GE Industrial Solutions Austin Lynx SMT - Manual (Page 12)

Data Sheet
September 10, 2013 Austin Lynx TM SMT Non-isolated Power Modules:
3.0 – 5.5Vdc Input; 0.75Vdc to 3.63Vdc Output; 10A output current
LINEAGE POWER 12
Feature Description
Remote On/Off
The Austin Lynx TM SMT power modules feature an
On/Off pin for remote On/Off operation. The On/Off pin
is an open collector/drain logic input signal (Von/Off)
that is referenced to ground. Circuit configuration for
using the On/Off pin is shown in Figure 29. During a
logic-high (On/Off pin is pulled high internal to the
module) when the transistor Q1 is in the Off state, the
power module is ON. Maximum allowable leakage
current of the transistor when Von/off = V
IN,max
is 10µA.
Applying a logic-low when the transistor Q1 is turned-
On, the power module is OFF. During this state
VOn/Off must be less than 0.3V. When not using
positive logic On/off pin, leave the pin unconnected or
tie to V
IN.
Q1
R2
R1
Q2
R3
R4
Q3 CSS
GND
VIN+
ON/OFF
PWM Enable
+
_
ON/OFF
V
I
ON/OFF
MODULE
Figure 29. Circuit configuration for using positive
logic On/OFF.
Remote Sense
The Austin Lynx TM SMT power modules offer an option
for Remote Sense feature. When the device code
description includes a suffix “3”, sense pin is added to
the module and the Remote Sense feature is active.
See ordering information at the end of this document for
code description.
Remote sense minimizes the effects of distribution
losses by regulating the voltage at the load via Sense
and GND pins (see Figure 30). The voltage between
the Sense pin and Vo pin must not exceed 0.5V. The
amount of power delivered by the module is defined as
the output voltage multiplied by the output current (Vo x
Io). When using Remote Sense, the output voltage of
the module can increase, which if the same output is
maintained, increases the power output by the module.
Make sure that the maximum output power of the
module remains at or below the maximum rated power.
When the Remote Sense feature is not being used, tie
the Sense pin to output pin.
V O
C O M
V IN (+ )
C O M
R LO A D
R c ontact R distribution
R
c ontact
R
distribution
R
contac t
R contac t R distribution
R
distribution
S ense
Figure 32. Remote sense circuit configuration.
Overcurrent Protection
To provide protection in a fault (output overload)
condition, the unit is equipped with internal
current-limiting circuitry and can endure current limiting
continuously. At the point of current-limit inception, the
unit enters hiccup mode. The unit operates normally
once the output current is brought back into its specified
range. The typical average output current during hiccup
is 3A.
Input Undervoltage Lockout
At input voltages below the input undervoltage lockout
limit, module operation is disabled. The module will
begin to operate at an input voltage above the
undervoltage lockout turn-on threshold.
Overtemperature Protection
To provide protection in a fault condition, the unit is
equipped with a thermal shutdown circuit. The unit will
shutdown if the thermal reference point T
ref
, exceeds
125 o C (typical), but the thermal shutdown is not
intended as a guarantee that the unit will survive
temperatures beyond its rating. The module will
automatically restarts after it cools down.
Output Voltage Programming
The output voltage of the Austin Lynx TM SMT can be
programmed to any voltage from 0.75 Vdc to 3.63 Vdc
by connecting a single resistor (shown as Rtrim in
Figure 31) between the TRIM and GND pins of the
module. Without an external resistor between the TRIM
pin and the ground, the output voltage of the module is
0.7525 Vdc. To calculate the value of the resistor Rtrim
for a particular output voltage Vo, use the following
equation:
Ω




−
−
= 5110
7525 . 0
21070
Vo
Rtrim
For example, to program the output voltage of the
Austin Lynx
TM II module to 1.8 Vdc, Rtrim is calculated is
follows:
Ω −
−
= 



5110
7525 . 0 8 . 1
21070
Rtrim
Ω = k Rtrim 004 . 15