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參數(shù)資料
| 型號(hào)： | TK75018DCTL |
| 廠商： | TOKO INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHED CAPACITOR VOLTAGE CONVERTER WITH REGULATOR |
| 中文描述： | SWITCHED CAPACITOR CONVERTER, 35 kHz SWITCHING FREQ-MAX, PDIP8 |
| 封裝： | DIP-8 |
| 文件頁數(shù)： | 7/8頁 |
| 文件大?。?/td> | 91K |
| 代理商： | TK75018DCTL |
May 1999 TOKO, Inc.
Page 7
TK75018
PIN DESCRIPTIONS (CONT.)
INPUT CAPACITOR CHARGING PINS (CAP
+
/CAP
-
)
The positive driving pin of C
IN
(CAP +) charges the positive
node of the capacitor to V
IN
during t
CH
and pulls it down to
ground during t
DIS
. The negative driving pin of C
IN
(CAP -) pulls the negative node of the capacitor to ground
during t
CH
and is driven into the output during t
DIS
.
CIRCUIT GROUND (GND)
All potentials are referenced to this ground unless otherwise
noted.
OUTPUT VOLTAGE (V
OUT
)
In most applications, a capacitor must be placed from this
pin to ground to integrate the charge pulses delivered by
C
IN
. A minimum of ten times C
IN
is recommended. Since
the output voltage serves as the substrate inside the IC,
the design must ensure that this pin is never raised to a
higher potential than ground. This phenomenon will tend to
occur when a positive-supply-to-negative-supply load is
present at the converter output. A circuit, such as the one
shown in Figure 4, is recommended. Under normal
operation, the transistor will appear as a short circuit. But
the sink current will be cut off from the output pin if the
voltage starts to approach ground. The resistor is chosen
to keep the transistor saturated under all steady-state
operating conditions.
The equation below can be used to calculate the values of
the feedback resistors (R1 and R2) needed to achieve a
desired output voltage.
R
2
= R
1
+1 where R
1
≥
24 k
(
1.2 V
)
|V
|
CIN
+
+
LOAD
COUT
V+
IL
CAP +
GND
CAP -
V +
VOUT
REFERENCE VOLTAGE (V
ref
)
This pin provides a nominal 2.5 V buffered reference for
external use. Normal output current should be kept below
~160
μ
A.
OSCILLATOR PROGRAMMING (OSC)
This pin can be used to alter the nominal 25 kHz frequency
of the internal oscillator. An internal timing capacitor of
~150 pF is alternately charged during t
CH
and discharged
during t
DIS
with a 7
μ
A current source to fixed threshold
levels. Adding an external capacitor from the OSC pin to
ground will parallel the 150 pF capacitor to slow down the
clock period. Adding a small external capacitor from the
OSC pin to the CAP
+
pin will source/sink extra charge into/
out-of the internal timing capacitor to speed up the transition
between thresholds and thereby raise the oscillator
frequency. It is recommended that, in the latter
configuration, the capacitor be kept below ~30 pF.
Synchronization of multiple TK75018s can be accomplished
by adding pull-up resistors from the OSC pin to the
reference voltage and using an open collector from an
NPN transistor to provide the discharge. The NPN is then
driven by a clocking pulse, and the same pulse can be
used to drive multiple devices in the same configuration.
It is not recommended to pull the OSC pin high with a low-
impedance source. To synchronize and regulate with
multiple devices, an external reference can be used as the
reference point for the error voltage divider, thus allowing
the internal reference to be used as the pull-up point for the
OSC pin.
INPUT VOLTAGE (V
+
)
The input voltage is used to charge C
IN
during the time t
CH
during each clock period. C
IN
is then discharged into the
output capacitor during time t
DIS
. During t
CH
, the input
current will be approximately 2.2 times the output current.
During t
DIS
, the input current will be approximately 0.2
times the output current. A low ESR bypass capacitor will
average out the varying current seen by the input supply -
yielding an average input current of approximately 1.1
times the output current. The bypass capacitor should be
placed as near to the TK75018 as possible to disallow
inductive spikes on the supply rail of the IC. A minimum of
2
μ
F is recommended.
FIGURE 4: POSITIVE REFERENCED LOAD
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| TK75018MCTL | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:SWITCHED CAPACITOR VOLTAGE CONVERTER WITH REGULATOR |
| TK75018VCTL | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:SWITCHED CAPACITOR VOLTAGE CONVERTER WITH REGULATOR |
| TK75020 | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:ZVS RESONANT CONTROLLER |
| TK75020TL | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:ZVS RESONANT CONTROLLER |
| TK75020TL/75020 | 制造商:TOKO 制造商全稱:TOKO, Inc 功能描述:ZVS RESONANT CONTROLLER |
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