mV
2
pF
All LVDS and CMOS specifications are characterized, but not tested at production.
IO refers to the LVDS buffer current setting, RL is the differential load resistance between the LVDS output pair.
TIMING CHARACTERISTICS – LVDS AND CMOS MODES (1)
Typical values are at 25°C, min and max values are across the full temperature range TMIN = –40°C to TMAX = 85°C, AVDD =
DRVDD = 3.3 V, sampling frequency = 210 MSPS, sine wave input clock, 1.5 VPP clock amplitude, CL = 5 pF (2), IO = 3.5 mA,
RL = 100 Ω (3), no internal termination, unless otherwise noted.
For timings at lower sampling frequencies, see the Output Timing section in the APPLICATION INFORMATION of this data
sheet.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
ta
Aperture delay
1.2
ns
tj
Aperture jitter
150
fs rms
Wake-up time
Time to valid data after coming out of
STANDBY mode
100
Time to valid data after stopping and
restarting the input clock
100
µs
14
clock
cycles
1.0
1.5
ns
0.35
0.8
ns
Latency
DDR LVDS MODE (4)
tsu
th
(1)
(2)
(3)
(4)
(5)
(6)
Data setup time (5)
Data valid
(6)
Data hold time (5)
Zero-cross of CLKOUTP to data becoming
invalid (6)
to zero-cross of CLKOUTP
Timing parameters are specified by design and characterization and not tested in production.
CL is the effective external single-ended load capacitance between each output pin and ground.
IO refers to the LVDS buffer current setting; RL is the differential load resistance between the LVDS output pair.
Measurements are done with a transmission line of 100 Ω characteristic impedance between the device and the load.
Setup and hold time specifications take into account the effect of jitter on the output data and clock. These specifications also assume
that the data and clock paths are perfectly matched within the receiver. Any mismatch in these paths within the receiver would appear
as reduced timing margin.
Data valid refers to logic high of +50 mV and logic low of –50 mV.
Submit Documentation Feedback
7
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
TIMING CHARACTERISTICS – LVDS AND CMOS MODES (continued)
For timings at lower sampling frequencies, see the Output Timing section in the APPLICATION INFORMATION of this data
sheet.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
3.7
4.4
5.1
45%
50%
55%
UNIT
Clock propagation delay (7)
Input clock rising edge zero-cross to
output clock rising edge zero-cross
LVDS bit clock duty cycle
Duty cycle of differential clock,
(CLKOUTP-CLKOUTM)
80 ≤ Fs ≤ 210 MSPS
tr ,
tf
Data rise time,
Data fall time
Rise time measured from –50 mV to 50
mV
Fall time measured from 50 mV to –50 mV
1 ≤ Fs ≤ 210 MSPS
50
100
200
ps
tCLKRISE,
tCLKFALL
Output clock rise time,
Output clock fall time
Rise time measured from –50 mV to 50
mV
Fall time measured from 50 mV to –50 mV
1 ≤ Fs ≤ 210 MSPS
50
100
200
ps
Output clock jitter
Cycle-to-cycle jitter
Output enable (OE) to valid data
delay
Time to valid data after OE becomes
active
tPDI
tOE
120
ns
ps pp
1
µs
PARALLEL CMOS MODE
Data valid (8) to 50% of CLKOUT rising
edge
1.8
2.6
50% of CLKOUT rising edge to data
becoming invalid (10)
0.4
0.8
Clock propagation delay (11)
Input clock rising edge zero-cross to 50%
of CLKOUT rising edge
2.6
3.4
Output clock duty cycle
Duty cycle of output clock (CLKOUT)
80 ≤ Fs ≤ 210 MSPS
Data rise time,
Data fall time
Rise time measured from 20% to 80% of
DRVDD
Fall time measured from 80% to 20% of
DRVDD
1 ≤ Fs ≤ 210 MSPS
0.8
tCLKRISE,
tCLKFALL
Output clock rise time,
Output clock fall time
Rise time measured from 20% to 80% of
DRVDD
Fall time measured from 80% to 20% of
DRVDD
1 ≤ Fs ≤ 210 MSPS
0.4
tOE
Output enable (OE) to valid data
delay
Time to valid data after OE becomes
active
tsu
Data setup time
th
Data hold time
tPDI
tr ,
tf
(5)
(9)
(7)
ns
ns
4.2
ns
1.5
2.0
ns
0.8
1.2
ns
50
ns
45%
To use the input clock as the data capture clock, it is necessary to delay the input clock by a delay (tD) to get the desired setup and hold
times. Use either of these equations to calculate tD:
Desired setup time = tD - (tPDI - tsu )
Desired hold time = (tPDI + th ) - tD
(8) Data valid refers to logic high of 2 V and logic low of 0.8 V
(9) Setup and hold time specifications take into account the effect of jitter on the output data and clock. These specifications also assume
that the data and clock paths are perfectly matched within the receiver. Any mismatch in these paths within the receiver would appear
as reduced timing margin.
(10) Data valid refers to logic high of 2 V and logic low of 0.8 V
(11) To use the input clock as the data capture clock, it is necessary to delay the input clock by a delay (tD) to get the desired setup and hold
times. Use either of these equations to calculate tD:
Desired setup time = tD - (tPDI - tsu )
Desired hold time = (tPDI + th ) - tD
8
Submit Documentation Feedback
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
N+4
N+3
N+2
N+1
Sample
N
N+17
N+16
N+15
N+14
Input
Signal
ta
Input
Clock
CLKP
CLKM
CLKOUTM
CLKOUTP
tsu
Output Data
DXP, DXM
E
O
E – Even Bits D0,D2,D4,D6,D8,D10,D12
O – Odd Bits D1,D3,D5,D7,D9,D11,D13
E
O
N–14
E
O
N–13
E
O
N–12
E
tPDI
th
14 Clock Cycles
DDR
LVDS
O
N–11
E
N–10
O
E
O
E
O
N
N–1
E
E
O
O
N+2
N+1
tPDI
CLKOUT
tsu
Parallel
CMOS
14 Clock Cycles
Output Data
D0–D13
N–14
N–13
N–12
N–11
th
N–10
N–1
N
N+1
N+2
Figure 1. Latency
Submit Documentation Feedback
9
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
CLKM
Input
Clock
CLKP
tPDI
Output
Clock
CLKOUTP
CLKOUTM
tsu
th
tsu
Output
Data Pair
(1)
(2)
Dn
Dn_Dn+1_P,
Dn_Dn+1_M
th
Dn
(1)
Dn+1
– Bits D0, D2, D4, D6, D8, D10, D12
Dn+1 – Bits D1, D3, D5, D7, D9, D11, D13
Figure 2. LVDS Mode Timing
CLKM
Input
Clock
CLKP
tPDI
Output
Clock
CLKOUT
th
tsu
Output
Data
Dn
Dn
(1)
(1)
Dn – Bits D0–D13
Figure 3. CMOS Mode Timing
10
Submit Documentation Feedback
(2)
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
DEVICE PROGRAMMING MODES
ADS5547 offers flexibility with several programmable features that are easily configured.
The device can be configured independently using either parallel interface control or serial interface
programming.
In addition, the device supports a third configuration mode, where both the parallel interface and the serial
control registers are used. In this mode, the priority between the parallel and serial interfaces is determined by a
priority table (Table 2). If this additional level of flexibility is not required, the user can select either the serial
interface programming or the parallel interface control.
