Rainbow Electronics MAX104 - Manual (Page 25)

Thermal Performance
The MAX104 has been modeled to determine the ther-
mal resistance from junction to ambient. Table 7 lists
the ADC’s thermal performance parameters:
Ambient Temperature: T A = +70°C
Heatsink Dimensions: 25mm x 25mm x 10mm
PC Board Size and Layout: 4" x 4"
2 Signal Layers
2 Power Layers
Heatsink Manufacturers
Aavid Engineering and IERC provide open-tool, low-
profile heatsinks, fitting the 25mm x 25mm ESBGA
package.
Aavid Engineering, Inc.
Phone: 714-556-2665
Heatsink Catalog #: 335224B00032
Heatsink Dimensions: 25mm x 25mm x 10mm
International Electronic Research Corporation (IERC)
Phone: 818-842-7277
Heatsink Catalog #: BDN09-3CB/A01
Heatsink Dimensions: 23.1mm x 23.1mm x 9mm
Bypassing/Layout/Power Supply
Grounding and power-supply decoupling strongly influ-
ence the MAX104’s performance. At 1GHz clock fre-
quency and 8-bit resolution, unwanted digital crosstalk
may couple through the input, reference, power supply,
and ground connections and adversely influence the
dynamic performance of the ADC. Therefore, closely
follow the grounding and power-supply decoupling
guidelines (Figure 22).
Maxim strongly recommends using a multilayer printed
circuit board (PCB) with separate ground and power-
supply planes. Since the MAX104 has separate analog
and digital ground connections (GNDA, GNDI, GNDR,
and GNDD, respectively), the PCB should feature sep-
arate analog and digital ground sections connected at
only one point (star ground at the power supply). Digital
signals should run above the digital ground plane, and
analog signals should run above the analog ground
plane. Keep digital signals far away from the sensitive
analog inputs, reference inputs, and clock inputs. High-
speed signals, including clocks, analog inputs, and
digital outputs, should be routed on 50
Ω
microstrip
lines, such as those employed on the MAX104EVKIT.
The MAX104 has separate analog and digital power-
supply inputs: V
EE (-5V analog and substrate supply)
and V CC I (+5V) to power the T/H amplifier, clock distri-
bution, bandgap reference, and reference amplifier;
V
CC A (+5V) to supply the ADC’s comparator array;
V CC O (+3V to V CC D) to establish power for all PECL-
based circuit sections; and V CC D (+5V) to supply all
logic circuits of the data converter.
The MAX104 V EE supply contacts must not be left
open while the part is being powered up. To avoid this
condition, add a high-speed Schottky diode (such as a
Motorola 1N5817) between V
EE and GNDI. This diode
prevents the device substrate from forward biasing,
which could cause latchup.
MAX104
±5V, 1Gsps, 8-Bit ADC with
On-Chip 2.2GHz Track/Hold Amplifier
______________________________________________________________________________________ 25
Table 7. Thermal Performance for
MAX104 With or Without Heatsink
16.5 0 12.5
14.3 9.4 200
13 8.3 400
12.5 7.4 800
6
8
10
12
14
16
18
0 200 100 300 400 500 600 700 800
THERMAL RESISTANCE vs. AIRFLOW
AIRFLOW (linear ft./min.)
θ JA
(°C/W)
WITHOUT
HEATSINK
WITH HEATSINK
Figure 21. MAX104 Thermal Performance
MAX104
θ
JA (°C/W)
WITHOUT
HEATSINK
WITH HEATSINK
AIRFLOW
(linear ft./min.)