Data Sheet
12V Austin LynxTM SMT Non-isolated Power Modules Programmable:
10 – 14Vdc input; 0.75Vdc to 5.5Vdc Output; 10A output current
April 8, 2008
the thermal shutdown is not intended as a guarantee that
the unit will survive temperatures beyond its rating. The
module will automatically restart after it cools down.
Feature Description
Remote On/Off
The 12V Austin Lynx Programmable SMT power modules
feature an On/Off pin for remote On/Off operation. 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 the module on and off using remote
On/Off, connect an open collector npn transistor between
the On/Off pin and the ground pin (See Figure 27).
Output Voltage Programming
The output voltage of the 12V Austin Lynx Programmable
SMT module can be programmed to any voltage from
0.75Vdc to 5.5Vdc by connecting a resistor (shown as
Rtrim in Figure 28) between Trim and GND pins of the
module. Without an external resistor between Trim and
GND pins, the output of the module will be 0.7525Vdc.
To calculate the value of the trim resistor, Rtrim for a
desired output voltage, use the following equation:
During a logic-high (On/Off pin is pulled high internal to
the module) when the transistor is in the Off state, the
power module is ON. The maximum allowable leakage
current of the transistor when Von/off = VIN,max is 10µA.
During a logic-low when the transistor is turned-on, the
power module is OFF. During this state VOn/Off is less
than 0.3V and the maximum IOn/Off = 1mA.
10500
⎡
⎤
Rtrim =
−1000 Ω
⎢
⎥
Vo − 0.7525
⎣
⎦
For example, to program the output voltage of the 12V
Austin Lynx Programmable SMT module to 1.8 Vdc, Rtrim
is calculated is follows:
VIN+
MODULE
R2
10500
⎡
⎤
ON/OFF
Q2
Rtrim =
−1000
⎢
⎣
⎥
⎦
+
R1
1.8 − 0.75
V
ON/OFF
I
Rtrim = 9.024kΩ
ON/OFF
PWM Enable
R3
R4
Vout
Q1
VIN(+)
VO(+)
Q3
CSS
ON/OFF
GND
_
LOAD
TRIM
Figure 27. Remote On/Off Implementation.
Overcurrent Protection
R
trim
GND
To provide protection in a fault (output overload)
condition, the unit is equipped with internal
Figure 28. Circuit configuration for programming
output voltage using an external resistor.
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 3 A.
Table 1 provides Rtrim values required for some common
output voltages
Input Undervoltage Lockout
Table 1
VO, set (V)
0.7525
1.2
Rtrim (KΩ)
Open
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.
22.46
1.5
13.05
Overtemperature Protection
1.8
9.024
To provide over temperature protection in a fault
2.5
5.009
condition, the unit relies upon the thermal protection
feature of the controller IC. The unit will shutdown if the
thermal reference point Tref, exceeds 125oC (typical), but
3.3
3.122
5.0
1.472
LINEAGE POWER
12
LINEAGEPOWER [ LINEAGE POWER CORPORATION ]