USING PARALLEL INTERFACE CONTROL ONLY
To control the device using parallel interface, keep RESET tied to high (DRVDD). Pins DFS, MODE, SEN,
SCLK, and SDATA are used to directly control certain modes of the ADC. The device is configured by
connecting the parallel pins to the correct voltage levels (as described in Table 3 to Table 7). There is no need
to apply reset.
In this mode, SEN, SCLK, and SDATA function as parallel interface control pins. Frequently used functions are
controlled in this mode—standby, selection between LVDS/CMOS output format, internal/external reference,
two's complement/straight binary output format, and position of the output clock edge.
Table 1 has a description of the modes controlled by the four parallel pins.
Table 1. Parallel Pin Definition
PIN
DFS
MODE
CONTROL MODES
DATA FORMAT and the LVDS/CMOS output interface
Internal or external reference
SEN
CLKOUT edge programmability
SCLK
LOW SPEED mode control for low sampling frequencies (< 50 MSPS)
SDATA
STANDBY mode – Global (ADC, internal references and output buffers are powered down)
USING SERIAL INTERFACE PROGRAMMING ONLY
To program using the serial interface, the internal registers must first be reset to their default values, and the
RESET pin must be kept low. In this mode, SEN, SDATA, and SCLK function as serial interface pins and are
used to access the internal registers of ADC. The registers are reset either by applying a pulse on the RESET
pin, or by a high setting on the <RST> bit (D1 in register 0x6C). The serial interface section describes the
register programming and register reset in more detail.
Since the parallel pins DFS and MODE are not used in this mode, they must be tied to ground.
USING BOTH THE SERIAL INTERFACE AND PARALLEL CONTROLS
For increased flexibility, a combination of serial interface registers and parallel pin controls (DFS, MODE) can
also be used to configure the device.
The serial registers must first be reset to their default values and the RESET pin must be kept low. In this mode,
SEN, SDATA, and SCLK function as serial interface pins and are used to access the internal registers of ADC.
The registers are reset either by applying a pulse on RESET pin or by a high setting on the <RST> bit (D1 in
register 0x6C). The serial interface section describes the register programming and register reset in more detail.
The parallel interface control pins DFS and MODE are used and their function is determined by the appropriate
voltage levels as described in Table 6 and Table 7. The voltage levels are derived by using a resistor string as
illustrated in Figure 4. Since some functions are controlled using both the parallel pins and serial registers, the
priority between the two is determined by a priority table (Table 2).
Submit Documentation Feedback
11
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
Table 2. Priority Between Parallel Pins and Serial Registers
PIN
MODE
FUNCTIONS SUPPORTED
PRIORITY
Internal/External reference
When using the serial interface, bit <REF> (register 0x6D, bit D4) controls this mode, ONLY
if the MODE pin is tied low.
DATA FORMAT
When using the serial interface, bit <DF> (register 0x63, bit D3) controls this mode, ONLY if
the DFS pin is tied low.
LVDS/CMOS
When using the serial interface, bit <ODI> (register 0x6C, bits D3-D4) controls LVDS/CMOS
selection independent of the state of DFS pin
DFS
AVDD
(2/3) AVDD
R
(2/3) AVDD
GND
R
AVDD
(1/3) AVDD
(1/3) AVDD
R
To Parallel Pin
Figure 4. Simple Scheme to Configure Parallel Pins
12
Submit Documentation Feedback
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
DESCRIPTION OF PARALLEL PINS
Table 3. SCLK Control Pin
SCLK (Pin 29)
DESCRIPTION
0
LOW SPEED mode Disabled - Use for sampling frequencies above 50 MSPS.
DRVDD
LOW SPEED mode Enabled - Use for sampling frequencies below 50 MSPS.
Table 4. SDATA Control Pin
SDATA (Pin 28)
0
DRVDD
DESCRIPTION
Normal operation (Default)
STANDBY. This is a global power down, where ADC, internal references and the output buffers are powered down.
Table 5. SEN Control Pin
SEN (Pin 27)
0
(1);
LVDS mode: CLKOUT edge aligned with data transition
(1/3)DRVDD
CMOS mode: CLKOUT edge later by (2/12)Ts ; LVDS mode: CLKOUT edge aligned with data transition
(2/3)DRVDD
CMOS mode: CLKOUT edge later by (1/12)Ts ; LVDS mode: CLKOUT edge earlier by (1/12)Ts
DRVDD
(1)
DESCRIPTION
CMOS mode: CLKOUT edge later by (3/12)Ts
Default CLKOUT position
Ts = 1/Sampling Frequency
Table 6. DFS Control Pin
DFS (Pin 6)
0
DESCRIPTION
2's complement data and DDR LVDS output (Default)
(1/3)DRVDD
2's complement data and parallel CMOS output
(2/3)DRVDD
Offset binary data and parallel CMOS output
DRVDD
Offset binary data and DDR LVDS output
Table 7. MODE Control Pin
MODE (Pin 23)
DESCRIPTION
0
Internal reference
(1/3)AVDD
External reference
(2/3)AVDD
External reference
AVDD
Internal reference
SERIAL INTERFACE
The ADC has a set of internal registers, which can be accessed through the serial interface formed by pins SEN
(Serial interface Enable), SCLK (Serial Interface Clock), SDATA (Serial Interface Data) and RESET. After device
power-up, the internal registers must be reset to their default values by applying a high-going pulse on RESET
(of width greater than 10 ns).
Serial shift of bits into the device is enabled when SEN is low. Serial data SDATA is latched at every falling edge
of SCLK when SEN is active (low). The serial data is loaded into the register at every 16th SCLK falling edge
when SEN is low. If the word length exceeds a multiple of 16 bits, the excess bits are ignored. Data is loaded in
multiples of 16-bit words within a single active SEN pulse.
The first 8 bits form the register address and the remaining 8 bits form the register data.
Submit Documentation Feedback
13
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
REGISTER INITIALIZATION
After power-up, the internal registers must be reset to their default values. This is done in one of two ways:
1. Either through hardware reset by applying a high-going pulse on RESET pin (of width greater than 10 ns) as
shown in Figure 5.
OR
2. By applying software reset. Using the serial interface, set the <RST> bit (D1 in register 0x6C) to high. This
initializes the internal registers to their default values and then self-resets the <RST> bit to low. In this case
the RESET pin is kept low.
Register Address
SDATA
A7
A6
A5
A4
A3
A2
Register Data
A1
A0
D7
t(SCLK)
D6
D5
D4
D3
D2
D1
D0
t(DH)
t(DSU)
SCLK
t(SLOADH)
t(SLOADS)
SEN
RESET
Figure 5. Serial Interface Timing Diagram
SERIAL INTERFACE TIMING CHARACTERISTICS
Typical values at 25°C, min and max values across the full temperature range TMIN = –40°C to TMAX = 85°C,
AVDD = DRVDD = 3.3 V (unless otherwise noted)
MIN
tSCLK
SCLK period
TYP
50
SCLK duty cycle
MAX
UNIT
ns
50%
tSLOADS
SEN to SCLK setup time
25
ns
tSLOADH
SCLK to SEN hold time
25
ns
tDSU
SDATA setup time
25
ns
tDH
SDATA hold time
25
ns
14
Submit Documentation Feedback
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
RESET TIMING
Typical values at 25°C, min and max values across the full temperature range TMIN = –40°C to TMAX = 85°C,
AVDD = DRVDD = 3.3 V (unless otherwise noted)
PARAMETER
TEST CONDITIONS
t1
Power-on delay
Delay from power-up of AVDD and DRVDD to RESET pulse active
MIN
t2
Reset pulse width
t3
tPO
TYP
MAX
UNIT
5
ms
Pulse width of active RESET signal
10
ns
Register write delay
Delay from RESET disable to SEN active
25
ns
Power-up time
Delay from power-up of AVDD and DRVDD to output stable
6.5
ms
Power Supply
AVDD, DRVDD
t1
RESET
t2
t3
SEN
NOTE: A high-going pulse on RESET pin is required in serial interface mode in case of initialization through hardware reset.
