ISL70001ASEHEV1Z
AN1842 Rev.1.00
Page 4 of 9
Jun 11, 2013
TABLE 2. CONFIGURATION OPTIONS
REF. DESIGNATOR
SETTING
FUNCTION
J1
Short
Selects AVDD to be monitored by the EN pin through a resistive divider (R4 and R6) if S2 is toggled to the down
position.
Open
Allows an external voltage connected to TP5 to be monitored by the EN pin through a resistive divider (R4 and R6)
if S2 is toggled to the down position.
J2
Short 2-3
Selects Master mode, which forces the chip to run from the internal 1MHz oscillator. In Master mode, the SYNC
pin is an output that provides a nominal 1MHz clock signal.
Short 1-2
Selects Slave mode, which allows the chip to be synchronized to another ISL70001ASEH or to an external clock. In Slave
mode, the SYNC pin is an input that accepts a 1MHz synchronizing signal from the SYNC pin of another ISL70001ASEH
configured as a Master or from an external clock.
J3
Short
Loads the SYNC pin with R5, which is a 10k
Ω
resistor. If synchronization to an external clock over long distances
is required, it may be necessary to use a controlled impedance trace to avoid excessive ringing on the SYNC line.
If this is the case, the SYNC trace should be terminated into 50
Ω
at the Slave units. This can be accomplished by
replacing R5 on the Slave units with a 50
Ω
resistor. Please note that the SYNC pin of an ISL70001ASEH is not
designed to drive a 50
Ω
load.
Open
Disconnects the SYNC pin from R5.
J4
Short 2-3 Selects the 5V input UVLO threshold. Use this setting when the nominal input voltage is 5V.
Short 1-2
Selects the 3.3V input UVLO threshold. Use this setting when the nominal input voltage is 3.3V. Also use this
setting for nominal input voltages between 5V and 3.3V.
J5
Short
Selects the 0.8V preset output voltage option as long as J7 and J9-J13 are open.
Open
Allows output voltages other than 0.8V to be selected.
J7
Short
Selects the 1.0V preset output voltage option as long as J5 and J9-J13 are open.
Open
Allows output voltages other than 1.0V to be selected.
J9
Short
Selects the 1.2V preset output voltage option as long as J5, J7 and J10-J13 are open.
Open
Allows output voltages other than 1.2V to be selected.
J10
Short
Selects the 1.8V preset output voltage option as long as J5, J7, J9 and J11-J13 are open.
Open
Allows output voltages other than 1.8V to be selected.
J11
Short
Selects the 2.5V preset output voltage option as long as J5, J7, J9-J10 and J12-J13 are open.
Open
Allows output voltages other than 2.5V to be selected.
J12
Short
Selects the 3.3V preset output voltage option as long as J5, J7, J9-J11 and J13 are open.
Open
Allows output voltages other than 3.3V to be selected.
J13
Short
Selects the adjustable output voltage option as long as J5, J7 and J9-J12 are open. Potentiometer, R17, can be
used to adjust the output voltage.
Open
Allows the preset output voltage options to be selected.
J15
Short
Shorts out R18, allowing normal operation of the evaluation board.
Open
Facilitates control loop stability measurements by allowing a signal to be injected across R18.
S2
Short 2-3 S1 in the up position shorts contacts 2-3. This pulls the EN pin low to disable the output voltage.
Short 1-2
S1 in the down position shorts contacts 1-2. This enables the output voltage as long as the voltage on the EN pin
exceeds 0.6V.