General Description
The MAX1444 10-bit, 3V analog-to-digital converter
(ADC) features a pipelined 10-stage ADC architecture
with fully differential wideband track-and-hold (T/H)
input and digital error correction incorporating a fully
differential signal path. This ADC is optimized for lowpower, high dynamic performance applications in
imaging and digital communications. The MAX1444
operates from a single 2.7V to 3.6V supply, consuming
only 57mW while delivering a 59.5dB signal-to-noise
ratio (SNR) at a 20MHz input frequency. The fully differential input stage has a 400MHz -3dB bandwidth and
may be operated with single-ended inputs. In addition
to low operating power, the MAX1444 features a 5µA
power-down mode for idle periods.
An internal 2.048V precision bandgap reference is
used to set the ADC full-scale range. A flexible reference structure allows the user to supply a buffered,
direct, or externally derived reference for applications
requiring increased accuracy or a different input voltage range.
Higher speed, pin-compatible versions of the MAX1444
are also available. Please refer to the MAX1446 data
sheet (60Msps) and the MAX1448 data sheet
(80Msps).
The MAX1444 has parallel, offset binary, CMOS-compatible three-state outputs that can be operated from
1.7V to 3.6V to allow flexible interfacing. The device is
available in a 5x5mm 32-pin TQFP package and is
specified over the extended industrial (-40°C to +85°C)
temperature range.
________________________Applications
Ultrasound Imaging
CCD Imaging
Baseband and IF Digitization
Digital Set-Top Boxes
Video Digitizing Applications
Features
o Single 3.0V Operation
o Excellent Dynamic Performance
59.5dB SNR at f
IN
= 20MHz
74dBc SFDR at f
IN
= 20MHz
o Low Power
19mA (Normal Operation)
5μA (Shutdown Mode)
o Fully Differential Analog Input
o Wide 2V
p-p Differential Input Voltage Range
o 400MHz -3dB Input Bandwidth
o On-Chip 2.048V Precision Bandgap Reference
o CMOS-Compatible Three-State Outputs
o 32-Pin TQFP Package
o Evaluation Kit Available
MAX1444
10-Bit, 40Msps, 3.0V, Low-Power
ADC with Internal Reference
________________________________________________________________
Maxim Integrated Products
1
Pin Configuration
19-1745; Rev 3; 8/10
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
EVALUATION KIT
AVAILABLE
Ordering Information
Functional Diagram appears at end of data sheet.
/V Denotes an automotive qualified part.
+
Denotes a lead(Pb)-free/RoHS-compliant package.
PART TEMP RANGE PIN-PACKAGE
MAX1444EHJ -40°C to +85°C 32 TQFP
MAX1444EHJ/V+ -40°C to +85°C 32 TQFP
TOP VIEW
REFIN
GND
REFOUT
REFN
COM
V
GND
GND
IN+
REFP
32 28
1
2
3
DD
4
5
6
7
IN-
8GND
10
9
DD
DD
V
V
293031
MAX1444
CLK
GND
D0
D1
D2
D3
25
27
26
24 D4
OGND
23
T.P.
22
OV
21
DD
D5
20
D6
19
D7
18
17
D8
14
13
15
1611 12
D9
OE
PD
GND
TQFP
MAX1444
10-Bit, 40Msps, 3.0V, Low-Power
ADC with Internal Reference
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VDD= 3V; OVDD= 2.7V; 0.1µF and 1µF capacitors from REFP, REFN, and COM to GND; V
REFIN
= 2.048V; REFOUT connected to
REFIN through a 10kΩ resistor; V
IN
= 2V
P-P
(differential with respect to COM); CL= 10pF at digital outputs; f
CLK
= 40MHz; TA= T
MIN
to T
MAX
