Datasheet

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PTH08T220W/221W
(Top View)
PTH08T220W , PTH08T221W
SLTS252K – NOVEMBER 2005 – REVISED JUNE 2009 ................................................................................................................................................... www.ti.com
TERMINAL FUNCTIONS
TERMINAL
DESCRIPTION
NAME NO.
V
I
2 The positive input voltage power node to the module, which is referenced to common GND.
V
O
5 The regulated positive power output with respect to GND.
This is the common ground connection for the V
I
and V
O
power connections. It is also the 0 V
dc
reference for the
GND 3, 4
control inputs.
The Inhibit pin is an open-collector/drain, negative logic input that is referenced to GND. Applying a low level
ground signal to this input disables the module ’ s output and turns off the output voltage. When the Inhibit control
is active, the input current drawn by the regulator is significantly reduced. If the Inhibit pin is left open-circuit, the
Inhibit
(1)
and
module produces an output whenever a valid input source is applied.
11
UVLO
This pin is also used for input undervoltage lockout (UVLO) programming. Connecting a resistor from this pin to
GND (pin 3) allows the ON threshold of the UVLO to be adjusted higher than the default value. For more
information, see the Application Information section.
A 0.05 W 1% resistor must be directly connected between this pin and pin7 ( – Sense) to set the output voltage to
a value higher than 0.69V. The temperature stability of the resistor should be 100 ppm/ ° C (or better). The
setpoint range for the output voltage is from 0.69V to 5.5V. If left open circuit, the output voltage will default to its
V
o
Adjust 8
lowest value. For further information, on output voltage adjustment see the related application note.
The specification table gives the preferred resistor values for a number of standard output voltages.
The sense input allows the regulation circuit to compensate for voltage drop between the module and the load.
+ Sense 6 The +Sense pin should always be connected to V
O
, either at the load for optimal voltage accuracy, or at the
module (pin 5).
The sense input allows the regulation circuit to compensate for voltage drop between the module and the load.
– Sense 7
For optimal voltage accuracy – Sense must be connected to GND (pin4) very close to the module (within 10cm).
This is an analog control input that enables the output voltage to follow an external voltage. This pin becomes
active typically 20 ms after the input voltage has been applied, and allows direct control of the output voltage
from 0 V up to the nominal set-point voltage. Within this range the module ' s output voltage follows the voltage at
Track 10
the Track pin on a volt-for-volt basis. When the control voltage is raised above this range, the module regulates
at its set-point voltage. The feature allows the output voltage to rise simultaneously with other modules powered
from the same input bus. If unused, this input should be connected to V
I
.
NOTE: Due to the undervoltage lockout feature, the output of the module cannot follow its own input voltage
during power up. For more information, see the related application note.
This input pin adjusts the transient response of the regulator. To activate the TurboTrans™ feature, a 1%, 50mW
resistor, must be connected between this pin and pin 6 (+Sense) very close to the module. For a given value of
output capacitance, a reduction in peak output voltage deviation is achieved by utililizing this feature. If unused,
TurboTrans™ 9
this pin must be left open-circuit. The resistance requirement can be selected from the TurboTrans resistor table
in the Application Information section. External capacitance must never be connected to this pin unless the
TurboTrans resistor value is a short, 0 Ω .
This input pin sychronizes the switching frequency of the module to an external clock frequency. The SmartSync
feature can be used to sychronize the switching fequency of multiple PTH08T220/221W modules, aiding EMI
SmartSync 1
noise suppression efforts. If unused, this pin should be connected to GND (pin3). For more information, please
review the Application Information section.
(1) Denotes negative logic: Open = Normal operation, Ground = Function active
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