參數(shù)資料
型號(hào)： LT3689IUD-5#TRPBF
廠商： LINEAR TECHNOLOGY CORP
元件分類： 穩(wěn)壓器
英文描述： 1.95 A SWITCHING REGULATOR, 2160 kHz SWITCHING FREQ-MAX, PQCC16
封裝： 3 X 3 MM, LEAD FREE, PLASTIC, MO-220WEED-2, QFN-16
文件頁(yè)數(shù)： 10/32頁(yè)
文件大?。?/td> 2188K
代理商： LT3689IUD-5#TRPBF
LT3689/LT3689-5
18
3689fd
Table 4. Diode Vendors
PART NUMBER
VR
(V)
IAVE
(A)
VF AT IAVE
(mV)
On Semiconductor
MBRM120E
MBRM140
20
40
1
530
550
Diodes Inc.
B120
B130
B140
B0540W
B140HB
20
30
40
1
0.5
1
500
510
530
Ceramic Capacitors
Ceramic capacitors are small, robust and have very low
ESR. However, ceramic capacitors can cause problems
when used with the LT3689 due to their piezoelectric
nature. When in Burst Mode operation, the LT3689’s
switching frequency depends on the load current, and at
very light loads the LT3689 can excite the ceramic capaci-
tor at audio frequencies, generating audible noise. Since
the LT3689 operates at a lower current limit during Burst
Mode operation, the noise is typically very quiet. If this
noise is unacceptable, use a high performance tantalum
or electrolytic capacitor at the output.
Frequency Compensation
The LT3689 uses current mode control to regulate the
output, which simplifies loop compensation. In particular,
the LT3689 does not require the ESR of the output capaci-
tor for stability, allowing the use of ceramic capacitors to
achieve low output ripple and small circuit size. Figure 3
shows an equivalent circuit for the LT3689 control loop.
The error amp is a transconductance amplifier with finite
output impedance. The power section, consisting of the
modulator, power switch and inductor, is modeled as a
transconductance amplifier generating an output current
proportional to the voltage at the VC node. Note that the
output capacitor, C1, integrates this current, and that the
capacitor on the VC node (CC) integrates the error ampli-
fier output current, resulting in two poles in the loop. RC
provides a zero. With the recommended output capacitor,
theloopcrossoveroccursabovetheRCCCzero.Thissimple
model works well as long as the value of the inductor is
not too high and the loop crossover frequency is much
lower than the switching frequency. With a larger ceramic
capacitor (very low ESR), crossover may be lower and a
phaseleadcapacitor(CPL)acrossthefeedbackdividermay
improve the phase margin and transient response. Large
electrolytic capacitors may have an ESR large enough to
create an additional zero, and the phase lead may not be
necessary.
APPLICATIONS INFORMATION
Figure 3. Model for the Loop Response
–
+
–
+
800mV
VC
LT3689
GND
3689 F03
R1
OUT
ESR
ERROR
AMPLIFIER
CURRENT MODE
POWER STAGE
FB
R2
3M
RC
37k
CC
100pF
C1
gm =
300A/V
gm =
1.2A/V
+
CPL
0.7V
相關(guān)PDF資料
PDF描述
LT3689IMSE-5#TRPBF 1.95 A SWITCHING REGULATOR, 2160 kHz SWITCHING FREQ-MAX, PDSO16
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LT3724MPFE#TR SWITCHING CONTROLLER, 225 kHz SWITCHING FREQ-MAX, PDSO16
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LT3690EUFE#PBF 功能描述:IC REG BUCK SYNC ADJ 4A 26QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開(kāi)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(kāi)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(yè)面:1032 (CN2011-ZH PDF) 其它名稱:296-25628-2
LT3690EUFE#TRPBF 功能描述:IC REG BUCK SYNC ADJ 4A 26QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開(kāi)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(kāi)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
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