- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄377765 > LTC1875EGN (LINEAR TECHNOLOGY CORP) 15mA Quiescent Current 1.5A Monolithic Synchronous Step-Down Regulator PDF資料下載
參數(shù)資料
| 型號(hào)： | LTC1875EGN |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 15mA Quiescent Current 1.5A Monolithic Synchronous Step-Down Regulator |
| 中文描述： | 3 A SWITCHING REGULATOR, 605 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封裝： | 0.150 INCH, PLASTIC, SSOP-16 |
| 文件頁數(shù)： | 14/20頁 |
| 文件大小： | 257K |
| 代理商： | LTC1875EGN |
14
LTC1875
1875f
To avoid the LTC1875 from exceeding the maximum
junction temperature, the user will need to do some
thermal analysis. The goal of the thermal analysis is to
determine whether the power dissipated exceeds the
maximum junction temperature of the part. Normally,
some iterative calculation is required to determine a rea-
sonably accurate value. The temperature rise is given by:
T
R
= P
θ
JA
where P is the power dissipated by the regulator and
θ
JA
is the thermal resistance from the junction of the die to the
ambient temperature.
The junction temperature is given by:
T
J
= T
A
+ T
R
where T
A
is the ambient temperature. Because the power
transistor R
DS(ON)
is a function of temperature, it is
usually necessary to iterate 2 to 3 times through the
equations to achieve a reasonably accurate value for the
junction temperature.
As an example, consider the LTC1875 in dropout at an
input voltage of 3V, a load current of 0.8A and an ambient
temperature of 70
°
C. From the typical performance graph
of switch resistance, the R
DS(ON)
of the P-channel switch
at 70
°
C is 0.35
. Therefore, power dissipated by the IC is:
P = I
2
R
DS(ON)
= 0.224W
For the SSOP package, the
θ
JA
is 110
°
C/W. Thus the
junction temperature of the regulator is:
T
J
= 70
°
C + (0.224)(110) = 95
°
C
However, at this temperature, the R
DS(ON)
is actually 0.4
.
Therefore:
T
J
= 70
°
C + (0.256)(140) = 98
°
C
which is below the maximum junction temperature of
125
°
C.
Note that at higher supply voltages, the junction tempera-
ture is lower due to reduced switch resistance (R
DS(ON)
).
Checking Transient Response
The regulator loop response can be checked by looking at
the load transient response. Switching regulators take
several cycles to respond to a step in load current. When
a load step occurs, V
OUT
immediately shifts by an amount
equal to (
I
LOAD
ESR), where ESR is the effective series
resistance of C
OUT
.
I
LOAD
also begins to charge or
discharge C
OUT
, generating a feedback error signal. The
regulator loop then acts to return V
OUT
to its steady-state
value. During this recovery time, V
OUT
can be monitored
for overshoot or ringing that would indicate a stability
problem. The I
TH
pin can be used for external compensa-
tion as shown in Figure 9. (The capacitor, C
C2
, is typically
needed for noise decoupling.)
A second, more severe transient is caused by switching in
loads with large (>1
μ
F) supply bypass capacitors. The
discharged bypass capacitors are effectively put in parallel
with C
OUT
, causing a rapid drop in V
OUT
. No regulator can
deliver enough current to prevent this problem if the load
switch resistance is low and it is driven quickly. The only
solution is to limit the rise time of the switch drive so that
the load rise time is limited to approximately (25 C
LOAD
).
Thus, a 10
μ
F capacitor charging to 3.3V would require a
250
μ
s rise time, limiting the charging current to about
130mA.
APPLICATIOU
W
U
U
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LTC1877 | High Efficiency Monolithic Synchronous Step-Down Regulator(高效率,單片同步步降穩(wěn)壓器) |
| LTC1878 | High Efficiency Monolithic Synchronous Step-Down Regulator(高效率,單片同步步降穩(wěn)壓器) |
| LTC1911-15 | Low Noise, High Efficiency, Inductorless Step-Down DC/DC Converter |
| LTC1911EMS8-1.5 | Low Noise, High Efficiency, Inductorless Step-Down DC/DC Converter |
| LTC1911EMS8-1.8 | Low Noise, High Efficiency, Inductorless Step-Down DC/DC Converter |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC1875EGN#PBF | 功能描述:IC REG BUCK SYNC ADJ 1.5A 16SSOP 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: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)品目錄頁面:1032 (CN2011-ZH PDF) 其它名稱:296-25628-2 |
| LTC1875EGN#TR | 功能描述:IC REG BUCK SYNC ADJ 1.5A 16SSOP 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:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:1.2V，1.5V，1.8V，2.5V 輸入電壓:2.7 V ~ 20 V PWM 型:- 頻率 - 開關(guān):- 電流 - 輸出:50mA 同步整流器:是 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬）裸露焊盤 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:10-MSOP 裸露焊盤 |
| LTC1875EGN#TRPBF | 功能描述:IC REG BUCK SYNC ADJ 1.5A 16SSOP 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:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:1.2V，1.5V，1.8V，2.5V 輸入電壓:2.7 V ~ 20 V PWM 型:- 頻率 - 開關(guān):- 電流 - 輸出:50mA 同步整流器:是 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬）裸露焊盤 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:10-MSOP 裸露焊盤 |
| LTC1876EG | 功能描述:IC REG CTRLR BST PWM CM 36-SSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 標(biāo)準(zhǔn)包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數(shù):1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱:LM1771SSDX |
| LTC1876EG#PBF | 功能描述:IC REG CTRLR BST PWM CM 36-SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 標(biāo)準(zhǔn)包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數(shù):1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱:LM1771SSDX |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。