- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄44982 > LT1776IS8#TR (LINEAR TECHNOLOGY CORP) 1 A SWITCHING REGULATOR, 230 kHz SWITCHING FREQ-MAX, PDSO8 PDF資料下載
參數(shù)資料
| 型號： | LT1776IS8#TR |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 1 A SWITCHING REGULATOR, 230 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封裝： | 0.150 INCH, PLASTIC, SO-8 |
| 文件頁數(shù)： | 4/20頁 |
| 文件大?。?/td> | 224K |
| 代理商： | LT1776IS8#TR |
12
LT1776
APPLICATIONS INFORMATION
WU
U
PAC = 1/2 VIN IOUT (tr + tf + 30ns) f
tr = (VIN/1.6)ns in high dV/dt mode
(VIN/0.16)ns in low dV/dt mode
tf = (VIN/1.6)ns (irrespective of dV/dt mode)
f = switching frequency
Total power dissipation of the die is simply the sum of
quiescent, DC and AC losses previously calculated.
PD(TOTAL) = PQ + PDC + PAC
Frequency Compensation
Loop frequency compensation is performed by connect-
ing a capacitor, or in most cases a series RC, from the
output of the error amplifier (VC pin) to ground. Proper
loop compensation may be obtained by empirical meth-
ods as described in detail in Application Note 19. Briefly,
this involves applying a load transient and observing the
dynamic response over the expected range of VIN and
ILOAD values.
As a practical matter, a second small capacitor, directly
from the VC pin to ground is generally recommended to
attenuate capacitive coupling from the VSW pin. A typical
value for this capacitor is 100pF. (See Switch Node Con-
siderations).
Switch Node Considerations
For maximum efficiency, switch rise and fall times are
made as short as practical. To prevent radiation and high
frequency resonance problems, proper layout of the com-
ponents connected to the IC is essential, especially the
power path. B field (magnetic) radiation is minimized by
keeping output diode, switch pin and input bypass capaci-
tor leads as short as possible. E field radiation is kept low
by minimizing the length and area of all traces connected
to the switch pin (VSW). A ground plane should always be
used under the switcher circuitry to prevent interplane
coupling.
However, remember that oscillator slowdown to achieve
short-circuit protection (discussed above) is dependent
on FB pin behavior, and this in turn, is sensitive to FB node
external impedance. Figure 2 shows the typical relation-
ship between FB divider Thevenin voltage and impedance,
and oscillator frequency. This shows that as feedback
network impedance increases beyond 10k, complete os-
cillator slowdown is not achieved, and short-circuit pro-
tection may be compromised. And as a practical matter,
the product of FB pin bias current and larger FB network
impedances will cause increasing output voltage error.
(Nominal cancellation for 10k of FB Thevenin impedance
is included internally.)
Thermal Considerations
Care should be taken to ensure that the worst-case input
voltage and load current conditions do not cause exces-
sive die temperatures. The packages are rated at 110
°C/W
for the 8-pin SO (S8) and 130
°C/W for 8-pin PDIP (N8).
Quiescent power is given by:
PQ = IIN VIN + IVCC VOUT
(This assumes that the VCC pin is connected to VOUT.)
Power loss internal to the LT1776 related to actual output
current is composed of both DC and AC switching losses.
These can be roughly estimated as follows:
DC switching losses are dominated by output switch “ON
voltage”, i.e.,
PDC = VON IOUT DC
VON = Output switch ON voltage, typically 1V at 500mA
IOUT = Output current
DC = ON duty cycle
AC switching losses are typically dominated by power lost
due to the finite rise time and fall time at the VSW node.
Assuming, for simplicity, a linear ramp up of both voltage
and current and a current rise/fall time equal to 15ns,
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LT1871IMS-7#PBF | SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO10 |
| LT1871IMS-7 | SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO10 |
| LT1871EMS-7#PBF | SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO10 |
| LT1871EMS-7 | SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO10 |
| LT1871EMS-7#TR | SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO10 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LT1777 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Low Noise Step-Down Switching Regulator |
| LT1777C | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Low Noise Step-Down Switching Regulator |
| LT1777CS | 功能描述:IC REG BUCK ADJ 0.7A 16SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 類型:升壓（升壓） 輸出類型:可調(diào)式 輸出數(shù):1 輸出電壓:1.24 V ~ 30 V 輸入電壓:1.5 V ~ 12 V PWM 型:電流模式，混合 頻率 - 開關(guān):600kHz 電流 - 輸出:500mA 同步整流器:無 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:8-SOIC |
| LT1777CS#PBF | 功能描述:IC REG BUCK ADJ 0.7A 16SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:250 系列:- 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:1.2V 輸入電壓:2.05 V ~ 6 V PWM 型:電壓模式 頻率 - 開關(guān):2MHz 電流 - 輸出:500mA 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:6-UFDFN 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:6-SON（1.45x1） 產(chǎn)品目錄頁面:1032 (CN2011-ZH PDF) 其它名稱:296-25628-2 |
| LT1777CS#TR | 功能描述:IC REG BUCK ADJ 0.7A 16SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 類型:升壓（升壓） 輸出類型:可調(diào)式 輸出數(shù):1 輸出電壓:1.24 V ~ 30 V 輸入電壓:1.5 V ~ 12 V PWM 型:電流模式，混合 頻率 - 開關(guān):600kHz 電流 - 輸出:500mA 同步整流器:無 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:8-SOIC |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。