TK11811 データシートの表示（PDF） - Toko America Inc
部品番号
コンポーネント説明
メーカー
TK11811 Datasheet PDF : 8 Pages
| |||
TK11811
VOLTAGE ADJUSTMENT CIRCUIT
T
R
VOUT
VOUT 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8
R
0 12 k 22 k 33 k 56 k 82 k 150 k 330 k 560 k *
Note: The output voltage can be set between 1.9 V and 2.8 V with an external resistor connected between pins 4 and 6.
ADDITIONAL INFORMATION
APPLICATION INFORMATION
Maximize copper foil area connecting to all IC pins for
optimum performance. Place input and output bypass
capacitors close to the GND pin. For best transient behavior
and lowest output impedance use as large a capacitor
value as possible. The temperature coefficient of the
capacitance and Equivalent Series Resistant (ESR) should
be taken into account. These parameters can influence
power supply noise and ripple rejection. In extreme cases,
oscillation may occur. In order to maintain stability, the
output bypass capacitor value should be minimum 10 µF
in case of tantalum electrolytic or 15 µF in case of aluminum
electrolytic.
HANDLING MOLDED RESIN PACKAGES
All plastic molded packages absorb some moisture from
the air. If moisture absorption occurs prior to soldering the
device into the printed circuit board, increased separation
of the lead from the plastic molding may occur, degrading
the moisture barrier characteristics of the device. This
property of plastic molding compounds should not be
overlooked, particularly in the case of very small packages
where the plastic is very thin. In order to preserve the
original moisture barrier properties of the package, devices
are stored and shipped in moisture proof bags filled with
dry air. The bags should not be opened or damaged prior
to actual use of the devices. If this is unavoidable, the
devices should be stored in a low relative humidity
environment (40 to 65 %) or in an enclosed environment
with desiccant.
INDUCTOR NOTES
The output current and efficiency are largely dependant
upon the coil used. A coil with lower DC resistance is
generally better in efficiency than one with a higher DCR
(DC Resistance). The recommended TOKO 395KN-0369
AQ is 1:1 turns ratio transformer with an inductance of
110 µH and Toko 395KN-0370UG is 1:3 turns ratio
transformer with inductance of 60 µH:600 µH. These coils,
or equivalent, should be used. Smaller coils with higher
DCR will not perform as well as the above coil, and the
oscillator will not be stable.
FEEDBACK RC TIME CONSTANT
If a different coil is used other than the one mentioned, the
RC time constant of the feedback loop will need to be
adjusted for optimum performance. Generally, a lower
resistance will give more output current. In fact, R can be
zero; however, lower resistance will sacrifice efficiency at
low output currents as the quiescent current increases. If
the capacitance is increased beyond or below a certain
value, the oscillator will become unstable. The optimum
Page 6
January 1999 TOKO, Inc.
Share Link: 