MAX197EVKIT-DIP Maxim Integrated, MAX197EVKIT-DIP Datasheet - Page 8

• Manufacturer Part Number: MAX197EVKIT-DIP
• Description: Data Conversion IC Development Tools Programmers, Development Systems
• Manufacturer: Maxim Integrated
• Series: MAX197r

Specifications of MAX197EVKIT-DIP

• Interface Type: Parallel
• Factory Pack Quantity: 1

Select an op amp based on its settling time. A fast set-
tling time is more important than a fast slew rate. Sites
U3 and U4 on the EV kit are industry-standard quad
op-amp pinouts in the voltage-follower configuration.
When using a slow op amp, extend the acquisition time
by using the “A” command in the control panel. The
68HC16 software allows acquisition times between
68µs and 6000µs. The 80C32 software allows acquisi-
tion times between 12µs and 560µs. A value of 0 dis-
ables the delay.
For high sampling rates, a fast settling op amp such as
Maxim’s MXL1014 performs quite well. Refer to the
Typical Timing Characteristics to see the relationship
between the value selected and the corresponding
external acquisition delay. For lower sampling rates,
any quad 741 type op amp should be adequate. The
LM348 is an inexpensive solution. For +5V single-sup-
ply systems, the MAX414 is recommended.
The MAX197 can use either its internal reference or an
external reference. On the EV kit, the internal reference
has been disabled by pulling the REFADJ pin up to
+5V (JU1) and driving the REF pin with a MAX874
4.096V reference (JU2).
When driving the REF pin with an external reference,
install a shunt at JU1 and place JU2 in the 1-2 position.
When driving the REFADJ pin with an external reference,
leave jumper JU1 open and place JU2 in the 2-3 position.
For lowest component count, the MAX197’s internal ref-
erence can be enabled by removing the shunts from JU1
and JU2. This enables the internal bandgap reference
and the reference buffer, driving REF internally to
4.096V. For best results, install a 0.01µF ceramic bypass
capacitor near the REFADJ pin (C7 on the EV kit).
MAX197 Evaluation Kit
8
_Detailed Description of Hardware
_______________________________________________________________________________________
Changing the Reference Voltage
Driving the Analog Inputs
The MAX197 EV kit software assumes a 4.096V refer-
ence voltage, unless otherwise specified. When using
other reference values, the reference value must be
specified when starting the program. For example, if
the REFADJ pin is driven by a 2.048V reference, start
the MAX197 software by typing:
Or, if the REFADJ pin is pulled high and REF is driven
by a 3.00V reference, start the MAX197 software by
typing:
Cut JU4 open. From the control panel, press F8 to
select external clock mode. Apply the external clock to
the EXTCLK input pad.
To evaluate the MAX199 using the MAX197 EV kit,
replace U1 with a MAX199. Then, at the DOS prompt,
start the MAX197 software by typing:
If the voltage reference is different than the default
4.096V, the MAX197 EV kit software should be
informed. For example, if the REFADJ pin is driven by a
2.048V reference, start the MAX197 software by typing:
Or, if the REFADJ pin is pulled high and REF is driven
by a 3.00V reference, start the MAX197 software by
typing:
Refer to the Changing the Reference Voltage section
for an explanation of how REF and REFADJ interact.
MAX197 REFADJ 2.048
MAX197 REF 3.00
MAX197 199
MAX197 199 REFADJ 2.048
MAX197 199 REF 3.00
Using an External Clock
Evaluating the MAX199