參數(shù)資料
型號(hào)： LTC1142LCG-ADJ
廠商： LINEAR TECHNOLOGY CORP
元件分類(lèi)： 穩(wěn)壓器
英文描述： RADIATION HARDENED HIGH EFFICIENCY, 5 AMP SWITCHING REGULATORS
中文描述： 0.05 A SWITCHING CONTROLLER, 250 kHz SWITCHING FREQ-MAX, PDSO28
封裝： 0.209 INCH, PLASTIC, SSOP-28
文件頁(yè)數(shù)： 13/20頁(yè)
文件大小： 401K
代理商： LTC1142LCG-ADJ
13
LTC1142/LTC1142L/LTC1142HV
APPLICATIU
current. When a load step occurs, V
OUT
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
until the regulator loop adapts
to the current change and returns V
OUT
to its steady-
state value. During this recovery time V
OUT
can be
monitored for overshoot or ringing which would indicate
a stability problem. The Pin 27 (13) external components
shown in the Figure 1 circuit will prove adequate com-
pensation for most applications.
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 would require a 250
μ
s rise time,
limiting the charging current to about 200mA.
W
U
U
Efficiency Considerations
The percent efficiency of a switching regulator is equal to
the output power divided by the input power times 100%.
It is often useful to analyze individual losses to determine
what is limiting the efficiency and which change would
produce the most improvement. Percent efficiency can be
expressed as:
%Efficiency = 100% – (L1 + L2 + L3 + ...)
where L1, L2, etc., are the individual losses as a percent-
age of input power. (For high efficiency circuits only small
errors are incurred by expressing losses as a percentage
of output power.)
Although all dissipative elements in the circuit produce
losses, three main sources usually account for most of the
losses in LTC1142 circuits:
1. LTC1142 DC bias current
2. MOSFET gate charge current
3. I
2
R losses
1. The DC supply current is the current which flows into
V
IN
(pin 24 for the 3.3V section, Pin 10 for the 5V
section) less the gate charge current. For V
IN
= 10V the
LTC1142 DC supply current for each section is 160
μ
A
with no load, and increases proportionally with load up
to a constant 1.6mA after the LTC1142 has entered
continuous mode. Because the DC bias current is
drawn from V
IN
, the resulting loss increases with input
voltage. For V
IN
= 10V the DC bias losses are generally
less than 1% for load currents over 30mA. However, at
very low load currents the DC bias current accounts for
nearly all of the loss.
2. MOSFET gate charge current results from switching
the gate capacitance of the power MOSFETs. Each time
a MOSFET gate is switched from low to high to low
again, a packet of charge dQ moves from V
IN
to ground.
The resulting dQ/dt is a current out of V
IN
which is
typically much larger than the DC supply current. In
continuous mode, I
GATE(CHG)
= f (Q
N
+ Q
P
). The typical
gate charge for a 0.1
N-channel power MOSFET is
25nC, and for a P-channel about twice that value. This
results in I
GATE(CHG)
= 7.5mA in 100kHz continuous
operation, for a 2% to 3% typical mid-current loss with
V
IN
= 10V.
Note that the gate charge loss increases directly with
both input voltage and operating frequency. This is the
principal reason why the highest efficiency circuits
operate at moderate frequencies. Furthermore, it ar-
gues against using larger MOSFETs than necessary to
control I
2
R losses, since overkill can cost efficiency as
well as money!
3. I
2
R losses are easily predicted from the DC resistances
of the MOSFET, inductor, and current shunt. In continu-
ous mode the average output current flows through L
and R
SENSE
, but is “chopped” between the P-channel
and N-channel MOSFETs. If the two MOSFETs have
approximately the same R
DS(ON)
, then the resistance of
one MOSFET can simply be summed with the resis-
tances of L and R
SENSE
to obtain I
2
R losses. For
example, if each R
DS(ON)
= 0.1
, R
L
= 0.15
, and
R
SENSE
= 0.05
, then the total resistance is 0.3
. This
results in losses ranging from 3% to 12% as the output
current increases from 0.5A to 2A. I
2
R losses cause the
efficiency to roll off at high output currents.
相關(guān)PDF資料
PDF描述
LTC1142 OCTAL BUS TRANSCEIVER O.C. 20-SOIC 0 to 70
LTC1142CG OCTAL BUS TRANSCEIVER O.C. 20-PDIP 0 to 70
LTC1142L OCTAL BUS TRANSCEIVER O.C. 20-PDIP 0 to 70
LTC1142L-ADJ OCTAL BUS TRANSCEIVER O.C. 20-SO 0 to 70
LTC1142-ADJ RADIATION HARDENED HIGH EFFICIENCY, 5 AMP SWITCHING REGULATORS
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LTC1142LCG-ADJ#PBF 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:4,000 系列:- PWM 型:電壓模式 輸出數(shù):1 頻率 - 最大:1.5MHz 占空比:66.7% 電源電壓:4.75 V ~ 5.25 V 降壓:是 升壓:無(wú) 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-40°C ~ 85°C 封裝/外殼:40-VFQFN 裸露焊盤(pán) 包裝:帶卷 (TR)
LTC1142LCG-ADJ#TR 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:否 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 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(wú) 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤(pán) 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱(chēng):LM1771SSDX
LTC1142LCG-ADJ#TRPBF 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:4,000 系列:- PWM 型:電壓模式 輸出數(shù):1 頻率 - 最大:1.5MHz 占空比:66.7% 電源電壓:4.75 V ~ 5.25 V 降壓:是 升壓:無(wú) 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-40°C ~ 85°C 封裝/外殼:40-VFQFN 裸露焊盤(pán) 包裝:帶卷 (TR)
LTC1143 制造商:LINER 制造商全稱(chēng):Linear Technology 功能描述:Dual High Efficiency SO-16 Step-Down Switching Regulator Controllers
LTC1143CS 功能描述:IC REG CTRLR BUCK PWM CM 16-SOIC RoHS:否 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無(wú) 升壓:是 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤(pán) 包裝:帶卷 (TR)
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(xiě)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

*
*
*