參數(shù)資料
型號： LTC3112EFE#PBF
廠商： LINEAR TECHNOLOGY CORP
元件分類： 穩(wěn)壓器
英文描述： 12 A SWITCHING REGULATOR, 825 kHz SWITCHING FREQ-MAX, PDSO20
封裝： 4.40 MM, LEAD FREE, PLASTIC, TSSOP-20
文件頁數(shù)： 10/32頁
文件大小： 651K
代理商： LTC3112EFE#PBF
LTC3112
18
3112f
APPLICATIONS INFORMATION
Buck Mode Small Signal Model
The LTC3112 uses a voltage mode control loop to main-
tain regulation of the output voltage. An externally com-
pensated error amplier drives the COMP pin to generate
the appropriate duty cycle of the power switches. Use of
an external compensation network provides the exibility
for optimization of closed loop performance over the wide
variety of output voltages, switching frequencies, and
external component values supported by the LTC3112.
The small signal transfer function of the buck-boost con-
verter is different in the buck and boost modes of operation
and care must be taken to ensure stability in both operating
regions. When stepping down from a higher input voltage
to a lower output voltage, the converter will operate in buck
mode and the small signal transfer function from the error
amplier output, VCOMP, to the converter output voltage
is given by the following equation.
V
O
V
COMP BUCK MODE
= G
BUCK
1
+
s
2
πf
Z
1
+
s
2
πf
OQ
+
s
2
πf
O
2
The gain term, GBUCK, is comprised of two different
components: the gain of the pulse width modulator and
the gain of the power stage as given by the following ex-
pressions where VIN is the input voltage to the converter
in volts, f is the switching frequency in Hz, R is the load
resistance in ohms, and tLOW is the switch pin minimum
low time. A curve showing the switch pin minimum low time
can be found in the Typical Performance Characteristics
section of this datasheet. The parameter RS represents the
average series resistance of the power stage and can be
approximated as twice the average power switch resistance
plus the DC resistance of the inductor.
G
BUCK = GPWM GPOWER
G
PWM = 21– tLOW f
()
G
POWER =
V
INR
1– t
LOW f
() R+R
S
()
The buck mode gain is well approximated by the follow-
ing equation.
G
BUCK =
2
V
IN R
R
+R
S
2 V
IN
The buck mode transfer function has a single zero which
is generated by the ESR of the output capacitor. The zero
frequency, fZ, is given by the following expression where
RC and CO are the ESR (in ohms) and value (in farads) of
the output lter capacitor respectively.
f
Z =
1
2
πR
C CO
In most applications, an output capacitor with a very low
ESR is utilized in order to reduce the output voltage rip-
ple to acceptable levels. Such low values of capacitor ESR
result in a very high frequency zero and as a result the
zero is commonly too high in frequency to signicantly
impact compensation of the feedback loop.
The denominator of the buck mode transfer function ex-
hibits a pair of resonant poles generated by the LC ltering
of the power stage. The resonant frequency of the power
stage, fO, is given by the following expression where L is
the value of the inductor in henries.
f
O =
1
2
π
R
+R
S
LC
O R + RC
()
1
2
π
1
LC
O
The quality factor, Q, has a signicant impact on com-
pensation of the voltage loop since a higher Q factor
produces a sharper loss of phase near the resonant
frequency. The quality factor is inversely related to the
amount of damping in the power stage and is substantially
inuenced by the average series resistance of the power
stage, RS. Lower values of RS will increase the Q and result
in a sharper loss of phase near the resonant frequency
and will require more phase boost or lower bandwidth to
maintain an adequate phase margin.
Q
=
LC
O R + RC
() R+R
S
()
RR
CCO + L + CORS R + RC
()
LC
O
L
R
+ C
ORS
相關(guān)PDF資料
PDF描述
LTC3112EDHD#PBF 12 A SWITCHING REGULATOR, 825 kHz SWITCHING FREQ-MAX, PDSO16
LTC3112EDHD#TRPBF 12 A SWITCHING REGULATOR, 825 kHz SWITCHING FREQ-MAX, PDSO16
LTC3113EFE#PBF 16 A SWITCHING REGULATOR, 2000 kHz SWITCHING FREQ-MAX, PDSO20
LTC3113IDHD#TRPBF 16 A SWITCHING REGULATOR, 2000 kHz SWITCHING FREQ-MAX, PDSO16
LTC3113IFE#PBF 16 A SWITCHING REGULATOR, 2000 kHz SWITCHING FREQ-MAX, PDSO20
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LTC3112IDHD#PBF 功能描述:IC REG BUCK BST SYNC ADJ 16-DFN 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(jì)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
LTC3112IDHD#TRPBF 功能描述:IC REG BUCK BST SYNC ADJ 16-DFN 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(jì)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
LTC3112IFE#PBF 功能描述:IC REG BUCK BST SYNC ADJ 20TSSOP 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(jì)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
LTC3112IFE#TRPBF 功能描述:IC REG BUCK BST SYNC ADJ 20TSSOP 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(jì)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
LTC3113 制造商:LINER 制造商全稱:Linear Technology 功能描述:40V, 2A Synchronous Buck-Boost DC/DC
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