Os motores de busca de Datasheet de Componentes eletrônicos |
|
FAN2558SX Folha de dados(PDF) 6 Page - Fairchild Semiconductor |
|
FAN2558SX Folha de dados(HTML) 6 Page - Fairchild Semiconductor |
6 / 15 page FAN2558/FAN2559 PRODUCT SPECIFICATIONS 6 REV. 1.0.4 3/15/04 Functional Description Utilizing BiCMOS technology, the FAN2525/FAN2559 product family is optimized for use in compact battery pow- ered systems. These LDOs offer a unique combination of high ripple rejection, low noise, low power consumption, high tolerance for a variety of output capacitors, and less than 1µA “OFF” current. In the circuit, a differential current sense amplifier controls a series-pass P-Channel MOSFET to achieve high ripple rejection. A separate error amplifier com- pares the load voltage at the output with an onboard trimmed low voltage bandgap reference for output regulation. Thermal shutdown and current limit circuits protect the device under extreme conditions. When the device tempera- ture reaches 150°C, the output is disabled. When the device cools down by 10°C, it is re-enabled. The user can shut down the device using the Enable control pin at any time. The cur- rent limit circuit is trimmed, which leads to consistent power on /enable delays, and provides safe short circuit current densities even in narrow traces of the PCB. A carefully optimized control loop accommodates a wide range of ESR values in the output bypass capacitor, allowing the user to optimize space, cost, and performance require- ments. An Enable pin shuts down the regulator output to conserve power, reducing supply current to less than 1µA. The fixed-voltage FAN2559 has a noise bypass pin. Power Good is available as a diagnostic function to indicate that the output voltage has reduced within 5% of the nominal value. The six pin adjustable-voltage version utilizes pin 5 to con- nect to an external voltage divider which feeds back to the regulator error amplifier, thus setting the output voltage to the desired value. Applications Information External Capacitors – Selection The FAN2558/FAN2559 gives the user the flexibility to uti- lize a wide variety of capacitors compared to other LDOs. An innovative design approach offers significantly reduced sensitivity to ESR, which degrades regulator loop stability in older designs. While the improvements featured in the FAN2558/FAN2559 family greatly simplify the design task, capacitor quality still must be considered if the designer is to achieve optimal circuit performance. In general, ceramic capacitors offer superior ESR performance, and a smaller case size than tantalum capacitors. Input Capacitor An input capacitor of 2.2µF (nominal value) or greater, connected between the Input pin and Ground, placed in close proximity to the device, will improve transient response and ripple rejection. Higher values will further improve ripple rejection and transient response. An input capacitor is rec- ommended when the input source, either a battery or a regu- lated AC voltage, is located far from the device. Any good quality ceramic, tantalum, or metal film capacitor will give acceptable performance; however, in extreme cases capacitor surge current ratings may have to be considered. Output Capacitor An output capacitor is required to maintain regulator loop stability. Stable operation will be achieved with a wide vari- ety of capacitors with ESR values ranging from 0m Ω up to 400m Ω. Multilayer ceramic, tantalum or aluminum electro- lytic capacitors may be used. A nominal value of at least 1µF is recommended. Note that the choice of output capacitor affects load transient response, ripple rejection, and it has a slight effect on noise performance as well. An internal resistor of approximately 100 Ω is connected between VOUT and GND in shutdown mode, to discharge the output capacitor at a faster rate. Bypass Capacitor (FAN2559 Only) In the fixed-voltage configuration, connecting a capacitor between the bypass pin and ground can significantly reduce output noise. Values ranging from 0pF to 47nF can be used, depending on the sensitivity to output noise in the applica- tion. At the high-impedance Bypass pin, care must be taken in the PCB layout to minimize noise pickup, and capacitors must be selected to minimize current loading (leakage). Noise pickup from external sources can be considerable. Leakage currents into the Bypass pin will directly affect regulator accuracy and should be kept as low as possible; thus, high- quality ceramic and film types are recommended for their low leakage characteristics. Cost-sensitive applications not concerned with noise can omit this capacitor. |
Nº de peça semelhante - FAN2558SX |
|
Descrição semelhante - FAN2558SX |
|
|
Ligação URL |
Privacy Policy |
ALLDATASHEETPT.COM |
ALLDATASHEET é útil para você? [ DONATE ] |
Sobre Alldatasheet | Publicidade | Contato conosco | Privacy Policy | roca de Link | Lista de Fabricantes 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 |