Preliminary Technical Data
EVAL-AD5370/2/3EB
Rev. PrC | Page 3 of 12
GENERAL DESCRIPTION
FUNCTIONALITY OVERVIEW
The evaluation board for the AD537x is designed to allow the
user to fully evaluate all the functions and performance of the
AD537x prior to designing it into a system. The evaluation
board can be used in a stand-alone mode with the control
signals being provided through the 20 pin header J3 or it can be
connected to a PC using the USB cable supplied with the
evaluation board kit. Software is provided which allows the user
to program the various registers of the AD537x with ease. The
software operation is described later in this document.
POWER SUPPLIES
The evaluation board requires a +5V supply for DV
CC
. The V
DD
and V
SS
supplies can be any value within the power supply
limits as specified in the AD537x data sheet. Power supply
connections are made to the screw terminals of J2. The USB
interface, if used, gets its power supply from the USB port of the
PC. This power supply is not used by the AD537x or any of its
associated circuitry. When connecting the power supply leads it
is recommended that the supplies are turned off and that the
ground leads are connected first.
REFERENCE SELECTION
The evaluation board includes two voltage references ICs, the
ADR435 and ADR423 which are 5V and 3V references
respectively. An SMB connector is provided to allow an external
voltage to be connected for use as a reference. Link LK4 is used
to select which reference source is used by the AD537x as
shown in Table 1.
Table 1. Reference Selection using LK4
LK4
Position
Description
A The reference voltage is 3V (default)
B The reference voltage is 5V
C
The voltage on the SMB, EXT_REF is used as the
reference voltage
By default the voltage reference pins of the AD537x, VREF0 and
VREF1, both use the same reference, i.e. that selected by LK4. If
it is required that the reference pins should use different voltage
references this can be achieved by removing the 0Ω resistor
associated with each VREF pin. The required reference can then
be connected to the testpoint associated with the VREF pin.
Table shows the 0Ω resistor and testpoint associated with each
VREF pin.
Table 2. 0Ω Resistor and Testpoints for VREF pins
VREF Resistor Testpoint
VREF0 R17 T63
VREF1 R18 T64
USING THE USB INTERFACE
The software provided with the evaluation board kit allows the
user to program the registers of the AD537x via the USB
interface. It is important that the software supplied is installed
on the PC before the board is connected. See the Using the USB
Software section for more information. The USB circuitry gets
its power from the USB port of the PC and will generate the
required interface signals,
RESET, CLR, SYNC, SCLK etc. to
control the AD537x. To use the interface LK1, LK3 and LK8
should be in place. The function of these links is described in
Table 4.
STAND-ALONE OPERATION
The evaluation board can be used as a stand-alone device if
required. This has the advantage that it lets the user to connect
the interface pins of the AD537x to their own DSP or micro-
controller thus allowing them to write code to operate the
AD537x as their application requires. To use the board in stand-
alone mode the connection to the USB interface must be
removed. This is achieved by removing LK1, which will three-
state the connections to
CLR, LDAC, SYNC, SCLK and DIN. LK3
should be removed to isolate the
RESET
pin from the USB
interface and the push-button. The interface signals required to
control the AD537x can then be provided through the 20 pin
header J3. The pinout of J3 is shown in Table 3
Table 3. J3 Header Pinout
Pin Signal Pin Signal
1 DIN 8
LDAC
2 NC 10
CLR
3 SCLK 12
BUSY
4 NC 14
RESET
5 NC 16 NC
6
SYNC
18 NC
7,9,11,13,
15,17,19,20
DGND
