2
dc2423af
DEMO MANUAL DC2423A
OPERATING PRINCIPLES
OVERVIEW
The LTM9100 contains an isolated DC/DC converter, deliv
-
ering power to V
S
at 10.4V and V
CC2
at 5V from the input
supply, V
CC
. Isolation is maintained by the separation of
GND and V
EE
so that significant operating voltages and
transients can exist without affecting the operation of the
LTM9100. The logic side ON pin enables or shuts down
the LTM9100. The isolated side GATE pin and MOSFET
turn on are controlled by the logic side EN input. The logic
side also has two status pins, PG for power good and
ALERT to indicate an internal fault. LEDs indicate if either
pin has been activated.
All logic side signals are referenced to the logic supply
pin V
L
, which may be connected to V
CC
or to the V
L
input
by jumper (JP2) selection.
The DC2423A is designed to be used either stand-alone
or interfaced directly with a DC590 isolated serial control
-
ler or a DC2026 Linduino
®
One. The QuickEval
™
software
may be used with either the DC590 or DC2026 (when
running the DC590 Arduino code). Example Arduino
code specifically for the DC2423A is also available for the
DC2026. The LTM9100 includes an I
2
C/SMBus interface
for communication to its isolated side control and status
functions, as well as ADC results. The isolated side includes
two jumpers for selection of the I
2
C address.
The isolated side of the LTM9100 controls the turn-on of
an external MOSFET. The MOSFET leads are connected by
screw terminal block, and its body is screw mounted to
a heatsink and PCB. This allows the MOSFET to be easily
interchanged or replaced. The design can accommodate
TO-247 (default), TO-264, and TO-220 packages.
The demo board can be connected for either high side or
low side applications. Banana jacks are provided and clearly
labeled for voltage input and load connection depending
on the selected configuration. The line monitor jumper
(JP7) must also be configured for the same configuration
so that the LTM9100 ADC reports the proper input voltage.
LEDs indicate the presence of line voltage in blue and load
voltage in yellow once the MOSFET has been turned on.
An optional capacitive load with banana connections has
been provided on the demo board. It may be used by
externally wiring to the proper load terminals.
Transient suppression is included to protect the MOSFET
and on board load capacitor for the –B version of the
demo board. The GATE pin and SENSE
+
pins include
external overvoltage/overcurrent protection in the event
the MOSFET shorts either drain to gate or drain to source,
protecting the LTM9100.
The DC2423A may be configured for other input voltages
and load currents by changing a handful of components.
The assembly table located on the demo board schematic
lists the component variations between the –A and –B
versions.
JUMPERS
DC2423A contains 7 jumpers, and a 14-pin connector
for the I
2
C interface. The jumpers provide either pin or
function configuration, a description of jumper follows.
JP1: EEPROM Program (PG) or Write Protect (WP). For
factory use only in programming the demo board ID for
QuickEval. Default position: Not Populated.
JP2: V
L
Supply Jumper. May be connected to V
CC
input
terminal or V
L
(default) input terminal.
JP3: ON Jumper. Enables the LTM9100 in the ON (default)
position, and disables operation in the OFF position. The
ON terminal either monitors the state of the ON jumper,
or if the ON jumper is removed, allows the ON terminal
to be externally driven.
JP4: EN Jumper. Enables the LTM9100 GATE pin, provided
both UV and OV functions are satisfied, in the ON (default)
position, and disables GATE in the OFF position. Operation
of the GATE pin may be subsequently controlled via the
I
2
C interface, but the EN pin must be in the high position.
See the LTM9100 data sheet for I
2
C only operation. The
EN terminal either monitors the state of the EN jumper,
or if the EN jumper is removed, allows the EN terminal to
be externally driven.