, unless otherwise noted. ≥ +25°C guaranteed by production test, < +25°C guaranteed by design and characterization; typi-
cal values are at T
A
= +25°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 in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
VDD, OVDDto GND ...............................................-0.3V to +3.6V
OGND to GND.......................................................-0.3V to +0.3V
IN+, IN- to GND........................................................-0.3V to V
DD
REFIN, REFOUT, REFP,
REFN, and COM to GND........................-0.3V to (V
DD
+ 0.3V)
OE, PD, CLK to GND..................................-0.3V to (V
DD
+ 0.3V)
D9–D0 to GND.........................................-0.3V to (OV
DD
+ 0.3V)
Continuous Power Dissipation (T
A
= +70°C)
32-Pin TQFP (derate 18.7mW/°C above +70°C).....1495.3mW
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-60°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) .......................................+260°C
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
DC ACCURACY
Resolution 10 Bits
Integral Nonlinearity INL fIN = 7.51MHz, TA ≥ +25°C ±0.6 ±1.9 LSB
Differential Nonlinearity DNL
Offset Error <±0.1 ±1.7 % FS
Gain Error TA ≥ +25°C 0 ±2% FS
ANALOG INPUT
Input Differential Range V
Common-Mode
Voltage Range
Input Resistance R
Input Capacitance C
CONVERSION RATE
Maximum Clock Frequency f
Data Latency 5.5 Cycles
DYNAMIC CHARACTERISTICS (f
Signal-to-Noise Ratio SNR
Signal-to-Noise + Distortion
(Up to 5th harmonic)
f
IN
guaranteed
DIFF
V
COM
CLK
= 40MHz, 4096-point FFT)
CLK
SINAD
Differential or single-ended inputs ±1.0 V
Switched capacitor load 50 kΩ
IN
IN
fIN = 7.51MHz 57.5 59.5
fIN = 19.91MHz 56.3 59.5
f
IN
fIN = 7.51MHz 57 59.4
fIN = 19.91MHz 56.1 59
f
IN
fIN = 7.51MHz 67 75
fIN = 19.91MHz 66 74Spurious-Free Dynamic Range SFDR
f
IN
= 7.51MHz, no missing codes
= 39.9MHz (Note 1) 58.5
= 39.9MHz (Note 1) 58.3
= 39.9 MHz (Note 1) 72.5
40 MHz
±0.4 ±1.0 LSB
VDD/2
±0.5
5pF
V
dB
dB
dBc
MAX1444
10-Bit, 40Msps, 3.0V, Low-Power
ADC with Internal Reference
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VDD= 3V; OVDD= 2.7V; 0.1µF and 1µF capacitors from REFP, REFN, and COM to GND; V
REFIN
= 2.048V; REFOUT connected to
REFIN through a 10kΩ resistor; V
IN
= 2V
P-P
(differential with respect to COM); CL= 10pF at digital outputs; f
CLK
= 40MHz; TA= T
MIN
to T
MAX
, unless otherwise noted. ≥ +25°C guaranteed by production test, < +25°C guaranteed by design and characterization; typi-
cal values are at T
A
= +25°C.)
fIN = 7.51MHz -75
fIN = 19.91MHz -74
Third-Harmonic Distortion HD3
f
IN
= 39.9MHz (Note 1) -72.5
dBc
Two-Tone Intermodulation
Distortion
IMD
f
1
= 11.5MHz at -6.5dBFS
f
2
= 13.5MHz at -6.5dBFS
(Note 2)
-76 dBc
Third-Order Intermodulation
Distortion
IM3
f
1
= 11.5MHz at -6.5dBFS
f
2
= 13.5MHz at -6.5dBFS
(Note 2)
-76 dBc
fIN = 7.51MHz -73.8 -65
fIN = 19.91MHz -72.2 -65
Total Harmonic Distortion
(First 4 Harmonics)
THD
f
IN
= 39.9MHz (Note 1) -70
dBc
Small-Signal Bandwidth Input at -20dBFS, differential inputs 500 MHz
Full-Power Bandwidth FPBW Input at -0.5dBFS, differential inputs 400 MHz
Aperture Delay t
AD
1ns
Aperture Jitter t
AJ
2
ps
RMS
Overdrive Recovery Time For 1.5 × full-scale input 2 ns
Differential Gain ±1%
Differential Phase
Output Noise IN+ = IN- = COM 0.2