For parallel interface operation, RESET has to be tied permanently HIGH.
Figure 6. Reset Timing Diagram
Submit Documentation Feedback
15
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
DESCRIPTION OF SERIAL REGISTERS
Table 8 gives a summary of all the modes that can be programmed through the serial interface.
Table 8. Serial Interface Register Map
REGISTER ADDRESS
A7
A6
A5
A4
A3
A2
REGISTER DATA
A1
A0
D7
D6
D5
D4
D3
D2
D1
DESCRIPTION
D0
<STBY> – Global Power Down
0
1
1
0
0
0
1
1
0
0
0
1
1
0
0
0
1
1
1
0
0
0
0
0
0
0
NORMAL converter operation (Default after
reset)
0
0
0
0
0
0
STANDBY
1
0
Resets all registers to default values
<RST> – Software Reset
0
1
1
0
1
1
0
0
0
0
0
0
0
0
<DF> – Output Data Format
0
1
1
0
0
0
1
1
0
0
0
0
0
0
0
0
2's complement output format (Default after
reset)
0
1
1
0
0
0
1
1
0
0
0
0
1
0
0
0
Straight binary output format
<ODI> – Output Data Interface
0
1
1
0
1
1
0
0
0
0
0
0
1
0
0
0
DDR LVDS outputs (D4:D3 defaults to 00
after reset)
0
1
1
0
1
1
0
0
0
0
0
1
1
0
0
0
Parallel CMOS outputs
<REF> –Internal/External reference mode
0
1
1
0
1
1
0
1
0
0
0
0
0
0
0
0
Internal reference (Default after reset)
0
1
1
0
1
1
0
1
0
0
0
1
0
0
0
0
External reference – Force voltage on VCM
pin
0
1
1
0
0
1
0
1
0
0
0
0
0
0
0
0
Normal operation (Default after reset)
0
1
1
0
0
1
0
1
0
0
1
0
0
0
0
0
All zeros
0
1
1
0
0
1
0
1
0
1
0
0
0
0
0
0
All ones
0
1
1
0
0
1
0
1
0
1
1
0
0
0
0
0
Toggle pattern Alternate 1s and 0s on each
data output and across the data outputs.
0
1
1
0
0
1
0
1
1
0
0
0
0
0
0
0
Ramp pattern – Output data ramps from
0x0000 to 0x3FFF every clock cycle
0
1
1
0
0
1
0
1
1
0
1
0
0
0
0
0
Custom pattern. Write the custom pattern in
CUSTOM PATTERN registers A and B.
0
1
1
0
0
1
0
1
X
X
X
0
0
0
0
0
NOT USED
<TEST PATTERN> – Output test pattern on data outputs
<CUSTOM PATTERN> – Output custom pattern on data outputs
0
1
1
0
1
0
0
1
D7
D6
D5
D4
D3
D2
D1
D0 CUSTOM PATTERN D7-D0
0
1
1
0
1
0
1
0
0
0
D13
D12
D11
D10
D9
D8 CUSTOM PATTERN D13-D8
<CLK GAIN> – Clock Buffer gain programmability, Gain decreases monotonically from Gain 4 to Gain 0
0
1
1
0
1
0
1
1
0
0
1
1
0
0
1
0
Gain 4
0
1
1
0
1
0
1
1
0
0
1
0
1
0
1
0
Gain 3
0
1
1
0
1
0
1
1
0
0
1
0
0
1
1
0
Gain 2
0
1
1
0
1
0
1
1
0
0
1
0
0
0
0
0
Gain 1 (Default after reset)
0
1
1
0
1
0
1
1
0
0
1
0
0
0
1
1
Gain 0 Minimum gain
<POWER SCALING> Power scaling vs sampling frequency. The ADC can be operated at reduced power at lower sampling rates
with no loss in performance.
16
0
1
1
0
1
1
0
1
0
0
1
0
0
0
0
0
Default Fs > 150 MSPS (Default after reset)
0
1
1
0
1
1
0
1
1
0
1
0
0
0
0
0
Power Mode 1 – 105 < Fs ≤ 150 MSPS
0
1
1
0
1
1
0
1
0
1
1
0
0
0
0
0
Power Mode 2 – 50 < Fs ≤ 105 MSPS
0
1
1
0
1
1
0
1
1
1
1
0
0
0
0
0
Power Mode 3 – Fs ≤ 50 MSPS
Submit Documentation Feedback
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
Table 8. Serial Interface Register Map (continued)
REGISTER ADDRESS
A7
A6
A5
A4
A3
A2
REGISTER DATA
A1
A0
D7
D6
D5
D4
D3
D2
D1
DESCRIPTION
D0
<GAIN> Gain programming - Channel gain can be programmed from 0 to 6 dB for SFDR/SNR trade-off. For each gain setting, the
input full-scale range has to be proportionally scaled. For 6 dB gain, the full-scale range is 1 VPP compared to 2 VPP at 0 dB gain.
0
1
1
0
1
0
0
0
0
0
0
0
1
0
0
0
0 dB (Default after reset)
0
1
1
0
1
0
0
0
0
0
0
0
1
0
0
1
1 dB
0
1
1
0
1
0
0
0
0
0
0
0
1
0
1
0
2 dB
0
1
1
0
1
0
0
0
0
0
0
0
1
0
1
1
3 dB
0
1
1
0
1
0
0
0
0
0
0
0
1
1
0
0
4 dB
0
1
1
0
1
0
0
0
0
0
0
0
1
1
0
1
5 dB
0
1
1
0
1
0
0
0
0
0
0
0
1
1
1
0
6 dB
0
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
3.5 mA (Default after reset)
0
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
2.5 mA
0
1
1
1
1
1
1
0
0
0
0
0
0
0
1
0
4.5 mA
0
1
1
1
1
1
1
0
0
0
0
0
0
0
1
1
1.75 mA
<LVDS CURRENT> – LVDS Output data and clock buffers nominal current programmability
<CURRENT DOUBLE> – The output data and clock buffer currents are doubled from the value selected by the <LVDS CURRENT>
register.
0
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
value specified by <LVDS CURRENT>
(Default after reset)
0
1
1
1
1
1
1
1
0
1
0
0
0
0
0
0
2x data, 2x clock currents
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
1x data, 2x clock currents
0
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
2x data, 4x clock currents
<DATA TERM> Internal termination - Option to terminate the LVDS DATA buffers inside the ADC to improve signal integrity. By
default, internal termination is disabled.
0
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
No termination (Default after reset)
0
1
1
1
1
1
1
0
0
0
1
0
0
0
0
0
325 Ω
0
1
1
1
1
1
1
0
0
1
0
0
0
0
0
0
200 Ω
0
1
1
1
1
1
1
0
0
1
1
0
0
0
0
0
125 Ω
0
1
1
1
1
1
1
0
1
0
0
0
0
0
0
0
170 Ω
0
1
1
1
1
1
1
0
1
0
1
0
0
0
0
0
120 Ω
0
1
1
1
1
1
1
0
1
1
0
0
0
0
0
0
100 Ω
0
1
1
1
1
1
1
0
1
1
1
0
0
0
0
0
75 Ω
<CLK TERM> Internal termination - Option to terminate the LVDS CLK buffers inside the ADC to improve signal integrity. By
default, internal termination is disabled.
