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参数资料
| 型号： | LT1766IGN#TR |
| 厂商： | Linear Technology |
| 文件页数： | 20/30页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK ADJ 1.5A 16SSOP |
| 标准包装： | 2,500 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 1.2 V ~ 54 V |
| 输入电压： | 5.5 V ~ 60 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 200kHz |
| 电流 - 输出： | 1.5A |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-SSOP（0.154"，3.90mm 宽） |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 16-SSOP |
| 其它名称： | LT1766IGNTR |
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LT1766/LT1766-5
APPLICATIONS INFORMATION
SW RISE
SW FALL
10V/DIV
SWITCH NODE
VOLTAGE
2V/DIV
INDUCTOR
0.2A/DIV
CURRENT
AT I OUT = 0.1A
50ns/DIV
1766 F07
V IN = 40V
1μs/DIV
1766 F08
V OUT = 5V
L = 47μH
V OUT 2 ( I OUT / 36 )
( ) 9 ? ( ) 2 / 1 ( 1 )( 40 ) ( ) 3
( ) ( V OUT ) + t EFF ( 1 / 2 ) ( I OUT )( V IN )( f )
Figure 7. Switch Node Resonance
a >100MHz oscilloscope must be used, and waveforms
should be observed on the leads of the package. This
switch off spike will also cause the SW node to go below
ground. The LT1766 has special circuitry inside which
mitigates this problem, but negative voltages over 0.8V
lasting longer than 10ns should be avoided. Note that
100MHz oscilloscopes are barely fast enough to see the
details of the falling edge overshoot in Figure 7.
A second, much lower frequency ringing is seen during
switch off-time if load current is low enough to allow the
inductor current to fall to zero during part of the switch
off-time (see Figure 8). Switch and diode capacitance
resonate with the inductor to form damped ringing at 1MHz
to 10 MHz. This ringing is not harmful to the regulator
and it has not been shown to contribute signi?cantly to
EMI. Any attempt to damp it with a resistive snubber will
degrade ef?ciency.
THERMAL CALCULATIONS
Power dissipation in the LT1766 chip comes from four
sources: switch DC loss, switch AC loss, boost circuit cur-
rent, and input quiescent current. The following formulas
show how to calculate each of these losses. These formulas
assume continuous mode operation, so they should not
be used for calculating ef?ciency at light load currents.
Switch loss:
2
R SW I OUT
P SW =
V IN
Figure 8. Discontinuous Mode Ringing
Boost current loss:
P BOOST =
V IN
Quiescent current loss:
P Q = V IN ( 0 . 0015 ) + V OUT ( 0 . 003 )
R SW = Switch resistance (≈ 0.3) hot
t EFF = Effective switch current/voltage overlap time
= (t r + t f + t Ir + t If )
t r = (V IN /1.2)ns
t f = (V IN /1.7)ns
t Ir = t If = (I OUT /0.05)ns
f = Switch frequency
Example: with V IN = 40V, V OUT = 5V and I OUT = 1A:
P SW = ( 0.3 )( 1 ) 2 ( 5 ) + 97 ? 10 200 ? 10
40
= 0 . 04 + 0 . 388 = 0 . 43 W
P BOOST = ( 5 ) 2 ( 1 / 36 ) = 0 . 02 W
40
P Q = 40 ( 0 . 0015 ) + 5 ( 0 . 003 ) = 0 . 08 W
Total power dissipation in the IC is given by:
P TOT = P SW + P BOOST + P Q
= 0.43W + 0.02W + 0.08W = 0.53W
1766fc
20
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT1766IGN-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:5.5V to 60V 1.5A, 200kHz Step-Down Switching Regulator |
| LT1767 | 制造商:LINER 制造商全称:Linear Technology 功能描述:1.4A, 500kHz Step-Down Switching Regulator |
| LT1767-1.8 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Monolithic 1.5A, 1.25MHz Step-Down Switching Regulators |
| LT1767-2.5 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Monolithic 1.5A, 1.25MHz Step-Down Switching Regulators |
| LT1767-3.3 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Monolithic 1.5A, 1.25MHz Step-Down Switching Regulators |
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