INTERNAL REFERENCE
Reference Output Voltage
2.048 ±1% V
Reference Temperature
Coefficient
BUFFERED EXTERNAL REFERENCE (V
REFIN
= 2.048V)
REFIN Input Voltage
V
Positive Reference Output
Voltage
V
REFP
V
Negative Reference Output
Voltage
V
Common-Mode Level V
COM
V
Differential Reference Output
Voltage Range
ΔV
REF
= V
REFP
- V
REFN
, TA ≥ +25°C 0.98
REFOUT
TC
REF
V
REFIN
V
REFN
ΔV
REF
R
REFIN
±0.25
2.048
2.012
0.988
VDD / 2
1.024
MAX1444
10-Bit, 40Msps, 3.0V, Low-Power
ADC with Internal Reference
4 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(VDD= 3V; OVDD= 2.7V; 0.1µF and 1µF capacitors from REFP, REFN, and COM to GND; V
REFIN
= 2.048V; REFOUT connected to
REFIN through a 10kΩ resistor; V
IN
= 2V
P-P
(differential with respect to COM); CL= 10pF at digital outputs; f
CLK
= 40MHz; TA= T
MIN
to T
MAX
, unless otherwise noted. ≥ +25°C guaranteed by production test, < +25°C guaranteed by design and characterization; typi-
cal values are at T
A
= +25°C.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Maximum REFP, COM Source
Current
Maximum REFP, COM Sink
Current
Maximum REFN Source Current I
Maximum REFN Sink Current I
UNBUFFERED EXTERNAL REFERENCE (V
REFP, REFN Input Resistance
REFP, REFN, COM Input
Capacitance
Differential Reference Input
Voltage Range
COM Input Voltage Range V
I
S OU RC E
I
SINK
S OU RC E
SINK
= AGND, reference voltage applied to REFP, REFN, and COM)
REFIN
,
R
R
ΔV
REFP
REFN
C
REF
COM
Measured between REFP and COM
and REFN and COM
IN
ΔV
REF
= V
REFP
- V
REFN
-250 µA
1.024
±10%
VDD / 2
±10%
5mA
250 µA
-5 mA
4kΩ
15 pF
V
V
REFP Input Voltage V
REFN Input Voltage V
DIGITAL INPUTS (CLK, PD, OE)
Input High Threshold V
Input Low Threshold V
REFP
REFN
IH
IL
CLK
PD, OE
CLK
PD, OE
0.8 ×
V
DD
0.8 ×
OV
DD
V
C OM
ΔV
V
COM
ΔV
RE F
2
REF
2
+
/
-
/
0.2 ×
V
DD
0.2 ×
OV
DD
V
V
V
V
MAX1444
10-Bit, 40Msps, 3.0V, Low-Power
ADC with Internal Reference
_______________________________________________________________________________________ 5
ELECTRICAL CHARACTERISTICS (continued)
(VDD= 3V; OVDD= 2.7V; 0.1µF and 1µF capacitors from REFP, REFN, and COM to GND; V
REFIN
= 2.048V; REFOUT connected to
REFIN through a 10kΩ resistor; V
IN
= 2V
P-P
(differential with respect to COM); CL= 10pF at digital outputs; f
CLK
= 40MHz; TA= T
MIN
to T
MAX
, unless otherwise noted. ≥ +25°C guaranteed by production test, < +25°C guaranteed by design and characterization; typi-
cal values are at T
A
= +25°C.)
Note 1: SNR, SINAD, THD, SFDR, and HD3 are based on an analog input voltage of -0.5dBFS referenced to a 1.024V full-scale
input voltage range.
Note 2: Intermodulation distortion is the total power of the intermodulation products relative to the individual carrier. This number is
6dB better if referenced to the two-tone envelope.
Note 3: Digital outputs settle to V
IH
, VIL.
Note 4: REFIN is driven externally. REFP, COM, and REFN are left open while powered down.
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Input Hysteresis V
Input Leakage
Input Capacitance C
HYST
I
IH
I
IL
IN
VIH = VDD = OV
DD
VIL = 0V ±5
DIGITAL OUTPUTS (D9–D0)
Output Voltage Low V
Output Voltage High V
Three-State Leakage Current I
Three-State Output Capacitance C
LEAK
OUT
OL
OH
I
= 200μA 0.2 V
SINK
I
