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參數資料
| 型號： | LT1054MH |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Switched-Capacitor Voltage Converter with Regulator |
| 中文描述： | SWITCHED CAPACITOR REGULATOR, 25 kHz SWITCHING FREQ-MAX, MBCY8 |
| 封裝： | METAL CAN, TO-5, 8 PIN |
| 文件頁數： | 10/26頁 |
| 文件大?。?/td> | 444K |
| 代理商： | LT1054MH |
SLVS033F FEBRUARY 1990 REVISED NOVEMBER 2004
10
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
PRINCIPLES OF OPERATION
The voltage reference (V
ref
) output provides a 2.5-V reference point for use in LT1054-based regulator circuits. The
temperature coefficient (TC) of the reference voltage has been adjusted so that the TC of the regulated output voltage
is near zero. As seen in the typical performance curves, this requires the reference output to have a positive TC. This
nonzero drift is necessary to offset a drift term inherent in the internal reference divider and comparator network tied
to the feedback terminal. The overall result of these drift terms is a regulated output that has a slight positive TC at
output voltages below 5 V and a slight negative TC at output voltages above 5 V. For regulator feedback networks,
reference output current should be limited to approximately 60
μ
A. V
ref
draws approximately 100
μ
A when shorted
to ground and does not affect the internal reference/regulator. This terminal also can be used as a pullup for LT1054
circuits that require synchronization.
CAP+ is the positive side of input capacitor C
IN
and is driven alternately between V
CC
and ground. When driven to
V
CC
, CAP+ sources current from V
CC
. When driven to ground, CAP+ sinks current to ground. CAP is the negative
side of the input capacitor and is driven alternately between ground and V
OUT
. When driven to ground, CAP sinks
current to ground. When driven to V
OUT
, CAP sources current from C
OUT
. In all cases, current flow in the switches
is unidirectional, as should be expected when using bipolar switches.
OSC can be used to raise or lower the oscillator frequency or to synchronize the device to an external clock. Internally,
OSC is connected to the oscillator timing capacitor (C
t
≈
150 pF), which is charged and discharged alternately by
current sources of
±
7
μ
A, so that the duty cycle is approximately 50%. The LT1054 oscillator is designed to run in
the frequency band where switching losses are minimized. However, the frequency can be raised, lowered, or
synchronized to an external system clock if necessary.
The frequency can be increased by adding an external capacitor (C2 in Figure 15) in the range of 520 pF from CAP+
to OSC. This capacitor couples a charge into C
t
at the switch transitions. This shortens the charge and discharge
times and raises the oscillator frequency. Synchronization can be accomplished by adding an external pullup resistor
from OSC to V
ref
. A 20-k
pullup resistor is recommended. An open-collector gate or an npn transistor then can be
used to drive OSC at the external clock frequency as shown in Figure 15.
The frequency can be lowered by adding an external capacitor (C
1
in Figure 15) from OSC to ground. This increases
the charge and discharge times, which lowers the oscillator frequency.
C1
LT1054
VOUT
VREF
OSC
VCC
CAP
GND
CAP+
FB/SD
C2
VIN
Pin numbers shown are for the P package.
+
1
2
3
4
8
7
6
5
Figure 15. External-Clock System
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| LT1054MJ8 | 功能描述:IC REG SWITCHD CAP DBL INV 8-DIP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關穩(wěn)壓器 系列:- 設計資源:Design Support Tool 標準包裝:1 系列:- 類型:升壓（升壓） 輸出類型:固定 輸出數:1 輸出電壓:3V 輸入電壓:0.75 V ~ 2 V PWM 型:- 頻率 - 開關:- 電流 - 輸出:100mA 同步整流器:是 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:SOT-23-5 細型，TSOT-23-5 包裝:剪切帶 (CT) 供應商設備封裝:TSOT-23-5 其它名稱:AS1323-BTTT-30CT |
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| LT1055CH | 制造商:Linear Technology 功能描述:OP Amp Single GP ±20V 8-Pin TO-5 制造商:Linear Technology 功能描述:OP Amp Single GP 20V 8-Pin TO-5 |
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