Electronic Components Datasheet Search |
|
MAX1572ETC180 Datasheet(PDF) 8 Page - Maxim Integrated Products |
|
MAX1572ETC180 Datasheet(HTML) 8 Page - Maxim Integrated Products |
8 / 11 page 800mA, 2MHz, PWM DC-to-DC Step-Down Converter with RESET 8 _______________________________________________________________________________________ MANUFACTURER PART VALUE (µH) RL (m Ω)ISAT (mA) SIZE (mm) SHIELDED Murata LQH32CN 2.2 97 790 2.5 x 3.2 x 2.0 No CDRH3D16 2.2 50 1200 3.8 x 3.8 x 1.8 Yes Sumida CDRH2D11 2.2 78 780 3.2 x 3.2 x 1.2 Yes D312F 2.2 170 1200 3.6 x 3.6 x 1.2 No TOKO D412F 2.2 140 1330 4.8 x 4.8 x 1.2 No Table 2. Recommended Inductors output and storing energy in the inductor’s magnetic field. The current-mode feedback system regulates the peak inductor current as a function of the output voltage error signal. Since the average inductor current is nearly the same as the peak inductor current (assuming that the inductor value is relatively high to minimize ripple current), the circuit acts as a switch-mode transconduc- tance amplifier. This pushes the output LC filter pole, normally found in a voltage-mode PWM, to a higher fre- quency. To preserve inner-loop stability and eliminate inductor staircasing, an internal slope-compensation ramp is summed into the main PWM comparator. During the second half of the switching cycle (off-time), the internal high-side P-channel MOSFET turns off and the internal low-side N-channel MOSFET turns on. Now the inductor releases the stored energy as its current ramps down while still providing current to the output. The output capacitor stores charge when the inductor current exceeds the load current and discharges when the inductor current is lower, smoothing the voltage across the load. Under overload conditions, when the inductor current exceeds the current limit, the high-side MOSFET is turned off and the low-side MOSFET remains on for the remainder of the cycle to let the inductor current ramp down. Pulse-Group Mode Pulse-group mode is used to minimize the supply cur- rent with a light load. In pulse-group mode, the IC shuts off most internal circuitry when VOUT is +0.8% above nominal regulation. When VOUT drops below +0.8% of the nominal regulation voltage, the IC powers up its cir- cuits and resumes switching. Pulse-Skip Mode Pulse-skip mode is also used to minimize the supply current with a light load. The difference between pulse- group and pulse-skip modes is that when VOUT rises above the +0.8% regulation point, pulse-group mode stops switching and completely turns off a number of circuits. Under the same conditions, pulse-skip mode stops switching but leaves all circuits on. The delay coming out of pulse-skip mode is shorter than with pulse-group mode. In pulse-skip mode, the output volt- age ripple is lower, and the load-transient response faster. However, the quiescent current is higher than in pulse-group mode. Forced-PWM Mode In forced-PWM mode, the MAX1572 operates at a con- stant 2MHz switching frequency without pulse skipping. This is desirable in noise-sensitive applications, since the output ripple is minimized and has a predictable noise spectrum. Forced-PWM mode requires higher supply current with light loads due to constant switching. 100% Duty-Cycle Operation The MAX1572 can operate at 100% duty cycle. In this state, the high-side P-channel MOSFET is turned on (not switching). This occurs when the input voltage is close to the output voltage. The dropout voltage is the voltage drop due to the output current across the on-resistance of the internal P-channel MOSFET (RDS(ON)P) and the inductor resistance (RL): VDROPOUT = IOUT × ( RDS(ON)P + RL ) RDS(ON)P is given in the Electrical Characteristics sec- tion. RL, for a few recommended inductors, is given in Table 2. Load-Transient Response/ Voltage Positioning The MAX1572 uses voltage positioning that matches the load regulation to the voltage droop seen during load transients. In this way, the output voltage does not overshoot when the load is removed, which results in the total output-voltage variation being half as wide as in a conventional design. Figure 2 shows an example of a voltage-positioned and a nonvoltage-positioned load transient. Additionally, the MAX1572 uses a wide-band- width feedback loop to respond more quickly to a load transient than regulators using conventional integrating feedback loops. The load line used to achieve voltage positioning is shown in Figure 3. This assumes a nominal operating point of 3.6V input at 300mA load. |
Similar Part No. - MAX1572ETC180 |
|
Similar Description - MAX1572ETC180 |
|
|
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 |