Datasheet LTC4365 (Analog Devices) - 10
| 制造商 | Analog Devices |
| 描述 | Overvoltage, Undervoltage and Reverse Supply Protection Controller |
| 页数 / 页 | 20 / 10 — APPLICATIONS INFORMATION. Overvoltage and Undervoltage Protection. Figure … |
| 修订版 | B |
| 文件格式/大小 | PDF / 1.1 Mb |
| 文件语言 | 英语 |
APPLICATIONS INFORMATION. Overvoltage and Undervoltage Protection. Figure 4. UV, OV Comparators Monitor 12V Supply
该数据表的模型线
- LTC4365CDDB#TRMPBF LTC4365CDDB#TRPBF LTC4365CDDB-1#TRMPBF LTC4365CDDB-1#TRPBF LTC4365CTS8#TRMPBF LTC4365CTS8#TRPBF LTC4365CTS8-1#TRMPBF LTC4365CTS8-1#TRPBF LTC4365HDDB#TRMPBF LTC4365HDDB#TRPBF LTC4365HDDB-1#TRMPBF LTC4365HDDB-1#TRPBF LTC4365HTS8#TRMPBF LTC4365HTS8#TRPBF LTC4365HTS8#WTRMPBF LTC4365HTS8#WTRPBF LTC4365HTS8-1#TRMPBF LTC4365HTS8-1#TRPBF LTC4365HTS8-1#WTRMPBF LTC4365HTS8-1#WTRPBF LTC4365IDDB#TRMPBF LTC4365IDDB#TRPBF LTC4365IDDB-1#TRMPBF LTC4365IDDB-1#TRPBF LTC4365ITS8#TRMPBF LTC4365ITS8#TRPBF LTC4365ITS8#WTRMPBF LTC4365ITS8#WTRPBF LTC4365ITS8-1#TRMPBF LTC4365ITS8-1#TRPBF LTC4365ITS8-1#WTRMPBF LTC4365ITS8-1#WTRPBF
文件文字版本
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APPLICATIONS INFORMATION
Figure 3 highlights the dependence of the gate drive on VIN
Overvoltage and Undervoltage Protection
and VOUT. When system power is first turned on (SHDN The LTC4365 provides two accurate comparators to moni- low to high, VOUT = 0V), gate drive is at a maximum for all tor for overvoltage (OV) and undervoltage (UV) conditions values of VIN. This helps prevent start-up problems into at VIN. If the input supply rises above the user adjustable heavy loads by ensuring that there is enough gate drive OV threshold, the gate of the external MOSFET is quickly to support the load. turned off, thus disconnecting the load from the input. As VOUT ramps up from 0V, the absolute value of the GATE Similarly, if the input supply falls below the user adjust- voltage remains fixed until VOUT is greater than the lower able UV threshold, the gate of the external MOSFET also of (VIN –1V) or 6V. Once VOUT crosses this threshold, is quickly turned off. Figure 4 shows a UV/OV application gate drive begins to increase up to a maximum of 9.8V for an input supply of 12V. (for VIN ≥ 12V). The curves of Figure 3 were taken with a GATE load of –1µA. If there were no load on GATE, the gate drive for each VIN would be slightly higher. LTC4365 12V VIN Note that when V R3 UV IN is at the lower end of the operating 2470k COMPARATOR range, the external N-channel MOSFET must be selected UV – with a corresponding lower threshold voltage. UVTH = 5V 25mV + R2 0.5V DISCHARGE GATE 215k WITH 50mA SINK 12 OV T = 25°C COMPARATOR IGATE = –1µA OV 10 OVTH = 18V + VIN = 30V R1 25mV 8 84.5k 0.5V – (V) 6 GATE 4365 F04 ∆V V 4 IN = 12V VIN = 5V
Figure 4. UV, OV Comparators Monitor 12V Supply
2 VIN = 3.3V VIN = 2.5V 0 0 3 6 9 12 15 The external resistive divider allows the user to select VOUT (V) 4365 F03 an input supply range that is compatible with the load at VOUT. Furthermore, the UV and OV inputs have very low
Figure 3. Gate Drive (GATE – VOUT) vs VOUT
leakage currents (typically < 1nA at 100°C), allowing for large values in the external resistive divider. In the applica- Table 1 lists some external MOSFETs compatible with tion of Figure 4, the load is connected to the supply only different VIN supply voltages. if VIN lies between 5V and 18V. In the event that VIN goes above 18V or below 5V, the gate of the external N-channel