0
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
No termination (Default after reset)
0
1
1
1
1
1
1
0
0
0
0
0
0
1
0
0
325 Ω
0
1
1
1
1
1
1
0
0
0
0
0
1
0
0
0
200 Ω
0
1
1
1
1
1
1
0
0
0
0
0
1
1
0
0
125 Ω
0
1
1
1
1
1
1
0
0
0
0
1
0
0
0
0
170 Ω
0
1
1
1
1
1
1
0
0
0
0
1
0
1
0
0
120 Ω
0
1
1
1
1
1
1
0
0
0
0
1
1
0
0
0
100 Ω
0
1
1
1
1
1
1
0
0
0
0
1
1
1
0
0
75 Ω
<CLKOUT POSN CMOS> – Output clock rising edge programmability in CMOS mode
(1)
(1)
0
1
1
0
0
0
1
0
0
0
0
0
0
0
0
1
Default position
0
1
1
0
0
0
1
0
0
0
0
0
0
0
1
1
CLKOUT rising edge later by (1/12)Ts
0
1
1
0
0
0
1
0
0
0
0
0
0
1
0
1
CLKOUT rising edge later by (3/12)Ts
0
1
1
0
0
0
1
0
0
0
0
0
0
1
1
1
CLKOUT rising edge later by (2/12)Ts
Ts = 1/Sampling Frequency
Submit Documentation Feedback
17
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
Table 8. Serial Interface Register Map (continued)
REGISTER ADDRESS
A7
A6
A5
A4
A3
A2
REGISTER DATA
A1
A0
D7
D6
D5
D4
D3
D2
D1
DESCRIPTION
D0
<CLKOUT POSN CMOS> – Output clock falling edge programmability in CMOS mode
(2)
0
1
1
0
0
0
1
0
0
0
0
0
0
0
0
1
Default position
0
1
1
0
0
0
1
0
0
0
0
0
1
0
0
1
CLKOUT falling edge later by (1/12)Ts
0
1
1
0
0
0
1
0
0
0
0
1
0
0
0
1
CLKOUT falling edge later by (3/12)Ts
0
1
1
0
0
0
1
0
0
0
0
1
1
0
0
1
CLKOUT falling edge later by (2/12)Ts
<CLKOUT POSN LVDS> – Output clock rising edge programmability in LVDS mode
(2)
0
1
1
0
0
0
1
0
0
0
0
0
0
0
0
1
Default position
0
1
1
0
0
0
1
0
0
0
0
0
0
0
1
1
CLKOUT rising edge earlier by (1/12)Ts
0
1
1
0
0
0
1
0
0
0
0
0
0
1
0
1
CLKOUT rising edge aligned with data
transition
0
1
1
0
0
0
1
0
0
0
0
0
0
1
1
1
CLKOUT rising edge aligned with data
transition
<CLKOUT POSN LVDS> – Output clock falling edge programmability in LVDS mode
(2)
0
1
1
0
0
0
1
0
0
0
0
0
0
0
0
1
Default position
0
1
1
0
0
0
1
0
0
0
0
0
1
0
0
1
CLKOUT falling edge earlier by (1/12)Ts
0
1
1
0
0
0
1
0
0
0
0
1
0
0
0
1
CLKOUT falling edge aligned with data
transition
0
1
1
0
0
0
1
0
0
0
0
1
1
0
0
1
CLKOUT falling edge aligned with data
transition
<LOW SPEED> – For low sampling frequency operation
(2)
18
0
1
1
0
0
0
1
1
0
0
0
0
0
0
0
0
DEFAULT SPEED mode - for 50 < Fs ≤ 210
MSPS
0
1
1
0
0
0
1
1
0
0
0
1
0
0
0
0
LOW SPEED mode - for 1 < Fs ≤ 50 MSPS
Ts = 1/Sampling Frequency
Submit Documentation Feedback
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
PIN CONFIGURATION (LVDS MODE)
37 D2_D3_M
38 D2_D3_P
39 D4_D5_M
40 D4_D5_P
41 D6_D7_M
42 D6_D7_P
43 D8_D9_M
44 D8_D9_P
45 D10_D11_M
46 D10_D11_P
47 D12_D13_M
48 D12_D13_P
RGZ PACKAGE
(TOP VIEW)
DRGND 1
36 DRGND
DRVDD 2
35 DRVDD
OVR 3
34 D0_D1_P
CLKOUTM 4
33 D0_D1_M
CLKOUTP 5
32 NC
DFS 6
31 NC
OE 7
30 RESET
AVDD 8
29 SCLK
AGND 9
28 SDATA
AVDD 24
MODE 23
AVDD 22
IREF 21
AVDD 20
AGND 19
AVDD 18
25 AGND
AGND 17
AGND 12
INM 16
26 AVDD
INP 15
CLKM 11
AGND 14
27 SEN
VCM 13
CLKP 10
Figure 7. LVDS Mode Pinout
PIN ASSIGNMENTS – LVDS Mode
PIN NAME
DESCRIPTION
PIN
TYPE
PIN
NUMBER
NUMBER
OF PINS
AVDD
Analog power supply
I
8, 18, 20,
22, 24, 26
6
AGND
Analog ground
I
9, 12, 14,
17, 19, 25
6
CLKP, CLKM
Differential clock input
I
10, 11
2
INP, INM
Differential analog input
I
15, 16
2
VCM
Internal reference mode – Common-mode voltage output.
External reference mode – Reference input. The voltage forced on this pin sets
the internal references.
I/O
13
1
IREF
Current-set resistor, 56.2-kΩ resistor to ground.
I
21
1
RESET
Serial interface RESET input.
When using the serial interface mode, the user MUST initialize internal registers
through hardware RESET by applying a high-going pulse on this pin, or by using
the software reset option. See the SERIAL INTERFACE section.
In parallel interface mode, the user has to tie the RESET pin permanently HIGH.
(SDATA and SEN are used as parallel pin controls in this mode)
The pin has an internal 100-kΩ pull-down resistor.
I
30
1
Submit Documentation Feedback
19
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
PIN CONFIGURATION (LVDS MODE) (continued)
PIN ASSIGNMENTS – LVDS Mode (continued)
PIN
TYPE
PIN
NUMBER
NUMBER
OF PINS
I
29
1
I
28
1
SEN
This pin functions as serial interface enable input when RESET is low. It functions
as CLKOUT edge programmability when RESET is tied high. See Table 5 for
detailed information.
The pin has an internal 100-kΩ pull-up resistor to DRVDD.
I
27
1
OE
Output buffer enable input, active high. The pin has an internal 100-kΩ pull-up
resistor to DRVDD.
I
7
1
DFS
Data Format Select input. This pin sets the DATA FORMAT (Twos complement or
Offset binary) and the LVDS/CMOS output mode type. See Table 6 for detailed
information.
I
6
1
MODE
Mode select input. This pin selects the Internal or External reference mode. See
Table 7 for detailed information.
I
23
1
CLKOUTP
Differential output clock, true
O
5
1
CLKOUTM
Differential output clock, complement
O
4
1
D0_D1_P
Differential output data D0 and D1 multiplexed, true
O
34
1
D0_D1_M
Differential output data D0 and D1 multiplexed, complement.
