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| 型号： | LT1766IGN#TR |
| 厂商： | Linear Technology |
| 文件页数： | 21/30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
Thermal resistance for the LT1766 packages is in?uenced
by the presence of internal or backside planes.
SSOP (GN16) package: With a full plane under the GN16
package, thermal resistance will be about 85°C/W.
TSSOP (exposed pad) package: With a full plane under
the TSSOP package, thermal resistance will be about
45°C/W.
To calculate die temperature, use the proper thermal
resistance number for the desired package and add in
worst-case ambient temperature:
T J = T A + ( θ JA ? P TOT )
When estimating ambient, remember the nearby catch
diode and inductor will also be dissipating power:
Die temperature can peak for certain combinations of V IN ,
V OUT and load current. While higher V IN gives greater
switch AC losses, quiescent and catch diode losses, a
lower V IN may generate greater losses due to switch DC
losses. In general, the maximum and minimum V IN levels
should be checked with maximum typical load current
for calculation of the LT1766 die temperature. If a more
accurate die temperature is required, a measurement of
the SYNC pin resistance (to GND) can be used. The SYNC
pin resistance can be measured by forcing a voltage no
greater than 0.5V at the pin and monitoring the pin cur-
rent over temperature in an oven. This should be done
with minimal device power (low V IN and no switching
(V C = 0V)) in order to calibrate SYNC pin resistance with
ambient (oven) temperature.
P DIODE =
( V F )( V IN – V OUT )(I LOAD )
V IN
Note: Some of the internal power dissipation in the IC,
due to BOOST pin voltage, can be transferred outside
of the IC to reduce junction temperature, by increasing
V F = Forward voltage of diode (assume 0.63V at 1A)
the voltage drop in the path of the boost diode D2 (see
P DIODE =
(0.63)( 40 – 5)(1)
40
= 0 . 55 W
Figure 9). This reduction of junction temperature inside
the IC will allow higher ambient temperature operation for
a given set of conditions. BOOST pin circuitry dissipates
P INDUCTOR = (I LOAD ) 2 (R L )
power given by:
R L = Inductor DC resistance (assume 0.1Ω)
P INDUCTOR (1) 2 (0.1) = 0.1W
P DISS ( BOOST ) =
V OUT ? (I SW / 36) ? V C 2
V IN
P DISS ( BOOST ) =
Onlyaportionofthetemperatureriseintheexternalinductor
and diode is coupled to the junction of the LT1766. Based
on empirical measurements the thermal effect on LT1766
junction temperature due to power dissipation in the external
inductor and catch diode can be calculated as:
Δ T J (LT1766) ≈ (P DIODE + P INDUCTOR )(10°C/W)
Using the example calculations for LT1766 dissipation, the
LT1766 die temperature will be estimated as:
T J = T A + ( θ JA ? P TOT ) + [10 ? (P DIODE + P INDUCTOR )]
With the GN16 package ( θ JA = 85°C/W), at an ambient
temperature of 60°C:
T J = 60 + (85 ? 0.53) + (10 ? 0.65) = 112°C
With the TSSOP package ( θ JA = 45°C/W), at an ambient
temperature of 60°C:
T J = 60 + (45 ? 0.53) + (10 ? 0.65) = 90°C
Typically V C2 (the boost voltage across the capacitor C2)
equals Vout. This is because diodes D1 and D2 can be
considered almost equal, where:
V C2 = V OUT – V FD2 – (–V FD1 ) = V OUT
Hence the equation used for boost circuitry power dissi-
pation given in the previous Thermal Calculations section
is stated as:
V OUT ? (I SW / 36) ? V OUT
V IN
Here it can be seen that boost power dissipation increases
as the square of V OUT . It is possible, however, to reduce V C2
below V OUT to save power dissipation by increasing the
voltage drop in the path of D2. Care should be taken that
V C2 does not fall below the minimum 3.3V boost voltage
required for full saturation of the internal power switch.
1766fc
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相关代理商/技术参数 |
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|---|---|
| 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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