Table 1. Dual MOSFETs for Various Supply Ranges
MOSFET is immediately discharged with a 50mA current
VIN MOSFET VTH(MAX) VGS(MAX) VDS(MAX)
sink, thus isolating the load from the supply. 2.5V SiB914 0.8V 5V 8V 3.3V Si5920 1.0V 5V 8V 5V Si7940 1.5V 8V 12V ≤30V Si4214 3.0V 20V 30V ≤60V Si9945 3.0V 20V 60V Rev. B 10 For more information www.analog.com Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Package Description Revision History Typical Application Related Parts
APPLICATIONS INFORMATION
Figure 3 highlights the dependence of the gate drive on VIN
Overvoltage and Undervoltage Protection
and VOUT. When system power is first turned on (SHDN The LTC4365 provides two accurate comparators to moni- low to high, VOUT = 0V), gate drive is at a maximum for all tor for overvoltage (OV) and undervoltage (UV) conditions values of VIN. This helps prevent start-up problems into at VIN. If the input supply rises above the user adjustable heavy loads by ensuring that there is enough gate drive OV threshold, the gate of the external MOSFET is quickly to support the load. turned off, thus disconnecting the load from the input. As VOUT ramps up from 0V, the absolute value of the GATE Similarly, if the input supply falls below the user adjust- voltage remains fixed until VOUT is greater than the lower able UV threshold, the gate of the external MOSFET also of (VIN –1V) or 6V. Once VOUT crosses this threshold, is quickly turned off. Figure 4 shows a UV/OV application gate drive begins to increase up to a maximum of 9.8V for an input supply of 12V. (for VIN ≥ 12V). The curves of Figure 3 were taken with a GATE load of –1µA. If there were no load on GATE, the gate drive for each VIN would be slightly higher. LTC4365 12V VIN Note that when V R3 UV IN is at the lower end of the operating 2470k COMPARATOR range, the external N-channel MOSFET must be selected UV – with a corresponding lower threshold voltage. UVTH = 5V 25mV + R2 0.5V DISCHARGE GATE 215k WITH 50mA SINK 12 OV T = 25°C COMPARATOR IGATE = –1µA OV 10 OVTH = 18V + VIN = 30V R1 25mV 8 84.5k 0.5V – (V) 6 GATE 4365 F04 ∆V V 4 IN = 12V VIN = 5V
Figure 4. UV, OV Comparators Monitor 12V Supply
2 VIN = 3.3V VIN = 2.5V 0 0 3 6 9 12 15 The external resistive divider allows the user to select VOUT (V) 4365 F03 an input supply range that is compatible with the load at VOUT. Furthermore, the UV and OV inputs have very low
Figure 3. Gate Drive (GATE – VOUT) vs VOUT
leakage currents (typically < 1nA at 100°C), allowing for large values in the external resistive divider. In the applica- Table 1 lists some external MOSFETs compatible with tion of Figure 4, the load is connected to the supply only different VIN supply voltages. if VIN lies between 5V and 18V. In the event that VIN goes above 18V or below 5V, the gate of the external N-channel
Table 1. Dual MOSFETs for Various Supply Ranges
MOSFET is immediately discharged with a 50mA current
VIN MOSFET VTH(MAX) VGS(MAX) VDS(MAX)
sink, thus isolating the load from the supply. 2.5V SiB914 0.8V 5V 8V 3.3V Si5920 1.0V 5V 8V 5V Si7940 1.5V 8V 12V ≤30V Si4214 3.0V 20V 30V ≤60V Si9945 3.0V 20V 60V Rev. B 10 For more information www.analog.com Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Package Description Revision History Typical Application Related Parts