參數(shù)資料
型號(hào)： LTC1735IS-1#TRPBF
廠商： LINEAR TECHNOLOGY CORP
元件分類： 穩(wěn)壓器
英文描述： 3 A SWITCHING CONTROLLER, 550 kHz SWITCHING FREQ-MAX, PDSO16
封裝： 0.150 INCH, PLASTIC, SO-16
文件頁(yè)數(shù)： 17/28頁(yè)
文件大?。?/td> 343K
代理商： LTC1735IS-1#TRPBF
24
LTC1735-1
Design Example
As a design example, assume VIN = 12V (nominal), VIN =
22V (max), VOUT = 1.5V, IMAX = 12A and f = 300kHz,
RSENSE and COSC can immediately be calculated:
RSENSE = 50mV/12A = 0.042
COSC = 1.61(107)/(300kHz) – 11pF = 43pF
Assume a 1.2
H inductor and check the actual value of the
ripple current. The following equation is used :
I
V
fL
V
L
OUT
IN
=
()( )
–
1
The highest value of the ripple current occurs at the
maximum input and output voltages:
I
V
kHz
H
V
A
L =
=
15
300
1 2
1
15
22
39
.
(.
)
–
.
The maximum ripple current is 32% of maximum output
current, which is about right.
Next, verify the minimum on-time of 200ns is not violated.
The minimum on-time occurs at maximum VIN and mini-
mum VOUT.
t
V
Vf
V
kHz
ns
ON MIN
OUT
IN MAX
()
.
()
==
=
15
22 300
227
The power dissipation on the topside MOSFET can be
easily estimated. Choosing a Fairchild FDS6612A results
in; RDS(ON) = 0.03, CRSS = 80pF. At maximum input
voltage with T(estimated) = 50
°C:
P
V
CC
V
A
pF
kHz
mW
MAIN =
() +°
°
[]
()
+
() ()(
)(
)
=
15
22
12
1
0 005 50
25
0 03
1 7 22
12
80
300
568
2
.
( .
)(
–
)
.
Because the duty cycle of the bottom MOSFET is much
greater than the top, two larger MOSFETs must be paral-
leled. Choosing Fairchild FDS6680A MOSFETs yields a
parallel RDS(ON) of 0.0065. The total power dissipation
for both bottom MOSFETs, again assuming T = 50
°C, is:
P
VV
V
A
mW
SYNC =
() ( )
()
=
22
1 5
22
12
1 1 0 0065
959
2
–.
..
Thanks to current foldback, the bottom MOSFET dissipa-
tion in short circuit will be less than under full-load
conditions.
CIN is chosen for an RMS current rating of at least 6A at
temperature. COUT is chosen with an ESR of 0.01 for low
output ripple. The output ripple in continuous mode will be
highest at the maximum input voltage. The output voltage
ripple due to ESR is approximately:
VORIPPLE = RESR(IL) = 0.01(3.9A) = 39mVP-P
Since the output voltage is below 2.4V, the output resistive
divider will need to be sized to not only set the output
voltage but also to absorb the SENSE pins specified input
current.
R MAX
k
V
VV
k
124
08
24
15
21 3
()
.
.– .
.
=
=
Choosing 1% resistors: R1 = 21k and R2 = 18.7k yields an
output voltage of 1.512V.
PC Board Layout Checklist
When laying out the printed circuit board, the following
checklist should be used to ensure proper operation of the
LTC1735-1. These items are also illustrated graphically in
the layout diagram of Figure 12. Check the following in
your layout:
1. Are the signal and power grounds segregated? The
LTC1735-1 PGND pin should tie to the ground plane
close to the input capacitor(s). The SGND pin should
then connect to PGND and all components that connect
to SGND should make a single-point tie to the SGND
pin. The synchronous MOSFET source should connect
to the input capacitor(s) ground.
2. Does the VOSENSE pin connect directly to the feedback
resistors? The resistive divider R1, R2 must be con-
nected between the (+) plate of COUT and signal ground.
The 47pF capacitor from VOSENSE to SGND should be
as close as possible to the LTC1735-1. Be careful
locating the feedback resistors too far away from the
APPLICATIO S I FOR ATIO
WU
U
相關(guān)PDF資料
PDF描述
LTC2951IDDB-1#TRMPBF 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO8
LTC3105EDD#PBF SWITCHING REGULATOR, PDSO10
LTC3105EMS#PBF SWITCHING REGULATOR, PDSO12
LTC3105EMS#TRPBF SWITCHING REGULATOR, PDSO12
LTC3240EDC-3.3 0.45 A SWITCHED CAPACITOR REGULATOR, 1800 kHz SWITCHING FREQ-MAX, PDSO6
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LTC1736CG 功能描述:IC SW REG STEP-DOWN SYNC 24-SSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標(biāo)準(zhǔn)包裝:43 系列:- 應(yīng)用:控制器，Intel VR11 輸入電壓:5 V ~ 12 V 輸出數(shù):1 輸出電壓:0.5 V ~ 1.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:48-VFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:48-QFN（7x7） 包裝:管件
LTC1736CG#PBF 功能描述:IC SW REG STEP-DONW SYNC 24-SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標(biāo)準(zhǔn)包裝:43 系列:- 應(yīng)用:控制器，Intel VR11 輸入電壓:5 V ~ 12 V 輸出數(shù):1 輸出電壓:0.5 V ~ 1.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:48-VFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:48-QFN（7x7） 包裝:管件
LTC1736CG#TR 功能描述:IC REG SW SYNC STEPDWN HE 24SSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標(biāo)準(zhǔn)包裝:43 系列:- 應(yīng)用:控制器，Intel VR11 輸入電壓:5 V ~ 12 V 輸出數(shù):1 輸出電壓:0.5 V ~ 1.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:48-VFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:48-QFN（7x7） 包裝:管件
LTC1736CG#TRPBF 功能描述:IC SW REG STEP-DONW SYNC 24-SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標(biāo)準(zhǔn)包裝:43 系列:- 應(yīng)用:控制器，Intel VR11 輸入電壓:5 V ~ 12 V 輸出數(shù):1 輸出電壓:0.5 V ~ 1.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:48-VFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:48-QFN（7x7） 包裝:管件
LTC1736IG 功能描述:IC REG SW SYNC STEPDWN HE 24SSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標(biāo)準(zhǔn)包裝:43 系列:- 應(yīng)用:控制器，Intel VR11 輸入電壓:5 V ~ 12 V 輸出數(shù):1 輸出電壓:0.5 V ~ 1.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:48-VFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:48-QFN（7x7） 包裝:管件
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。

采購(gòu)需求

(若只采購(gòu)一條型號(hào)，填寫一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

*型號(hào) *數(shù)量 廠商 批號(hào) 封裝
添加更多采購(gòu)

我的聯(lián)系方式

*
*
*