数据搜索系统,热门电子元器件搜索 |
|
LT1172CK 数据表(PDF) 4 Page - Linear Technology |
|
LT1172CK 数据表(HTML) 4 Page - Linear Technology |
4 / 20 page 4 LT1170/LT1171/LT1172 SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS ∆IIN Supply Current Increase 25 35 mA/A ∆ISW During Switch On-Time f Switching Frequency 88 100 112 kHz q 85 115 kHz DCMAX Maximum Switch Duty Cycle q 85 92 97 % Shutdown Mode 3V ≤ VIN ≤ VMAX 100 250 µA Supply Current VC = 0.05V Shutdown Mode 3V ≤ VIN ≤ VMAX 100 150 250 mV Threshold Voltage q 50 300 mV Flyback Sense Delay Time (Note 5) 1.5 µs Transformer designs will tolerate much higher input voltages because leakage inductance limits rate of rise of current in the switch. These designs must be evaluated individually to assure that current limit is well controlled up to maximum input voltage. Boost mode designs are never protected against output shorts because the external catch diode and inductor connect input to output. Note 3: Measured with VC in hi clamp, VFB = 0.8V. ISW = 4A for LT1170, 2A for LT1171, and 1A for LT1172. Note 4: For duty cycles (DC) between 50% and 80%, minimum guaranteed switch current is given by ILIM = 3.33 (2 – DC) for the LT1170, ILIM = 1.67 (2 – DC) for the LT1171, and ILIM = 0.833 (2 – DC) for the LT1172. Note 5: Minimum input voltage for isolated flyback mode is 7V. VMAX = 55V for HV grade in fully isolated mode to avoid switch breakdown. Note 1: Absolute Maximum Ratings are those values beyond which the life of the device may be impaired. Note 2: Minimum effective switch “on” time for the LT1170/71/72 (in current limit only) is ≈ 0.6µs. This limits the maximum safe input voltage during an output shorted condition. Buck mode and inverting mode input voltage during an output shorted condition is limited to: VIN (max, output shorted) = 15V + buck and inverting mode R = Inductor DC resistance IL = 10A for LT1170, 5A for LT1171, and 2.5A for LT1172 Vf = Output catch diode forward voltage at IL t = 0.6 µs, f = 100kHz switching frequency Maximum input voltage can be increased by increasing R or Vf. External current limiting such as that shown in AN19, Figure 39, will provide protection up to the full supply voltage rating. C1 in Figure 39 should be reduced to 200pF. Switch Current Limit vs Duty Cycle* TEMPERATURE ( °C) –75 –25 25 50 150 1170/1/2 G02 –50 0 75 100 125 2.9 2.8 2.7 2.6 2.5 2.4 2.3 SWITCH CURRENT = 0A SWITCH CURRENT = IMAX Minimum Input Voltage Switch Saturation Voltage DUTY CYCLE (%) 0 16 12 8 4 0 40 1170/1/2 G01 20 30 50 60 70 80 90 100 25 °C 125 °C –55 °C 10 * DIVIDE VERTICAL SCALE BY TWO FOR LT1171, BY FOUR FOR LT1172. SWITCH CURRENT (A)* 0 8 1170/1/2 G03 1 2 3 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 45 6 7 25 °C 150 °C –55 °C 100 °C * DIVIDE CURRENT BY TWO FOR LT1171, BY FOUR FOR LT1172. (R)(IL) + Vf (t)(f) The q denotes the specifications which apply over the full operating tem- perature range, otherwise specifications are at TA = 25°C. VIN = 15V, VC = 0.5V, VFB = VREF, output pin open, unless otherwise noted. TYPICAL PERFOR A CE CHARACTERISTICS ELECTRICAL CHARACTERISTICS |
类似零件编号 - LT1172CK |
|
类似说明 - LT1172CK |
|
|
链接网址 |
隐私政策 |
ALLDATASHEETCN.COM |
ALLDATASHEET是否为您带来帮助? [ DONATE ] |
关于 Alldatasheet | 广告服务 | 联系我们 | 隐私政策 | 链接交换 | 制造商名单 All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |