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SLTS278G – NOVEMBER 2010 – REVISED MARCH 2009
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TERMINAL FUNCTIONS
TERMINAL
DESCRIPTION
NAME
NO.
VI
6,7,14,15 The positive input voltage power node to the module, which is referenced to common GND.
VO
10,11
The regulated positive power output with respect to GND.
This is the common ground connection for the VI and VO power connections. It is also the 0 Vdc reference for
GND
8,9,12,13
the 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
Inhibit(1) and
open-circuit, the module produces an output whenever a valid input source is applied.
21
UVLO
This pin is also used for input undervoltage lockout (UVLO) programming. Connecting a resistor from this pin
to GND (pin 13) 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 pin 4 (AGND) to set the output voltage
to a value higher than 0.7 V. The temperature stability of the resistor should be 100 ppm/°C (or better). The
setpoint range for the output voltage is from 0.7 V to 3.6 V. If left open circuit, the output voltage defaults to its
Vo Adjust
18
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
+ Sense
17
load. The +Sense pin should always be connected to VO, either at the load for optimal voltage accuracy, or at
the module (pin 11).
The sense input allows the regulation circuit to compensate for voltage drop between the module and the
– Sense
16
load. The –Sense pin should always be connected to GND, either at the load for optimal voltage accuracy, or
at the module (pin 13).
This is an analog control input that enables the output voltage to follow an external voltage. This pin becomes
active typically 25 ms after a valid 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
Track
20
voltage at 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 VI.
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%,
50 mW resistor, must be connected between this pin and pin 17 (+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
TurboTrans
19
feature. If unused, 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
.
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 frequency of multiple modules, aiding EMI noise
SmartSync
22
suppression efforts. The external synchronization frequency must be present before a valid input voltage is
present, or before the release of inhibit control. If unused, this pin MUST be connected to GND. For more
information, please review the Application Information section.
When two modules are connected together to share load current one must be configured as the MASTER and
the other as the SLAVE. This pin is used to configure the module as either MASTER or SLAVE. To configure
CONFIG
1
the module as the MASTER, connect this pin to GND. To configure the module as the SLAVE, connect this
pin to VI (pin 6). When not sharing current, this pin should be connected to GND.
This pin is used when connecting two modules together to share load current. When two modules are sharing
Share
2
current the Share pin of both modules must be connected together. When not sharing current, this pin MUST
be left open (floating).
This pin is used when connecting two modules together to share load current. When two modules are sharing
Comp
3
current the Comp pin of both modules must be connected together. When not sharing current, this pin MUST
be left open (floating).
This pin is the internal analog ground of the module. This pin provides the return path for the VOAdjust resistor
AGND
4
(RSET). When two modules are sharing current the AGND pin of both modules must be connected together.
Also, when two modules are connected, RSET must be connected only on the MASTER module.
This pin is used when connecting two modules together to share load current. When two modules are sharing
CLKIO
5
current the CLKIO pin of both modules must be connected together. When not sharing current, this pin MUST
be left open (floating).
(1)
Denotes negative logic: Open = Normal operation, Ground = Function active
6
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