Specifications

EVAL-ADM1186
Rev. 0 | Page 9 of 24
EVALUATION BOARD OPERATION
Setting Voltage-Detection Levels
POWER REQUIREMENT
The input pins, VIN1 to VIN4, monitor one of four supply
voltages. The VIN1 pin monitors the 3.3 V rail. An external
resistor divider scales this voltage down for monitoring at the
VIN1 pin. The resistor ratio has been chosen so that the VIN1
voltage is 0.6 V when the 3.3 V rail is 5% below its nominal
value. For example, if R1 is 100 kΩ and R2 is 23.7 kΩ, a voltage
level of 3.13 V corresponds to 0.6 V at the VIN1 pin, as shown
in Figure 3.
The evaluation board requires a supply rail of 5 V, which can
be provided in one of two ways: either a dc supply of 5 V can
be directly connected to the terminal block, J1 with polarity as
marked on the PCB, or a 9 V dc supply can be connected to
the J3 barrel jack connector, which is then regulated down.
The center of the barrel jack connector is ground.
A switch, S1, selects which of the two supply options (jack
or term) is used by the board. At no time should a supply
connection be made to both J1 and J3.
VIN1
27.2kΩ
100kΩ
0.6V
TO LOGIC
CORE
ADM1186
3.3V
3.13V
0V
V
t
3.13V SUPPLY
GIVES 0.6V
AT VIN1 PIN
07620-003
When multiple EVAL-ADM1186-1EBZ boards are cascaded
together, power needs to be applied to a single board. Switch S1
must be set to the same position on all boards, depending on
whether the terminal block or barrel jack is in use. This should
be done before power is connected.
GETTING STARTED
This section demonstrates the basic operation of a main evalua-
tion board, performing a simple up and down sequence. The
detailed operation and configuration of the board is covered
in the following sections.
Figure 3. Setting the Undervoltage Threshold with an
External Resistor Divider
Board Supplies
The board supply of 5 V is used to generate the four rails moni-
tored by VIN1 to VIN2. The four other rails are nominally 3.3 V,
2.5 V, 1.8 V, and 1.5 V, but can be varied by about ±10% using
the variable resistors VR1 to VR4, respectively. This range is
sufficient to allow the user to set a supply above or below the
UV level to simulate undervoltage faults during a sequence or
once powered on.
To configure a single board to perform an up and down
sequence, use the following steps:
1. Set S2 to the down position. Set the S3 to S7 switches to the
Seq position. S3 is present only on EVAL-ADM1186-1EBZ.
Set switch banks S8 to S12 such that only Switch Position 2
on each bank of switches is on. S8 is present only on EVAL-
ADM1186-1EBZ.
Capacitor Timing and Single Stepping
2. On EVAL-ADM1186-1EBZ, ensure that jumpers are fitted
on J8 to J10.
The ADM1186-1 provides five timing pins, four used for
sequence delays and one for a blanking time. The ADM1186-2
provides four timing pins, three used for sequence delays and
one for a blanking time. A capacitor on each pin sets the time
delay for a given state during an up or a down sequence.
3. Ensure that jumpers are fitted in positions J4-A, J5-B, and
J6-B. Only J4 is present on EVAL-ADM1186-2EBZ.
4. Turn VR1 to VR4 so that they are fully clockwise.
5. Connect an appropriate supply to either J1 or J3 and set
Switch S1 accordingly.
The evaluation boards provide three fixed value capacitors for
each sequence delay that can be individually switched in or out,
as required, using S8 to S11 (S8 is found only on EVAL-ADM1186-
1EBZ). The capacitor values fitted are 10 nF, 100 nF, and 1 μF,
giving approximate delay times of 1 ms, 10 ms, and 100 ms.
The D1 and D2 LEDs should be on. Change Switch S2 to the
up position to start an up sequence. The four supplies turn
on, shown by LEDs D3 to D6. The PWRGD (power good)
and SEQ_DONE (sequence done) LEDs, D7 and D8, are also
turned on at the end of the up sequence. Setting S2 to down
reverses the sequence, turning off the LEDs.
The evaluation boards provide three fixed value capacitors
for the blanking delay that can be individually switched in or
out, as required, using S12. The capacitor values fitted are 10 nF,
47 nF, and 100 nF, giving approximate delay times of 1 ms, 5 ms,
and 10 ms.