Electronic Components Datasheet Search |
|
MAX882 Datasheet(PDF) 13 Page - Maxim Integrated Products |
|
MAX882 Datasheet(HTML) 13 Page - Maxim Integrated Products |
13 / 16 page 5V/3.3V or Adjustable, Low-Dropout, Low IQ, 200mA Linear Regulators ______________________________________________________________________________________ 13 When operating from sources other than batteries, sup- ply-noise rejection and transient response can be improved by increasing the values of the input and out- put capacitors and employing passive filtering tech- niques. Do not use power supplies with ripple voltage exceeding 200mV at 100kHz. Overshoot and Transient Considerations The Typical Operating Characteristics section shows power-up, supply, and load-transient response graphs. On the load-transient graphs, two components of the output response can be observed: a DC shift from the output impedance due to the different load currents, and the transient response. Typical transients for step changes in the load current from 50mA to 250mA are 200mV. Increasing the output capacitor’s value attenu- ates transient spikes. During recovery from shutdown, overshoot is negligible if the output voltage has been given time to decay ade- quately. During power-up from VIN = 0V, overshoot is typically less than 1% of VOUT. Input-Output (Dropout) Voltage A regulator’s minimum input-output voltage differential (or dropout voltage) determines the lowest usable sup- ply voltage. In battery-powered systems, this deter- mines the useful end-of-life battery voltage. Because the MAX882/MAX883/MAX884 use a P-channel MOS- FET pass transistor, their dropout voltage is a function of RDS(ON) multiplied by the load current (see Electrical Characteristics). Quickly stepping up the input voltage from the dropout voltage can result in overshoot. Short-Term Battery Backup Using the MAX882 Figure 9 illustrates a scheme for implementing battery backup for 3.3V circuits using the MAX882. When the supply voltage drops below some user-specified value based on resistors R1 and R2, the standby function activates, turning off the MAX882’s output. Under these conditions, the backup battery supplies power to the load. Reverse current protection prevents the bat- tery from draining back through the regulator to the input. This application is limited to short-term battery backup for 3.3V circuits. The current drawn by the MAX882’s OUT pin at 3.3V during reverse current protection is typically 8µA. It should not be used with the MAX883 and MAX884, since the OFF pin is a logic input, and indeterminate inputs can cause the regulator to turn on intermittently, draining the battery. Reverse Battery Protection Reverse battery protection can be added by including an inexpensive Schottky diode between the battery input and the regulator circuit, as shown in Figure 7. However, the dropout voltage of the regulator will be increased by the forward voltage drop of the diode. For example, the forward voltage of a standard 1N5817 Schottky diode is typically 0.29V at 200mA. BACKUP BATTERY MAX882 CIN O.1 µF COUT 2.2 µF OUTPUT VOLTAGE INPUT VOLTAGE LBI SET STBY IN D2 R1 R2 OUT GND Figure 9. Short-Term Battery Backup Using the MAX882 |
Similar Part No. - MAX882 |
|
Similar Description - MAX882 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | 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 |