SOURCE
OE = OV
OE = OV
= 200μA
DD
DD
OV
POWER REQUIREMENTS
Analog Supply Voltage V
Output Supply Voltage OV
Analog Supply Current I
Output Supply Current I
Power-Supply Rejection PSRR
DD
DD
VDD
OVDD
O p er ati ng , f
S hutd ow n, cl ock i d l e, P D = O E = OV
O p er ati ng , f
S hutd ow n, cl ock i d l e, P D = O E = OV
= 19.91M H z at - 0.5d BFS 19 27 mA
I N
D D
= 19.91M H z at - 0.5d BFS 4.5 mA
I N
D D
Offset ±0.1 mV/V
Gain ±0.1 %/V
TIMING CHARACTERISTICS
CLK Rise to Output Data Valid t
OE Fall to Output Enable t
OE Rise to Output Disable t
ENABLE
DISABLE
CLK Pulse Width High t
CLK Pulse Width Low t
Wake-up Time t
DO
CH
CL
WAKE
Figure 6 (Note 3) 5 8 ns
Figure 5 10 ns
Figure 5 15 ns
Figure 6, clock period 25ns 12.5 ±3.8 ns
Figure 6, clock period 25ns 12.5 ±3.8 ns
(Note 4) 1.7 µs
0.1 V
5pF
-
DD
0.2
±10 µA
5pF
2.7 3.0 3.6 V
1.7 3.0 3.6 V
415µA
120µA
±5
µA
V
MAX1444-01
-100
-70
-80
-90
-50
-60
-10
-20
-30
-40
0
0 2 4 6 8101214161820
ANALOG INPUT FREQUENCY (MHz)
AMPLITUDE (dB)
SINAD = 59dB
SNR = 59.3dB
THD = -71.6dBc
SFDR = 73dBc
FFT PLOT (fIN = 7.51MHz,
8192-POINT FFT, DIFFERENTIAL INPUT)
3RD HARMONIC
2ND HARMONIC
MAX1444-02
-100
-70
-80
-90
-50
-60
-10
-20
-30
-40
0
0 2 4 6 8101214161820
ANALOG INPUT FREQUENCY (MHz)
AMPLITUDE (dB)
SINAD = 58.9dB
SNR = 59.1dB
THD = -72.8dBc
SFDR = 75.2dBc
FFT PLOT (fIN = 19.91MHz,
8192-POINT FFT, DIFFERENTIAL INPUT)
3RD HARMONIC
2ND HARMONIC
MAX1444-03
-100
-70
-80
-90
-50
-60
-10
-20
-30
-40
0
0 5 10 15 20 25
FFT PLOT (fIN = 47MHz,
8192-POINT FFT, DIFFERENTIAL INPUT)
ANALOG INPUT FREQUENCY (MHz)
AMPLITUDE (dB)
SINAD = 58.1dB
SNR = 58.4dB
THD = -69.7dBc
SFDR = 72.4dBc
3RD HARMONIC
2ND HARMONIC
MAX1444-04
-100
-70
-80
-90
-50
-60
-10
-20
-30
-40
0
0 2 4 6 8101214161820
ANALOG INPUT FREQUENCY (MHz)
AMPLITUDE (dB)
SINAD = 59.7dB
SNR = 60dB
THD = -71.8dBc
SFDR = 75dBc
FFT PLOT (fIN = 7.51MHz,
8192-POINT FFT, SINGLE-ENDED INPUT)
3RD HARMONIC
2ND HARMONIC
MAX1444-05
-100
-70
-80
-90
-50
-60
-10
-20
-30
-40
0
0 2 4 6 8101214161820
ANALOG INPUT FREQUENCY (MHz)
AMPLITUDE (dB)
SINAD = 59.1dB
SNR = 59.2dB
THD = -74.6dBc
SFDR = 77.6dBc
FFT PLOT (fIN = 19.91MHz,
8192-POINT FFT, SINGLE-ENDED INPUT)
3RD HARMONIC
2ND HARMONIC
6
1 100 1000
FULL-POWER INPUT BANDWIDTH
vs. ANALOG INPUT FREQUENCY (SINGLE ENDED)
-6
-8
-4
-2
0
2
4
MAX1444-06
ANALOG INPUT FREQUENCY (MHz)
GAIN (dB)
10
6
1 100 1000
SMALL-SIGNAL INPUT BANDWIDTH
vs. ANALOG INPUT FREQUENCY (SINGLE ENDED)
-6
-8
-4
-2
0
2
4
MAX1444-07
ANALOG INPUT FREQUENCY (MHz)
GAIN (dB)
10
VIN = 100mVp-p
MAX1444-08
-100
-70
-80
-90
-50
-60
-10
-20
-30
-40
0
0 5 10 15 20 25
ANALOG INPUT FREQUENCY (MHz)
AMPLITUDE (dB)
TWO-TONE INTERMODULATION
8192-POINT IMD (DIFFERENTIAL INPUT)
f1 = 11.5MHz AT
-6.5dB FS
f
2
= 13.5MHz AT
-6.5dB FS
IMD = -76dBc
80
40
110100
SPURIOUS-FREE DYNAMIC RANGE
vs. ANALOG INPUT FREQUENCY
50
45
MAX1444-09
ANALOG INPUT FREQUENCY (MHz)
SFDR (dBc)
60
55
65
70
75
SINGLE ENDED
DIFFERENTIAL
MAX1444
10-Bit, 40Msps, 3.0V, Low-Power
ADC with Internal Reference
6 _______________________________________________________________________________________
Typical Operating Characteristics
(VDD= 3.0V, OVDD= 2.7V, internal reference, differential input at -0.5dB FS, f
CLK
= 40MHz, CL≈ 10pF, TA= +25°C, unless other-
wise noted.)