 |
Motor de Búsqueda de Datasheet de Componentes Electrónicos |
|
|
Motor de Búsqueda de Datasheet de Componentes Electrónicos |
|
A6250 Datasheet(PDF) 6 Page - EM Microelectronic - MARIN SA |
|
||||||||||||||||||||||||||||||
A6250 Datasheet(HTML) 6 Page - EM Microelectronic - MARIN SA |
|
|
6 / 13 page  6 A6250 Pin Description Pin Name Function 2 EN Push-pull active low enable output 3 RES Open drain active low reset output. RES must be pulled up to VOUTPUT even if unused 4 TCL Watchdog timer clear input signal 5 VSS GND terminal 12 INPUT Voltage regulator input 13 OUTPUT Voltage regulator output 14 R REXT input for RC oscillator tuning 15 VIN Voltage comparator input Table 5 Functional Description Voltage Regulator The A6250 has a 5 V ± 3%, 250 mA, low dropout voltage regulator. The low supply current (typ. 175 µA) makes the A6250 particularly suited to automotive systems then re- main energized 24 hours a day. The input voltage range is 2.3 V to 40 V for operation and the input protection in- cludes both reverse battery (20 V below ground) and load dump (positive transients up to 60 V). There is no reverse current flow from the OUTPUT to the INPUT when the INPUT equals VSS. This feature is important for systems which need to implement (with capacitance) a minimum power supply hold-up time in the event of power failure. To achieve good load regulation a 22 µF capacitor (or greater) is needed on the INPUT (see Fig. 8). Tantalum or aluminium electrolytics are adequate for the 22 µF capaci- tor; film types will work but are relatively expensive. Many aluminium electrolytics have electrolytes that freeze at about -30°C, so tantalums are recommended for opera- tion below -25°C. The important parameters of the 22 µF capacitor are an effective series resistance of ≤ 5 Ω and a resonant frequency above 500 kHz. A 10 µF capacitor (or greater) and a 100 nF capacitor are required on the OUTPUT to prevent oscillations due to in- stability. The specification of the 10 µF capacitor is as per the 22 µF capacitor on the INPUT (see previous para- graph). The A6250 will remain stable and in regulation with no ex- ternal load and the dropout voltage is typically constant as the input voltage fall to below its minimum level (see Table 2). These features are especially important in CMOS RAM keep-alive applications. Care must be taken not to exceed the maximum junction temperature (+125°C). The power dissipation within the A6250 is given by the formula: PTOTAL = (VINPUT - VOUTPUT) . IOUTPUT + (VINPUT) . ISS The maximum continuous power dissipation at a given temperature can be calculated using the formula: PMAX = (125°C - TA) / Rth(j-a) where Rth(j-a) is the thermal resistance from the junction to the ambient and is specified in Table 2. Note the R th(j-a) given in Table 2 assumes that the package is soldered to a PCB. The above formula for maximum power dissipation assumes a constant load (ie. ≥ 100 s). The transient ther- mal resistance for a single pulse is much lower than the continuous value. VIN Monitoring The power-on reset and the power-down reset are gener- ated as a response to the external voltage level on the VIN input. The external voltage level is typically obtained from a voltage divider as shown in Fig. 8. The user uses the ex- ternal voltage divider to set the desired threshold level for power-on reset and power-down reset in his system. The internal comparator reference voltage is typically 1.52 V. At power-up the reset output (RES) is held low (see Fig. 4). After INPUT reaches 3.36 V (and so OUTPUT reaches at least 3 V) and VIN becomes greater than VREF, the RES out- put is held low for an additional power-on-reset (POR) de- lay which is equal to the watchdog time T WD (typically 100 ms with an external resistor of 123 k Ω connected at R pin). The POR delay prevents repeated toggling of RES even if VIN and the INPUT voltage drops out and recovers. The POR delay allows the microprocessor’s crystal oscillator time to start and stabilize and ensures correct recognition of the reset signal to the microprocessor. The RES output goes active low generating the power-down reset whenever V IN falls below VREF. The sen- sitivity or reaction time of the internal comparator to the voltage level on VIN is typically 5 µs. Timer Programming The on-chip oscillator with an external resistor REXT con- nected between the R pin and VSS (see Fig. 8) allows the user to adjust the power-on reset (POR) delay, watchdog time TWD and with this also the closed and open time win- dows as well as the watchdog reset pulse width (TWD / 40). With REXT = 123 kΩ typical values are: - Power-on reset delay: T POR = 100 ms - Watchdog time: TWD = 100 ms - Closed window: TCW = 80 ms - Open window: TOW = 40 ms - Watchdog reset: TWDR = 2.5 ms Note the current consumption increases as the frequency increases. |
Número de pieza similar - A6250 |
|
Descripción similar - A6250 |
|
|
|
Enlace URL |
| Política de Privacidad |
| ALLDATASHEET.ES |
| ¿ALLDATASHEET es útil para Ud.? [ DONATE ] |
Todo acerca de Alldatasheet | Publicidad | Contáctenos | Política de Privacidad | Intercambio de Enlaces | 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 |
Spanish ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
