ADC14L040_14 Datasheet, PDF (26/33 Pages) Texas Instruments – 14-Bit, 40 MSPS, 235 mW A/D Converter

ADC14L040
SNAS311A – JUNE 2005 – REVISED APRIL 2006
+3.3V
+
10 PF
2 x 0.1 PF
CHOKE
0.1 PF
10 PF
1.8 to V_D Volts
0.1 PF
10 PF
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V_IN
1
**
0.1 PF
3
4 T1
2
0.1 PF
6
1
T1-6T
33
100 pF
33 100 pF
** may be replaced by Ckt in Fig. 5
Clock In
1k
1 _VREF
27
(MSB) D13
32 _{V RM}
26
D12
25
330
0.1 PF
0.1 PF
31
10 PF ₃₀
0.1 PF
V_RP
V _RN
ADC14L040
D11
D10 ²⁴
D9 ²³
D8 ²²
19
D7
18
D6
D5 ¹⁷
2 _VIN+
3 _VIN-
16
D4
15
D3
14
D2
8
PD
2 ^PD
D1 ¹³
(LSB) D0 ¹²
DF/DCS
2
DF/DCS
CLK
See
Text
49
49
74LVTH162374
CLK
Figure 5. Application Circuit using Transformer Drive Circuit
Output
Word
*
SIGNAL
INPUT
51
*
2.4k
5k, 1%
*
+
U1A
-
R1, 1%
5k, 1%
5k, 1%
5k, 1%
R2, 1%
+
U2B
-
R5, 1%
2V
to
33
V _IN+
100 pF
2.4k
5k, 1%
*
The ground
*
connections
indicated with an "*" should
be connected to a common
point in the analog ground
plane.
*
+
U2A
-
R3, 1%
5k, 1%
R4, 1%
+
U1B
-
5k, 1%
R6, 1%
Amplifiers:
two LMH6622s or
LMH6655s
100 pF
to
33
V_IN-
Figure 6. Differential Drive Circuit of Figure 5
POWER SUPPLY CONSIDERATIONS
The power supply pins should be bypassed with a 10 µF capacitor and with a 0.1 µF ceramic chip capacitor
close to each power pin. Leadless chip capacitors are preferred because they have low series inductance.
As is the case with all high-speed converters, the ADC14L040 is sensitive to power supply noise. Accordingly,
the noise on the analog supply pin should be kept below 100 mV_P-P.
No pin should ever have a voltage on it that is in excess of the supply voltages, not even on a transient basis. Be
especially careful of this during power turn on and turn off.
26
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