Electronic Components Datasheet Search |
|
MAX8625AETD+ Datasheet(PDF) 11 Page - Maxim Integrated Products |
|
MAX8625AETD+ Datasheet(HTML) 11 Page - Maxim Integrated Products |
11 / 16 page High-Efficiency, Seamless Transition, Step-Up/Down DC-DC Converter ______________________________________________________________________________________ 11 or oscillation between the boost and buck modes as seen in other step-up/down converters. See the switch- ing waveforms for each of the three modes and transi- tion waveforms in the Typical Operating Characteristics section. Forced-PWM Mode Drive SKIP high to operate the MAX8625A in forced- PWM mode. In this mode, the IC operates at a constant 1MHz switching frequency with no pulse skipping. This scheme is desirable in noise-sensitive applications because the output ripple is minimized and has a pre- dictable noise spectrum. Forced PWM consumes higher supply current at light loads due to constant switching. Skip Mode Drive SKIP low to operate the MAX8625A in skip mode to improve light-load efficiency. In skip mode, the IC switches only as necessary to maintain the output at light loads, but still operates with fixed-frequency PWM at medium and heavy loads. This maximizes light-load efficiency and reduces the input quiescent current to 37µA (typ). Do not dynamically transition between skip and FPWM. The MAX8625A is not designed for dynamic transitions between FPWM and skip modes. Spikes of negative inductor current are possible when making these types of dynamic transitions. The magnitude of the spike depends on the load and output capacitance. The MAX8625A has no protection against these types of negative current spikes. Load Regulation and Transient Response During a load transient, the output voltage instantly changes due to the ESR of the output capacitors by an amount equal to their ESR times the change in load current ( ΔVOUT = RESR x ΔILOAD). The output voltage then deviates further based on the speed at which the loop compensates for the load step. Increasing the out- put capacitance reduces the output-voltage droop. See the Capacitor Selection section. The typical application circuit limits the output transient droop to less than 3%. See the Typical Operating Characteristics section. Soft-Start Soft-start prevents input inrush current during startup. Internal soft-start circuitry ramps the peak inductor cur- rent with an internal DAC in 8ms. Once the output reaches regulation, the current limit immediately jumps to the maximum threshold. This allows full load capabil- ity as soon as regulation is reached, even if it occurs before the 8ms soft-start time is complete. When using the MAX8625A at low input voltages (close to UVLO and < 3V), it is recommended that the ON pin should not be tied to the BATT or supply voltage node directly. The ON pin should be held low for > 1ms after power to the MAX8625A is applied before it is driven high for normal operation. Shutdown Drive ON low to place the MAX8625A in shutdown mode and reduce supply current to less than 1µA. During shutdown, OUT is disconnected from IN, and LX1 and LX2 are connected to GND. Drive ON high for normal operation. Fault and Thermal Shutdown The MAX8625A contains current-limit and thermal shut- down circuitry to protect the IC from fault conditions. When the inductor current exceeds the current limit (2A for the MAX8625A), the converter immediately enters phase 3 and an internal 100ms timer starts. The con- verter continues to commutate through the three phas- es, spending most of its time in phase 1 and phase 3. If the overcurrent event continues and the output is out of regulation for the duration of the 100ms timer, the IC enters shutdown mode and the output latches off. ON must then be toggled to clear the fault. If the overload is removed before the 100ms timer expires, the timer is cleared and the converter resumes normal operation. The thermal-shutdown circuitry disables the IC switching if the die temperature exceeds +165°C. The IC begins soft-start once the die temperature cools by 15°C. |
Similar Part No. - MAX8625AETD+ |
|
Similar Description - MAX8625AETD+ |
|
|
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 |