GE Industrial Solutions 12V Austin MicroLynx 5A - Manual (Page 12)

GE
Data Sheet
12V Austin MicroLynx TM 5A: Non-Isolated DC-DC Power Modules
10Vdc –14Vdc input; 0.75Vdc to 5.5Vdc output; 5A Output Current
May 6, 2013 ©2013 General Electric Company. All rights reserved. Page 12
Feature Description
Remote On/Off
The Austin MicroLynx TM SMT 12V power modules feature an
On/Off pin for remote On/Off operation of the module. If not
using the remote On/Off pin, leave the pin open (module will be
On). The On/Off pin signal (Von/Off) is referenced to ground. To
switch module on and off using remote On/Off, connect an
open collector pnp transistor between the On/Off pin and the
V
IN
pin (See Figure 27).
When the transistor Q1 is in the OFF state, the power module is
ON (Logic Low on the On/Off pin of the module) and the
maximum Von/off of the module is 0.4 V. The maximum
allowable leakage current of the transistor when Von/off = 0.4V
and V
IN
= V
IN,max
is 10μA. During a logic-high when the
transistor is in the active state, the power module is OFF.
During this state VOn/Off =10 - 14V and the maximum IOn/Off =
1mA.
V
IN
(+)
GND
Enable 20k
20k
On/Off
Pin
Css
I
On/Off
Lynx-series Module
Figure 27. Remote On/Off Implementation
Remote On/Off can also be implemented using open-collector
logic devices with an external pull-up resistor. Figure 28a
shows the circuit configuration using this approach. Pull-up
resistor, R
pull-up
, for the configuration should be 68k (+/-5%) for
proper operation of the module over the entire temperature
range.
Q1
R1
R2
Q2 CSS
GND
PWM Enable
ON/OFF
VIN+
ON/OFF
_
+
V
I
MODULE
pull-up
R
ON/OFF
Figure 27a. Remote On/Off Implementation using logic-level
devices and an external pull-up resistor
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 2A.
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 over temperature protection in a fault condition, the
unit relies upon the thermal protection feature of the controller
IC. The unit will shutdown if the thermal reference point T
ref2
,
(see Figure 31) exceeds 140 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.