O
33
1
D2_D3_P
Differential output data D2 and D3 multiplexed, true
O
38
1
D2_D3_M
Differential output data D2 and D3 multiplexed, complement
O
37
1
D4_D5_P
Differential output data D4 and D5 multiplexed, true
O
40
1
D4_D5_M
Differential output data D4 and D5 multiplexed, complement
O
39
1
D6_D7_P
Differential output data D6 and D7 multiplexed, true
O
42
1
D6_D7_M
Differential output data D6 and D7 multiplexed, complement
O
41
1
D8_D9_P
Differential output data D8 and D9 multiplexed, true
O
44
1
D8_D9_M
Differential output data D8 and D9 multiplexed, complement
O
43
1
D10_D11_P
Differential output data D10 and D11 multiplexed, true
O
46
1
D10_D11_M
Differential output data D10 and D11 multiplexed, complement
O
45
1
D12_D13_P
Differential output data D12 and D13 multiplexed, true
O
48
1
D12_D13_M
Differential output data D12 and D13 multiplexed, complement
O
47
1
OVR
Out-of-range indicator, CMOS level signal
O
3
1
DRVDD
Digital and output buffer supply
I
2, 35
2
DRGND
Digital and output buffer ground
I
1, 36
2
NC
Do not connect
31, 32
2
PIN NAME
SCLK
DESCRIPTION
This pin functions as serial interface clock input when RESET is low.
It functions as LOW SPEED control pin when RESET is tied high. Tie SCLK to
LOW for Fs > 50 MSPS and SCLK to HIGH for Fs ≤ 50 MSPS. See Table 3.
The pin has an internal 100-kΩ pull-down resistor.
This pin functions as serial interface data input when RESET is low. It functions
as STANDBY control pin when RESET is tied high.
SDATA
See Table 4 for detailed information.
The pin has an internal 100 kΩ pull-down resistor.
20
Submit Documentation Feedback
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
PIN CONFIGURATION (CMOS MODE)
37 D2
38 D3
39 D4
40 D5
41 D6
42 D7
43 D8
44 D9
45 D10
46 D11
47 D12
48 D13
RGZ PACKAGE
(TOP VIEW)
DRGND 1
36 DRGND
DRVDD 2
35 DRVDD
OVR 3
34 D1
UNUSED 4
33 D0
CLKOUT 5
32 NC
DFS 6
31 NC
OE 7
30 RESET
AVDD 8
29 SCLK
AGND 9
28 SDATA
AVDD 24
MODE 23
AVDD 22
IREF 21
AVDD 20
AGND 19
AVDD 18
25 AGND
AGND 17
AGND 12
INM 16
26 AVDD
INP 15
CLKM 11
AGND 14
27 SEN
VCM 13
CLKP 10
Figure 8. CMOS Mode Pinout
PIN ASSIGNMENTS – CMOS Mode
PIN NAME
DESCRIPTION
PIN
TYPE
PIN
NUMBER
NUMBER
OF PINS
AVDD
Analog power supply
I
8, 18, 20,
22, 24, 26
6
AGND
Analog ground
I
9, 12, 14, 17,
19, 25
6
CLKP, CLKM Differential clock input
I
10, 11
2
INP, INM
Differential analog input
I
15, 16
2
VCM
Internal reference mode – Common-mode voltage output.
External reference mode – Reference input. The voltage forced on this pin sets
the internal references.
I/O
13
1
IREF
Current-set resistor, 56.2-kΩ resistor to ground.
I
21
1
I
30
1
I
29
1
Serial interface RESET input.
RESET
When using the serial interface mode, the user MUST initialize internal registers
through hardware RESET by applying a high-going pulse on this pin, or by using
the software reset option. See the SERIAL INTERFACE section.
In parallel interface mode, the user has to tie RESET pin permanently HIGH.
(SDATA and SEN are used as parallel pin controls in this mode).
The pin has an internal 100-kΩ pull-down resistor.
SCLK
This pin functions as serial interface clock input when RESET is low.
It functions as LOW SPEED control pin when RESET is tied high. Tie SCLK to
LOW for Fs > 50 MSPS and SCLK to HIGH for Fs ≤ 50 MSPS. See Table 3.
The pin has an internal 100-kΩ pull-down resistor.
Submit Documentation Feedback
21
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
PIN CONFIGURATION (CMOS MODE) (continued)
PIN ASSIGNMENTS – CMOS Mode (continued)
PIN NAME
DESCRIPTION
PIN
TYPE
PIN
NUMBER
NUMBER
OF PINS
I
28
1
I
27
1
This pin functions as serial interface data input when RESET is low. It functions as
STANDBY control pin when RESET is tied high.
SDATA
See Table 4 for detailed information.
The pin has an internal 100 kΩ pull-down resistor.
SEN
This pin functions as serial interface enable input when RESET is low. It functions
as CLKOUT edge programmability when RESET is tied high. See Table 5 for
detailed information.
The pin has an internal 100-kΩ pull-up resistor to DRVDD.
OE
Output buffer enable input, active high. The pin has an internal 100-kΩ pull-up
resistor to DRVDD.
I
7
1
DFS
Data Format Select input. This pin sets the DATA FORMAT (Twos complement or
Offset binary) and the LVDS/CMOS output mode type. See Table 6 for detailed
information.
I
6
1
MODE
Mode select input. This pin selects the internal or external reference mode. See
Table 7 for detailed information.
I
23
1
CLKOUT
CMOS output clock
O
5
1
D0
CMOS output data D0
O
33
1
D0
CMOS output data D1
O
34
1
D2
CMOS output data D2
O
37
1
D2
CMOS output data D3
O
38
1
D4
CMOS output data D4
O
39
1
D4
CMOS output data D5
O
40
1
D6
CMOS output data D6
O
41
1
D7
CMOS output data D7
O
42
1
D8
CMOS output data D8
O
43
1
D9
CMOS output data D9
O
44
1
D10
CMOS output data D10
O
45
1
D11
CMOS output data D11
O
46
1
D12
CMOS output data D12
O
47
1
D13
CMOS output data D13
O
48
1
OVR
Out-of-range indicator, CMOS level signal
O
3
1
DRVDD
Digital and output buffer supply
I
2, 35
2
DRGND
Digital and output buffer ground
I
1, 36
2
UNUSED
Unused pin in CMOS mode
4
1
NC
Do not connect
31, 32
2
22
Submit Documentation Feedback
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
TYPICAL CHARACTERISTICS
All plots are at 25°C, AVDD = DRVDD = 3.3 V, sampling frequency = 210 MSPS, sine wave input clock, 1.5 VPP differential
clock amplitude, 50% clock duty cycle, –1 dBFS differential analog input, internal reference mode, 0 dB gain, DDR LVDS
data output (unless otherwise noted)
FFT for 20 MHz INPUT SIGNAL
FFT for 70 MHz INPUT SIGNAL
Figure 9.
Figure 10.
FFT for 100 MHz INPUT SIGNAL
FFT for 170 MHz INPUT SIGNAL
0
0
SFDR = 81.74 dBc,
SNR = 72.46 dBFS,
SINAD = 71.37 dBFS
-40
SFDR = 82.82 dBc,
SNR = 71.6 dBFS,
SINAD = 70.83 dBFS
-20
Amplitude - dB
Amplitude - dB
-20
-60
-80
-100
-120
-40
-60
-80
-100
-120
-140
-140
0
10
20
30
40
50
60
70
80
90
100
0
10
20
30
f - Frequency - MHz
50
60
70
80
90
100
90
100
f - Frequency - MHz
Figure 11.
Figure 12.
