TK717 查看數據表（PDF） - Toko America Inc
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TK717 Datasheet PDF : 20 Pages
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TK717xxS
DEFINITION AND EXPLANATION OF TECHNICAL TERMS
OUTPUT VOLTAGE (VOUT)
The output voltage is specified with VIN = (VOUT(TYP) + 1 V)
and IOUT = 5 mA.
MAXIMUM OUTPUT CURRENT (IOUT(MAX))
The rated output current is specified under the condition
where the output voltage drops 0.9 times the value specified
with IOUT = 5 mA. This input voltage is set to VOUT(TYP) +1
V, and the current is pulsed to minimize temperature effect.
The output current decreases during low voltage operation.
DROPOUT VOLTAGE (VDROP)
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 (this is the point when the
output voltage decreases by 100 mV). Below this value, the
output voltage will fall as the input voltage is reduced. It is
dependent upon the load current and the junction temperature.
superimposed on the input voltage, where VIN = VOUT + 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 mA. Ripple rejection is the ratio of the ripple content
of the output vs. the input and is expressed in dB. Ripple
rejection can be improved by increasing the noise bypass
capacitor (However, the on/off response time will increase).
STANDBY CURRENT (ISTBY)
Standby current is the current into the regulator when the
output is turned off by the control function. It is measured
with an input voltage of 8 V.
OVER CURRENT SENSOR
The overcurrent sensor protects the device when there is
excessive output current. it also protects the device if the
output is accidentally shorted to ground.
THERMAL SENSOR
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 VIN = VOUT + 1 V to VIN = VOUT + 6 V. It is a pulsed
measurement to minimize temperature effects.
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 VIN = VOUT +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 (IQ)
The quiescent current is the current which flows through the
ground terminal under no load conditions (IOUT = 0 mA).
GROUND PIN CURRENT(IGND)
The ground pin current is the current which flows through the
GND terminal according to load current. It is measured by
(input current-output current).
The thermal sensor protects the device if the junction
temperature exceeds the safe value (Tj = 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. The maximum
reverse bias boltage is 6 V.
RIPPLE REJECTION RATIO (RR)
VIN
VOUT
TK717xxS
Ripple rejection is the ability of the regulator to attenuate the
ripple content of the input voltage at the output. It is
specified with 500 mVRMS, 100 Hz and 1 MHz signal
GND
Page 14
January 2002 TOKO, Inc.
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