GE Industrial Solutions 12V TLynx 20A - Manual (Page 15)

GE
Data Sheet
12V TLynx TM 20A: Non-Isolated DC-DC Power Modules
4.5Vdc –14Vdc input; 0.69Vdc to 5.5Vdc output; 20A Output Current
May 2, 2013 ©2013 General Electric Company. All rights reserved. Page 15
24.9K
Q1
ON/OFF
VIN+
GND _
+
PWM Enable
V
ON/OFF
MODULE
I
Rpullup1
ON/OFF
22K
Q2
23K
12.1K
Figure 43. Circuit configuration for using negative On/Off
logic.
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.
Over Temperature Protection
To provide protection in a fault condition, the unit is equipped
with a thermal shutdown circuit. The unit will shutdown if the
overtemperature threshold of 135 o C is exceeded at the thermal
reference point T
ref
. The thermal shutdown is not intended as a
guarantee that the unit will survive temperatures beyond its
rating. Once the unit goes into thermal shutdown it will then
wait to cool before attempting to restart.
Input Undervoltage Lockout
At input voltages below the input undervoltage lockout limit, the
module operation is disabled. The module will begin to operate
at an input voltage above the undervoltage lockout turn-on
threshold.
Output Voltage Programming
The output voltage of the 12V TLynx TM module can be
programmed to any voltage from 0.69dc to 5.5Vdc by
connecting a resistor between the Trim and GND pins of the
module. Certain restrictions apply on the output voltage set
point depending on the input voltage. These are shown in the
Output Voltage vs. Input Voltage Set Point Area plot in Fig. 44.
The Upper Limit curve shows that for output voltages of 0.9V
and lower, the input voltage must be lower than the maximum
of 14V. The Lower Limit curve shows that for output voltages of
3.3V and higher, the input voltage needs to be larger than the
minimum of 4.5V.
0
2
4
6
8
10
12
14
16
0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6
Output Voltage (V)
In
p
u
t V
o
lt
ag
e
(v
)
Lower Limit
Upper Limit
Figure 44. Output Voltage vs. Input Voltage Set Point
Area plot showing limits where the output voltage can
be set for different input voltages.
Without an external resistor between Trim and GND pins,
the output of the module will be 0.69Vdc. To calculate
the value of the trim resistor, Rtrim for a desired output
voltage, use the following equation:
( )
Ω






−
= k
Vo
Rtrim
69 . 0
9 . 6
Rtrim is the external resistor in kΩ
Vo is the desired output voltage.
Table 1 provides Rtrim values required for some common
output voltages.
Table 1
V
O, set
(V) Rtrim (KΩ)
0.7 690
1.0 22.26
1.2 13.53
1.5 8.519
1.8 6.216
2.5 3.812
3.3 2.644
5.0 1.601
By using a ±0.5% tolerance trim resistor with a TC of
±100ppm, a set point tolerance of ±1.5% can be
achieved as specified in the electrical specification.
Remote Sense
The 12V TLynx TM power modules have a Remote Sense
feature to minimize the effects of distribution losses by
regulating the voltage between the S+ and S– pins. The
voltage between the S– and GND pins of the module must
not drop below –0.2V. If Remote Sense is being used, the
voltage between S+ and S– cannot be more than 0.5V
larger than the voltage between VOUT and GND. Note
that the output voltage of the module cannot exceed the
specified maximum value. When the Remote Sense