- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄377720 > LT1977IFE (LINEAR TECHNOLOGY CORP) High Voltage 1.5A, 500kHz Step-Down Switching Regulator with 100uA Quiescent Current PDF資料下載
參數(shù)資料
| 型號： | LT1977IFE |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | High Voltage 1.5A, 500kHz Step-Down Switching Regulator with 100uA Quiescent Current |
| 中文描述： | 3.5 A SWITCHING REGULATOR, 575 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封裝： | 4.4 MM, PLASTIC, TSSOP-16 |
| 文件頁數(shù)： | 12/24頁 |
| 文件大?。?/td> | 288K |
| 代理商： | LT1977IFE |
LT1977
12
1977f
APPLICATIOU
triangular with a typical value of 200mA
RMS
. The formula
to calculate this is:
Output capacitor ripple current (RMS)
V
( )( )(
W
U
U
I
V
V
RIPPLE RMS
OUT
IN
OUT
IN
(
)
.
–
)
=
(
)(
)
=
0 29
12
I
P-P
CERAMIC CAPACITORS
Higher value, lower cost ceramic capacitors are now
becoming available. They are generally chosen for their
good high frequency operation, small size and very low
ESR (effective series resistance). Low ESR reduces output
ripple voltage but also removes a useful zero in the loop
frequency response, common to tantalum capacitors. To
compensate for this a resistor R
C
can be placed in series
with the V
C
compensation capacitor C
C
(Figure 10). Care
must be taken however since this resistor sets the high
frequency gain of the error amplifier including the gain at
the switching frequency. If the gain of the error amplifier
is high enough at the switching frequency output ripple
voltage (although smaller for a ceramic output capacitor)
may still affect the proper operation of the regulator. A
filter capacitor C
F
in parallel with the R
C
/C
C
network, along
with a small feedforward capacitor C
FB
, is suggested to
control possible ripple at the V
C
pin. The LT1977 can be
stabilized using a 100
μ
F ceramic output capacitor and V
C
component values of C
C
= 1500pF, R
C
= 10k, C
F
= 330pF
and C
FB
= 10pF.
OUTPUT RIPPLE VOLTAGE
Figure 3 shows a typical output ripple voltage waveform
for the LT1977. Ripple voltage is determined by the
impedance of the output capacitor and ripple current
through the inductor. Peak-to-peak ripple current through
the inductor into the output capacitor is:
I
V
V
V
V
)( )( )
OUT
IN
OUT
IN
P-P
=
(
)
(
–
For high frequency switchers the ripple current slew rate
is also relevant and can be calculated from:
di
dt
V
L
IN
=
Peak-to-peak output ripple voltage is the sum of a triwave
created by peak-to-peak ripple current times ESR and a
square wave created by parasitic inductance (ESL) and
ripple current slew rate. Capacitive reactance is assumed
to be small compared to ESR or ESL.
V
I
ESR
)(
ESLdi
dt
RIPPLE
=
(
)
+
(
)
P-P
Example: with V
IN
= 12V, V
OUT
= 3.3V, L = 15
μ
H, ESR =
0.08
, ESL = 10nH:
I
P-P
=
(
e
)
( )
12
15
e
(
)
=
=
=
3 3 12 3 3
6 500 3
0 319
.
6
0 8 6
.
.
– .
–
e
A
di
dt
e
V
RIPPLE
= (0.319A)(0.08) + (10e – 9)(0.8e6)
= 0.026 + 0.008 = 34mV
P-P
MAXIMUM OUTPUT LOAD CURRENT
Maximum load current for a buck converter is limited by
the maximum switch current rating (I
PK
). The minimum
specified current rating for the LT1977 is 1.5A. Unlike
most current mode converters, the LT1977 maximum
switch current limit does not fall off at high duty cycles.
Most current mode converters suffer a drop off of peak
switch current for duty cycles above 50%. This is due to
the effects of slope compensation required to prevent
subharmonic oscillations in current mode converters.
(For detailed analysis, see Application Note 19.)
Figure 3. LT1977 Ripple Voltage Waveform
V
10mV/DIV
100
μ
F
75m
TANTALUM
V
10mV/DIV
100
μ
F
CERAMIC
V
10V/DIV
V
IN
= 12V
V
OUT
= 3.3V
I
L
500ns/DIV
1977 F03
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LT1990 | 250V Input Range G = 1, 10, Micropower, Difference Amplifier |
| LT1990ACS8 | 250V Input Range G = 1, 10, Micropower, Difference Amplifier |
| LT1990AIS8 | 250V Input Range G = 1, 10, Micropower, Difference Amplifier |
| LT1990CS8 | 250V Input Range G = 1, 10, Micropower, Difference Amplifier |
| LT1990IS8 | 250V Input Range G = 1, 10, Micropower, Difference Amplifier |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LT1977IFE#PBF | 功能描述:IC REG BUCK ADJ 1.5A 16TSSOP 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:- 設(shè)計資源:Design Support Tool 標(biāo)準(zhǔn)包裝:1 系列:- 類型:升壓（升壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:3V 輸入電壓:0.75 V ~ 2 V PWM 型:- 頻率 - 開關(guān):- 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(xì)型，TSOT-23-5 包裝:剪切帶 (CT) 供應(yīng)商設(shè)備封裝:TSOT-23-5 其它名稱:AS1323-BTTT-30CT |
| LT1977IFE#PBF | 制造商:Linear Technology 功能描述:DC-DC CONVERTER BUCK 500KHZ 制造商:Linear Technology 功能描述:DC-DC CONVERTER, BUCK, 500KHZ, TSSOP-16 |
| LT1977IFE#TR | 功能描述:IC REG BUCK ADJ 1.5A 16TSSOP 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:- 設(shè)計資源:Design Support Tool 標(biāo)準(zhǔn)包裝:1 系列:- 類型:升壓（升壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:3V 輸入電壓:0.75 V ~ 2 V PWM 型:- 頻率 - 開關(guān):- 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(xì)型，TSOT-23-5 包裝:剪切帶 (CT) 供應(yīng)商設(shè)備封裝:TSOT-23-5 其它名稱:AS1323-BTTT-30CT |
| LT1977IFE#TRPBF | 功能描述:IC REG BUCK ADJ 1.5A 16TSSOP 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:- 設(shè)計資源:Design Support Tool 標(biāo)準(zhǔn)包裝:1 系列:- 類型:升壓（升壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:3V 輸入電壓:0.75 V ~ 2 V PWM 型:- 頻率 - 開關(guān):- 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(xì)型，TSOT-23-5 包裝:剪切帶 (CT) 供應(yīng)商設(shè)備封裝:TSOT-23-5 其它名稱:AS1323-BTTT-30CT |
| LT1990 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Precision, 100μA Gain Selectable Amplifier |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。