FFT for 220 MHz INPUT SIGNAL
FFT for 300 MHz INPUT SIGNAL
0
0
SFDR = 80.98 dBc,
SNR = 70.86 dBFS,
SINAD = 70.16 dBFS
-20
-40
-60
-80
-100
-120
SFDR = 74.68 dBc,
SNR = 69.48 dBFS,
SINAD = 67.47 dBFS
-20
Amplitude - dB
Amplitude - dB
40
-40
-60
-80
-100
-120
-140
-140
0
10
20
30
40
50
60
70
80
90
100
0
10
f - Frequency - MHz
20
30
40
50
60
70
80
f - Frequency - MHz
Figure 13.
Figure 14.
Submit Documentation Feedback
23
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
TYPICAL CHARACTERISTICS (continued)
All plots are at 25°C, AVDD = DRVDD = 3.3 V, sampling frequency = 210 MSPS, sine wave input clock, 1.5 VPP differential
clock amplitude, 50% clock duty cycle, –1 dBFS differential analog input, internal reference mode, 0 dB gain, DDR LVDS
data output (unless otherwise noted)
FFT for 400 MHz INPUT SIGNAL
FFT for 600 MHz INPUT SIGNAL
0
0
SFDR = 70.92 dBc,
SNR = 68.19 dBFS,
SINAD = 64.82 dBFS
SFDR = 65.5 dBc,
SNR = 65.29 dBFS,
SINAD = 61 dBFS
-20
-40
Amplitude - dB
Amplitude - dB
-20
-60
-80
-100
-120
-40
-60
-80
-100
-120
-140
-140
0
10
20
30
40
50
60
70
80
90
100
0
10
20
30
f - Frequency - MHz
70
80
100
90
Figure 16.
INTERMODULATION DISTORTION (IMD) vs FREQUENCY
INTERMODULATION DISTORTION (IMD) vs FREQUENCY
0
fIN1 = 50.03 MHz, -7 dBFS,
fIN2 = 46.03 MHz, -7 dBFS,
SFDR = 88.5 dBc,
2-Tone IMD, 91.1 dBFS
-40
fIN1 = 190.1 MHz, -7 dBFS,
fIN2 = 185.02 MHz, -7 dBFS,
SFDR = 87.1 dBc,
2-Tone IMD, 86.5 dBFS
-20
Amplitude - dB
Amplitude - dB
60
Figure 15.
-20
-60
-80
-100
-120
-40
-60
-80
-100
-120
-140
-140
0
10
20
30
40
50
60
70
80
90
100
0
10
20
30
f - Frequency - MHz
40
50
60
70
80
90
100
f - Frequency - MHz
Figure 17.
Figure 18.
SFDR vs INPUT FREQUENCY
SNR vs INPUT FREQUENCY
75
90
74
SNR − dBFS
86
82
SFDR - dBc
50
f - Frequency - MHz
0
78
74
LVDS Mode
73
72
71
70
69
70
68
66
67
62
66
0
50
100
150
200
250
300
350
400
0
fIN - Input Frequency - MHz
Figure 19.
24
40
50
100
150
200
250
Figure 20.
Submit Documentation Feedback
300
fIN − Input Frequency − MHz
350
400
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
TYPICAL CHARACTERISTICS (continued)
All plots are at 25°C, AVDD = DRVDD = 3.3 V, sampling frequency = 210 MSPS, sine wave input clock, 1.5 VPP differential
clock amplitude, 50% clock duty cycle, –1 dBFS differential analog input, internal reference mode, 0 dB gain, DDR LVDS
data output (unless otherwise noted)
SNR vs INPUT FREQUENCY
SFDR vs GAIN
75
96
74
CMOS Mode
1 dB
2 dB
3 dB
92
88
72
SFDR − dBc
SNR - dBFS
73
71
70
69
84
80
68
76
67
72
6 dB
5 dB 4 dB
0 dB
66
0
50
100
150
200
250
68
300
0
50
fIN - Input Frequency - MHz
100
150
200
250
300
350
400
fIN − Input Frequency − MHz
Figure 21.
Figure 22.
SNR vs GAIN
PERFORMANCE vs AVDD
76
92
75
90
74.5
1 dB
2 dB
3 dB
SFDR - dBc
SNR − dBFS
74
72
70
68
74
FIN = 70 MHz
DRVDD = 3.3 V
73.5
86
SNR
73
84
5 dB
66
4 dB
82
3
6 dB
64
SFDR
88
0
50
100
SNR - dBFS
0 dB
150
200
250
300
350
72.5
3.1
3.2
3.3
3.4
3.5
3.6
AVDD - Supply Voltage - V
400
fIN − Input Frequency − MHz
Figure 23.
Figure 24.
PERFORMANCE vs DRVDD
PERFORMANCE vs TEMPERATURE
75
92
75.0
fIN = 70 MHz
74.5
73.5
86
SNR
73
84
SFDR − dBc
74
SNR − dBFS
fIN = 70 MHz
AVDD = 3.3 V
88
74.5
90
SFDR
88
74.0
86
73.5
84
SNR − dBFS
SFDR
90
SFDR − dBc
92
73.0
SNR
72.5
82
3.0
3.1
3.2
3.3
3.4
3.5
3.6
82
−40
−15
10
50
35
72.5
85
o
TA − Free-Air Temperature − C
DRVDD − Supply Voltage − V
Figure 25.
Figure 26.
Submit Documentation Feedback
25
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
TYPICAL CHARACTERISTICS (continued)
All plots are at 25°C, AVDD = DRVDD = 3.3 V, sampling frequency = 210 MSPS, sine wave input clock, 1.5 VPP differential
clock amplitude, 50% clock duty cycle, –1 dBFS differential analog input, internal reference mode, 0 dB gain, DDR LVDS
data output (unless otherwise noted)
SNR vs SAMPLING FREQUENCY
ACROSS POWER SCALING MODES
75
POWER DISSIPATION vs
SAMPLING FREQUENCY
1.24
PD − Power Dissipation − W
fIN = 70 MHz
74
72
Default
71
Power Mode 1
70
Power Mode 3
69
68
Power Mode 2
67
66
40
60
80
100
120
140
160
180
1.12
1.00
0.94
0.88
Power Mode 1
0.82
0.76
0.70
0.64
220
200
Default
1.06
Power Mode 2
Power Mode 3
0
20
40
60
80 100 120 140 160 180 200 220
FS − Sampling Frequency − MSPS
FS − Sampling Frequency − MSPS
Figure 27.
Figure 28.
PERFORMANCE vs INPUT AMPLITUDE
PERFORMANCE vs CLOCK AMPLITUDE
105
95
76
75
74
SNR (dBFS)
65
73.5
55
73
SFDR (dBc)
SFDR
84
74
SNR
73
82
72.5
80
71.5
−40
−30
−20
−10
78
0.3
0
0.5
0.8
1.5
1.8
2.1
2.5
Figure 30.
PERFORMANCE vs INPUT CLOCK DUTY CYCLE
OUTPUT NOISE HISTOGRAM WITH
INPUTS TIED TO COMMON-MODE
35
78
72
45
50
55
Input Clock Duty Cycle − %
60
65
15
10
5
0
Output Code
Figure 31.
Figure 32.
Submit Documentation Feedback
8250
73
8249
80
8248
SNR
20
8246
74
25
8245
82
30
8243
75
8242
84
Occurence − %
SFDR
SNR − dBFS
76
86
40
71
2.8
40
77
fIN = 10 MHz
26
2.3
Figure 29.
