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參數(shù)資料
| 型號： | LTC1503IS8-1.8 |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 基準(zhǔn)電壓源/電流源 |
| 英文描述： | High Efficiency Inductorless Step-Down DC/DC Converters |
| 中文描述： | 1-OUTPUT DC-DC REG PWR SUPPLY MODULE |
| 封裝： | 0.150 INCH, PLASTIC, SOP-8 |
| 文件頁數(shù)： | 8/12頁 |
| 文件大?。?/td> | 187K |
| 代理商： | LTC1503IS8-1.8 |
8
LTC1503-1.8/LTC1503-2
2ms/DIV
1503-1.8/2 F02b
LTC1503-2
C
SS
= 0nF
C
OUT
= 10
μ
F
R
LOAD
= 50
Capacitor Selection
For best performance, it is recommended that low ESR
capacitors be used for C
IN
and C
OUT
to reduce noise and
ripple. If the ESR of the output capacitor is too high
(>0.5
), both efficiency and output load regulation may
be degraded. The C
IN
and C
OUT
capacitors should be either
ceramic or tantalum and should be 10
μ
F or greater. If the
input source impedance is very low (<0.5
), C
IN
may not
be needed. Ceramic capacitors are recommended for the
flying caps C1 and C2 with values of 0.47
μ
F to 2.2
μ
F.
Smaller values may be used in low output current applica-
tions (e.g., I
OUT
< 10mA). For best performance choose
the same capacitance value for both C1 and C2.
Output Ripple
Normal LTC1503-X operation produces voltage ripple on
the V
OUT
pin. Output voltage ripple is required for the parts
to regulate. Low frequency ripple exists due to the hyster-
esis in the sense comparator and propagation delays in the
charge pump enable/disable circuits. High frequency ripple
is also present mainly from the ESR (equivalent series
resistance) in the output capacitor. Typical output ripple
(V
IN
= 3.6V) under maximum load is 25mV peak-to-peak
with a low ESR 10
μ
F output capacitor.
The magnitude of ripple voltage depends on several fac-
tors. High input voltages increase the output ripple since
more charge is delivered to C
OUT
per charging cycle. Large
output current load and/or a small output capacitor (<10
μ
F)
results in higher ripple due to higher output voltage dV/dt.
High ESR capacitors (ESR > 0.5
) on the output pin cause
high frequency voltage spikes on V
OUT
with every clock
cycle.
There are several ways to reduce the output voltage ripple
(see Figure 3). A larger C
OUT
capacitor (22
μ
F or greater)
will reduce both the low and high frequency ripple due to
the lower C
OUT
charging and discharging dV/dt and the
lower ESR typically found with higher value (larger case
size) capacitors. A low ESR ceramic output capacitor will
minimize the high frequency ripple, but will not reduce the
low frequency ripple unless a high capacitance value is
chosen. A reasonable compromise is to use a 10
μ
F to 22
μ
F
tantalum capacitor in parallel with a 1
μ
F to 3.3
μ
F ceramic
approximately 1.9V. Since the ramp rate on the SHDN/SS
pin controls the ramp rate on V
OUT
, the average inrush
current can be controlled through selection of C
SS
and
C
OUT
. For example, a 4.7nF capacitor on SHDN/SS results
in a 4ms ramp time from 0.35V to 1.9V on the pin. If C
OUT
is 10
μ
F, the 4ms V
REF
ramp time results in an average
C
OUT
charge current of only 5mA (see Figure 2c).
5
1
R
LOAD
C
SS
1503-1.8/2 F02a
V
CTRL
ON OFF
SHDN/SS
V
OUT
LTC1503-X
(a)
V
2V/DIV
V
1V/DIV
(b)
2ms/DIV
1503-1.8/2 F02b
LTC1503-2
C
SS
= 4.7nF
C
OUT
= 10
μ
F
R
LOAD
= 50
V
2V/DIV
V
1V/DIV
(c)
Figure 2. Shutdown/Soft-Start Operation
APPLICATIOU
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U
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| LTC1503IS8-2 | 功能描述:IC REG BUCK SWITCHD CAP 2V 8SOIC 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 |
| LTC1503IS8-2#PBF | 功能描述:IC REG BUCK SWITCHD CAP 2V 8SOIC 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: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 |
| LTC1503IS8-2#TR | 功能描述:IC REG BUCK SWITCHD CAP 2V 8SOIC 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 |
| LTC1503IS8-2#TRPBF | 功能描述:IC REG BUCK SWITCHD CAP 2V 8SOIC 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: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 |
| LTC1504ACS8 | 功能描述:IC REG BUCK SYNC ADJ 0.5A 8SOIC 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 |
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