Electronic Components Datasheet Search |
|
NCP2860 Datasheet(PDF) 9 Page - ON Semiconductor |
|
NCP2860 Datasheet(HTML) 9 Page - ON Semiconductor |
9 / 11 page NCP2860 http://onsemi.com 9 DETAILED OPERATING DESCRIPTION Internal Pass Transistor The NCP2860 incorporates a 0.5 W typical P−channel MOSFET pass transistor. The P−channel MOSFET requires no drive current and then compared to the PNP based regulators, this solution drastically reduces the quiescent current and associated losses. Shutdown Block The circuit turns into shutdown mode when the shutdown pin is in low state. In this mode, the internal biasing current sources are disconnected so that the pass transistor is off and the consumption reduced to a minimum value. Practically, the shutdown consumption is in the range of 10 nA. When this function is unused, “IN’’ is generally applied to the shutdown pin. Current Limitation The NCP2860 incorporates a short circuit protection that prevents the pass transistor current from exceeding 465 mA typically. The current limit is set to 220 mA during the start−up phase. Thermal Protection The thermal protection protects the die against excessive overheating. Practically, when the junction temperature exceeds 170°C for the 2.77 V option and 150°C for the 3.0 V option, an internal thermal sensor sends a logical signal to the shutdown block so that the circuit enters the shutdown mode. Once the die has cooled enough (typically 30°C), the circuit enters a new working phase. Output Voltage Setting a) The output voltage is set by internal resistor divider to 2.77 V for NCP2860DM277R2 device. The ”SET” pin must be grounded or pulled below 0.2 V. b) The output voltage can also be programmed to a different value for NCP2860DMADJR2G device. In this case a portion of the output voltage acquired by the external resistor divider must be applied to the ”SET” pin. Do not leave the ”SET” pin unconnected. If a (R1, R2) external resistors divider is used, then output voltage is given by equation: Vout = (1 + R1/R2) * Vref Therefore, as Vref typically equals 1.244 V: Vout = 1.244 * (1 + R1/R2). Now if R1 and R2 are high impedance resistors, the leakage current that is absorbed by the “SET’’ pin, may have to be taken into account as follows: Vout = [1.244 * (1 + R1/R2)] + (R1*Ilk) where Ilk is the “SET’’ pin leakage current. If the output voltage is directly applied to the “SET’’ pin, Vout = Vref = 1.244 V. OUT SET NCP2860 R1 R2 Vout Regulation The circuit incorporates a transconductance error amplifier. The error amplifier output varies in response to load and input voltage variations to control the pass transistor current so that the “OUT’’ pin delivers the wished voltage. No compensation capacitor is required. Fault Detection Circuitry The circuit detects when the input−output differential voltage is too low to ensure a correct load and line regulation at the output. The input−output differential threshold scales proportionally with the load current to be always just higher than the dropout. When the circuit detects a fault condition, an internal switch connects “FAULT’’ to ground. In normal operation, the “FAULT’’ terminal is an open−drain−N−channel MOSFET and if a pull−up resistor is connected between “OUT’’ and “FAULT’’, “FAULT’’ goes high. The pullup resistor is generally selected in the range of 100 k W to minimize the current consumption. Application Information It is recommended to use 2.2 mF capacitors on the input and on the output of the NCP2860. Capacitor type is not very critical. Simply the ESR should be lower than 0.5 W to ensure a stable operation over the temperature and output current ranges. It could be convenient to increase the capacitor size and its quality (lower ESR) only if it was necessary to further improve the noise performances, the Power Supply Rejection Ratio or the fast transient response. |
Similar Part No. - NCP2860 |
|
Similar Description - NCP2860 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List 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 |