88
SFDR − dBc
1.3
Clock Amplitude - VPP
Input Amplitude − dBFS
35
1.1
8252
−50
8244
25
−60
fIN = 70 MHz
72
fIN = 70 MHz
Sine Wave Input Clock
72
35
8251
45
SFDR - dBc
75
75
86
74.5
SNR - dBFS
SFDR (dBFS)
85
SNR − dBFS
SFDR − dBc, dBFS
88
75.5
8247
SNR − dBFS
73
LVDS Mode
1.18
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
TYPICAL CHARACTERISTICS (continued)
All plots are at 25°C, AVDD = DRVDD = 3.3 V, sampling frequency = 210 MSPS, sine wave input clock, 1.5 VPP differential
clock amplitude, 50% clock duty cycle, –1 dBFS differential analog input, internal reference mode, 0 dB gain, DDR LVDS
data output (unless otherwise noted)
PERFORMANCE IN EXTERNAL REFERENCE MODE
88
-35
76
-40
84
74
82
73
SNR
80
72
CMRR − dBc
SFDR
SNR − dBFS
75
86
SFDR − dBc
COMMON-MODE REJECTION RATIO vs FREQUENCY
-45
-50
-55
-60
-65
78
1.4
71
1.45
1.5
1.55
Voltage Forced on the CM Pin − V
1.6
-70
0
20
40
60
80
100
f - Frequency of AC Common-Mode Voltage - MHz
Figure 33.
Figure 34.
Submit Documentation Feedback
27
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
TYPICAL CHARACTERISTICS (continued)
All plots are at 25°C, AVDD = DRVDD = 3.3 V, sampling frequency = 210 MSPS, sine wave input clock, 1.5 VPP differential
clock amplitude, 50% clock duty cycle, –1 dBFS differential analog input, internal reference mode, 0 dB gain, DDR LVDS
data output (unless otherwise noted)
fS - Sampling Frequency - MSPS
210
200
180
160
140
120
100
80
65
100
200
300
400
500
600
700
fIN - Input Frequency - MHz
62
63
64
65
66
67
68
69
70
71
72
73
SNR - dBFS
Figure 35. SNR Contour in dBFS
fS - Sampling Frequency - MSPS
210
200
180
160
140
120
100
80
65
100
200
300
400
500
600
700
80
85
90
fIN - Input Frequency - MHz
55
60
65
70
75
SFDR - dBc
Figure 36. SFDR Contour in dBc
28
Submit Documentation Feedback
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
APPLICATION INFORMATION
THEORY OF OPERATION
ADS5547 is a low power 14-bit 210 MSPS pipeline ADC in a CMOS process. ADS5547 is based on switched
capacitor technology and runs off a single 3.3-V supply. The conversion process is initiated by a rising edge of
the external input clock. Once the signal is captured by the input sample and hold, the input sample is
sequentially converted by a series of lower resolution stages, with the outputs combined in a digital correction
logic block. At every clock edge, the sample propagates through the pipeline resulting in a data latency of 14
clock cycles. The output is available as 14-bit data, in DDR LVDS or CMOS and coded in either straight offset
binary or binary 2’s complement format.
ANALOG INPUT
The analog input consists of a switched-capacitor based differential sample and hold architecture, shown in
Figure 37.
This differential topology results in good ac-performance even for high input frequencies at high sampling rates.
The INP and INM pins have to be externally biased around a common-mode voltage of 1.5 V available on VCM
pin 13. For a full-scale differential input, each input pin INP, INM has to swing symmetrically between VCM +
0.5 V and VCM – 0.5 V, resulting in a 2-VPP differential input swing. The maximum swing is determined by the
internal reference voltages REFP (2.5 V nominal) and REFM (0.5 V, nominal).
Sampling
Switch
Lpkg
6 nH
Sampling
Capacitor
R-C-R Filter
INP
Cbond
2 pF
10 W
50 W
Resr
200 W
1.6 pF
Lpkg
6 nH
Cpar2
1 pF
Ron
15 W
Ron
10 W
Cpar1
0.8 pF
50 W
Ron
15 W
10 W
Csamp
2.4 pF
Csamp
2.4 pF
INM
Cbond
2 pF
Resr
200 W
Sampling
Capacitor
Cpar2
1 pF
Sampling
Switch
Figure 37. Input Stage
The input sampling circuit has a high 3-dB bandwidth that extends up to 800 MHz (measured from the input pins
to the voltage across the sampling capacitors)
Drive Circuit Requirements
The input sampling circuit of the ADS5547 has a high 3-dB analog bandwidth of 800 MHz making it possible to
sample input signals up to very high frequencies. To get best performance, it is recommended to have an
external R-C-R filter across the input pins (Figure 38). This helps to filter the glitches due to the switching of the
sampling capacitors. The R-C-R filter has to be designed to provide adequate filtering (for good performance)
and at the same time ensure sufficient bandwidth over the desired frequency range.
In addition, it is recommended to have a 15-Ω series resistor on each input line to damp out ringing caused by
the package parasitics. At higher input frequencies (> 100 MHz), a lower series resistance around 5 Ω to 10 Ω
should be used. It is also necessary to present low impedance (< 50 Ω) for the common-mode switching
currents. For example, this could be achieved by using two resistors from each input terminated to the
common-mode voltage (Vcm).
Using 10-Ω series resistance and 25 Ω-3.3 pF-25 Ω as the R-C-R filter, high effective bandwidth (700 MHz) can
be achieved, as shown in Figure 39.
Submit Documentation Feedback
29
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
APPLICATION INFORMATION (continued)
In addition to the above ADC requirements, the drive circuit may have to be designed to provide a low insertion
loss over the desired frequency range and matched impedance to the source. For this, the ADC input
impedance has to be taken into account (Figure 40).
Example Drive Circuits
A suitable configuration using RF transformers and including the R-C-R filter is shown in Figure 38. Note the
15-Ω series resistors and the low common-mode impedance (using 33-Ω resistors terminated to VCM).
ADS5547
Zi and TFADC
0.1 mF
WBC1-1TLB
15 W
(Note A)
WBC1-1TLB
INP
100 W
25 W
33 W
0.1 mF
3.3 pF
33 W
25 W
100 W
INM
1:1
15 W
(Note A)
1:1
VCM
A.
Use lower series resistance (≈ 5 Ω to 10 Ω) at high input frequencies (> 100 MHz)
Figure 38. Example Drive Circuit With RF Transformers
2
Magnitude − dB
1
0
-1
-2
-3
-4
-5
-6
0
100
200
300
400
500
600
700
800
900
1000
f − Frequency − MHz
Figure 39. Analog Input Bandwidth, TFADC (Actual Silicon Data)
30
Submit Documentation Feedback
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
APPLICATION INFORMATION (continued)
500
450
Magnitude − dB
400
350
300
250
200
150
100
50
0
0
100
200
300
400
500
600
700
800
900
1000
f − Frequency − MHz
Figure 40. Input Impedance, ZI
Using RF transformers
For optimum performance, the analog inputs have to be driven differentially. This improves the common-mode
noise immunity and even order harmonic rejection. The single-ended signal is fed to the primary winding of the
RF transformer. The transformer is terminated on the secondary side. Putting the termination on the secondary
side helps to shield the kickbacks caused by the sampling circuit from the RF transformer’s leakage
inductances. The termination is accomplished by two resistors connected in series, with the center point
connected to the 1.5 V common-mode (VCM pin 13).
At higher input frequencies, the mismatch in the transformer parasitic capacitance (between the windings)
results in degraded even-order harmonic performance. Connecting two identical RF transformers back to back
helps minimize this mismatch and good performance is obtained for high frequency input signals. An additional
termination resistor pair (Figure 38) may be required between the two transformers to improve the balance
between the P and M sides. The center point of this termination must be connected to ground. (Note that the
drive circuit has to be tuned to account for this additional termination, to get the desired S11 and impedance
match).
