TK717xxS
DEFINITION AND EXPLANATION OF TECHNICAL TERMS
OUTPUT VOLTAGE (V
OUT
)
The output voltage is specified with V
IN
= (V
OUT(TYP)
+ 1 V)
and I
OUT
= 5 mA.
MAXIMUM OUTPUT CURRENT (I
OUT(MAX)
)
The rated output current is specified under the condition where the
output voltage drops 0.3 V below the value specified with I
OUT
=
5 mA. This input voltage is set to V
OUT(TYP)
+1 V, and the current
is pulsed to minimize temperature effect.
DROPOUT VOLTAGE (V
DROP
)
THERMAL SENSOR
The dropout voltage is the difference between the input
voltage and the output voltage at which point the regulator
starts to fall out of regulation. Below this value, the output
voltage will fall as the input voltage is reduced. It is
dependent upon the load current and the junction tempera-
ture.
LINE REGULATION (Line Reg)
Line regulation is the ability of the regulator to maintain a
constant output voltage as the input voltage changes. The
line regulation is specified as the input voltage is changed
from V
IN
= V
OUT
+ 1 V to V
IN
= V
OUT
+ 6 V.
LOAD REGULATION (Load Reg)
Load regulation is the ability of the regulator to maintain a
constant output voltage as the load current changes. It is a
pulsed measurement to minimize temperature effects with
the input voltage set to V
IN
= V
OUT
+1 V. The load regulation
is specified under two output current step conditions of 5 mA
to 100 mA and 5 mA to 200 mA.
QUIESCENT CURRENT (I
Q
)
The quiescent current is the current which flows through the
ground terminal under no load conditions (I
OUT
= 0 mA).
RIPPLE REJECTION RATIO (RR)
Ripple rejection is the ability of the regulator to attenuate the
ripple content of the input voltage at the output. It is
specified with 200 mV
RMS
, 400 Hz and 1 kHz superimposed
on the input voltage, where V
IN
= V
OUT
+ 1.5 V. The output
decoupling capacitor is set to 1.0 µF, the noise bypass
capacitor is set to 0.01 µF, and the load current is set to 10
GND
mA. Ripple rejection is the ratio of the ripple content of the
output vs. the input and is expressed in dB.
STANDBY CURRENT (I
STBY
)
Standby current is the current which flows into the regulator
when the output is turned off by the control function.
OVER CURRENT SENSOR
The overcurrent sensor protects the device if the output is
shorted to ground.
The thermal sensor protects the device if the junction
temperature exceeds the safe value (T
j
= 150 °C). This
temperature rise can be caused by extreme heat, excessive
power dissipation caused by large output voltage drops, or
excessive output current. The regulator will shut off when
the temperature exceeds the safe value. As the junction
temperature decreases, the regulator will begin to operate
again. Under sustained fault conditions, the regulator output
will oscillate as the device turns off then resets. Damage
may occur to the device under extreme fault conditions.
REVERSE VOLTAGE PROTECTION
Reverse voltage protection prevents damage due to the
output voltage being higher than the input voltage. This fault
condition can occur when the output capacitor remains
charged and the input is reduced to zero, or when an external
voltage higher than the input voltage is applied to the output
side. Toko’s regulators do not need an inherent diode
connected between the input and output.
VIN
TK717xxS
VOUT
October 2001 TOKO, Inc.
Page 7
TOKO [ TOKO, INC ]
