APXH003A0X-SRZ_0910 Datasheet, PDF (13/23 Pages) Lineage Power Corporation – Pico TLynxTM 3A: Non-Isolated DC-DC Power Modules

Data Sheet
October 8, 2009
Pico TLynx^TM 3A: Non-isolated DC-DC Power Modules
2.4 – 5.5Vdc input; 0.6Vdc to 3.63Vdc output; 3A output current
module is ON. When transistor Q1 is turned ON, the
On/Off pin is pulled low, Q2 is turned off and the
internal PWM Enable signal is pulled high through the
100K internal pull-up resistor and the module is OFF.
VIN+
MODULE
100K
20K
I _ON/OFF
ON/OFF ₊
Q1
GND
V_ON/OFF
_
PWM Enable
Q2
20K
Figure 38. Circuit configuration for using positive
On/Off logic.
For negative logic On/Off modules, the circuit
configuration is shown in Fig. 39. The On/Off pin
should be pulled high with an external pull-up resistor
(suggested value for the 2.4V to 5.5Vin range is
3.6Kohms). When transistor Q1 is in the OFF state, the
On/Off pin is pulled high and the module is OFF. The
On/Off threshold for logic High on the On/Off pin
depends on the input voltage and its minimum value is
V_IN – 1.6V. To turn the module ON, Q1 is turned ON
pulling the On/Off pin low.
VIN+
MODULE
Rpullup
100K
ON/OFF
I _ON/OFF
+
V_ON/OFF
Q1
2.05K PWM Enable
20K
GND
_
Figure 39. 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.
Overtemperature 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 140^oC 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 Pico TLynx^TM 3A modules
can be programmed to any voltage from 0.6Vdc to
3.63Vdc 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. 40. The
Upper Limit curve shows that the entire output voltage
range is available with the maximum input voltage of
5.5V. The Lower Limit curve shows that for output
voltages of 1.8V and higher, the input voltage needs to
be larger than the minimum of 2.4V.
6
5
Upper Limit
4
3
Lower Limit
2
1
0
0.5
1
1.5
2
2.5
3
3.5
4
Output Voltage (V)
Figure 40. 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 0.6Vdc. To
calculate the value of the trim resistor, Rtrim for a
desired output voltage, use the following equation:
Rtrim
=
⎡
⎢
⎣
(Vo¹âˆ’^.20.6)^{⎥⎦⎤kΩ}
LINEAGE POWER
13