Submit Documentation Feedback
31
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
APPLICATION INFORMATION (continued)
Input Common-Mode
To ensure a low-noise common-mode reference, the VCM pin is filtered with a 0.1-µF low-inductance capacitor
connected to ground. The VCM pin is designed to directly drive the ADC inputs. The input stage of the ADC
sinks a common-mode current in the order of 342 µA (at 210 MSPS). Equation 1 describes the dependency of
the common-mode current and the sampling frequency.
(342 mA) x Fs
210 MSPS
(1)
This equation helps to design the output capability and impedance of the CM driving circuit accordingly.
Reference
ADS5547 has built-in internal references REFP and REFM, requiring no external components. Design schemes
are used to linearize the converter load seen by the references; this and the integration of the requisite
reference capacitors on-chip eliminates the need for external decoupling. The full-scale input range of the
converter can be controlled in the external reference mode as explained below. The internal or external
reference modes can be selected by controlling the MODE pin 23 (see Table 7 for details) or by programming
the serial interface register bit <REF>.
INTREF
Internal
Reference
VCM
INTREF
EXTREF
REFM
REFP
ADS5547
Figure 41. Reference Section
Internal Reference
When the device is in internal reference mode, the REFP and REFM voltages are generated internally.
Common-mode voltage (1.5 V nominal) is output on VCM pin, which can be used to externally bias the analog
input pins.
External Reference
When the device is in external reference mode, the VCM acts as a reference input pin. The voltage forced on
the VCM pin is buffered and gained by 1.33 internally, generating the REFP and REFM voltages. The differential
input voltage corresponding to full-scale is given by Equation 2.
32
Submit Documentation Feedback
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
APPLICATION INFORMATION (continued)
Full−scale differential input pp + (Voltage forced on VCM)
1.33
(2)
In this mode, the 1.5 V common-mode voltage to bias the input pins has to be generated externally. There is no
change in performance compared to internal reference mode.
Low Sampling Frequency Operation
For best performance at high sampling frequencies, ADS5547 uses a clock generator circuit to derive internal
timing for the ADC. The clock generator operates from 210 MSPS down to 50 MSPS in the DEFAULT SPEED
mode. The ADC enters this mode after applying reset (with serial interface configuration) or by tying SCLK pin to
low (with parallel configuration).
For low sampling frequencies (below 50 MSPS), the ADC must be put in the LOW SPEED mode. This mode
can be entered by:
• setting the register bit <LOW SPEED> through the serial interface, OR
• tying the SCLK pin to high (see Table 3) using the parallel configuration.
Clock Input
ADS5547 clock inputs can be driven differentially (SINE, LVPECL or LVDS) or single-ended (LVCMOS), with
little or no difference in performance between configurations. The common-mode voltage of the clock inputs is
set to VCM using internal 5-kΩ resistors as shown in Figure 42. This allows the use of transformer-coupled drive
circuits for sine wave clock, or ac-coupling for LVPECL, LVDS clock sources (Figure 43 and Figure 44)
VCM
VCM
5 kW
5 kW
CLKP
CLKM
ADS5547
Figure 42. Internal Clock Buffer
For best performance, it is recommended to drive the clock inputs differentially, reducing susceptibility to
common-mode noise. In this case, it is best to connect both clock inputs to the differential input clock signal with
0.1-µF capacitors, as shown in Figure 43.
Submit Documentation Feedback
33
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
APPLICATION INFORMATION (continued)
0.1 mF
CLKP
Differential Sine-Wave
or PECL or LVDS
Clock Input
0.1 mF
CLKM
ADS5547
Figure 43. Differential Clock Driving Circuit
A single-ended CMOS clock can be ac-coupled to the CLKP input, with CLKM (pin 11) connected to ground with
a 0.1-µF capacitor, as shown in Figure 44.
0.1 mF
CMOS Clock Input
CLKP
0.1 mF
CLKM
ADS5547
Figure 44. Single-Ended Clock Driving Circuit
For best performance, the clock inputs have to be driven differentially, reducing susceptibility to common-mode
noise. For high input frequency sampling, the use a clock source with very low jitter is recommended. Bandpass
filtering of the clock source can help reduce the effect of jitter. There is no change in performance with a
non-50% duty cycle clock input. Figure 31 shows the performance variation of the ADC versus clock duty cycle
Clock Buffer Gain
When using a sinusoidal clock input, the noise contributed by clock jitter improves as the clock amplitude is
increased. Therefore, using a large amplitude clock is recommended. In addition, the clock buffer has a
programmable gain option to amplify the input clock. The clock buffer gain can be set by programming the
register bits <CLK GAIN>. The clock buffer gain decreases monotonically from Gain 4 to Gain 0 settings.
34
Submit Documentation Feedback
ADS5547
www.ti.com
SLWS192 – NOVEMBER 2006
APPLICATION INFORMATION (continued)
Table 9. Clock Buffer Gain Programming
REGISTER ADDRESS
A7
A6
A5
A4
A3
A2
REGISTER DATA
A1
A0
D7
D6
D5
D4
D3
DESCRIPTION
D2
D1
D0
<CLK GAIN> – Clock buffer gain programmability, Gain decreases monotonically from Gain 4 to Gain 0
0
1
1
0
1
0
1
1
0
0
1
1
0
0
1
0
Gain 4
0
1
1
0
1
0
1
1
0
0
1
0
1
0
1
0
Gain 3
0
1
1
0
1
0
1
1
0
0
1
0
0
1
1
0
Gain 2
0
1
1
0
1
0
1
1
0
0
1
0
0
0
0
0
Gain 1 Default gain
0
1
1
0
1
0
1
1
0
0
1
0
0
0
1
1
Gain 0 Minimum gain
Programmable Gain
ADS5547 has programmable gain from 0 dB to 6 dB in steps of 1 dB. The corresponding full-scale input range
varies from 2 VPP down to 1 VPP, with 0 dB being the default gain. At high IF, this is especially useful as the
SFDR improvement is significant with marginal degradation in SNR.
The gain can be programmed using the serial interface (bits D3-D0 in register 0x68).
Table 10. Programmable Gain
REGISTER ADDRESS
A7
A6
A5
A4
A3
A2
REGISTER DATA
A1
A0
D7
D6
D5
D4
D3
DESCRIPTION
D2
D1
D0
<GAIN> Gain programming - Channel gain can be programmed from 0 to 6 dB for SFDR/SNR trade-off. For each gain setting, the
input full-scale range has to be proportionally scaled. For 6 dB gain, the full-scale range is 1 VPP compared to 2 VPP at 0 dB gain.
0
1
1
0
1
0
0
0
0
0
0
0
1
0
0
0
0 dB Default after reset
0
1
1
0
1
0
0
0
0
0
0
0
1
0
0
1
1 dB
0
1
1
0
1
0
0
0
0
0
0
0
1
0
1
0
2 dB
0
1
1
0
1
0
0
0
0
0
0
0
1
0
1
1
3 dB
0
1
1
0
1
0
0
0
0
0
0
0
1
1
0
0
4 dB
0
1
1
0
1
0
0
0
0
0
0
0
1
1
0
1
5 dB
0
1
1
0
1
0
0
0
0
0
0
0
1
1
1
0
6 dB
Power Down
ADS5547 has three power-down modes – global STANDBY, output buffer disabled, and input clock stopped.
Global STANDBY
This mode can be initiated by controlling SDATA (pin 28) or by setting the register bit <STBY> through the serial
interface. In this mode, the A/D converter, reference block and the output buffers are powered down and the
total power dissipation reduces to about 100 mW. The output buffers are in high impedance state. The wa