TK71515AS Ver la hoja de datos (PDF) - Toko America Inc

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Fabricante

TK71515AS

LOW DROPOUT VOLTAGE REGULATOR

Toko America Inc  

TK715xxAS

DEFINITION AND EXPLANATION OF TECHNICAL TERMS

OUTPUT VOLTAGE (VOUT)

The output voltage is specified with VIN = (VOUT(TYP) + 1 V)

and IOUT = 5 mA.

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. 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.

CONTINUOUS OUTPUT CURRENT (IOUT)

Normal operating output current. This is limited by pack-

age power dissipation.

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 mVrms, 100 Hz superimposed on the

input voltage, where VIN = VOUT(TYP) + 2.0 V. The output

decoupling capacitor is set to 2.2 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.

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 re-

mains charged and the input is reduced to zero, or when

an external voltage higher than the input voltage is applied

to the output side.

LINE REGULATION (Line Reg)

REDUCTION OF OUTPUT NOISE

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(TYP) + 1 V to VIN = VOUT(TYP) + 6 V or VIN =

max 18 V.

LOAD REGULATION (Load Reg)

Although the architecture of the Toko regulators are de-

signed to minimize semiconductor noise, further reduction

can be achieved by the selection of external components.

The obvious solution is to increase the size of the output

capacitor. Please note that several parameters are af-

fected by the value of the capacitors and bench testing is

recommended when deviating from standard values.

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(TYP) +1 V. The load

regulation is specified under the output current step con-

dition 5 mA to 100 mA.

QUIESCENT CURRENT (IQ)

The quiescent current is the current which flows through

the ground terminal under no load conditions (IOUT = 0 mA).

GROUND CURRENT (IGND)

Ground current is the current which flows through the

ground pin(s). It is defined as IIN - IOUT, excluding control

current.

PACKAGE POWER DISSIPATION (PD)

This is the power dissipation level at which the thermal

sensor is activated. The IC contains an internal thermal

sensor which monitors the junction temperature. When the

junction temperature exceeds the monitor threshold of

150 °C, the IC is shut down. The junction temperature

rises as the difference between the input power (VIN x IIN)

and the output power (VOUT x IOUT) increases. The rate of

temperature rise is greatly affected by the mounting pad

configuration on the PCB, the board material, and the

ambient temperature. When the IC mounting has good

thermal conductivity, the junction temperature will be low

even if the power dissipation is great. When mounted on

the recommended mounting pad, the power dissipation of

the SOT23-3 is increased to 400 mW. For operation at

ambient temperatures over 25 °C, the power dissipation of

the SOT23-3 device should be derated at 3.2 mW/°C. To

Page 8

March 2001 TOKO, Inc.

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