| поискавой системы для электроныых деталей |
|
ACT88430 датащи(PDF) 36 Page - Qorvo, Inc |
|
|
|||||||||||||||||||||||||||||
ACT88430 датащи(HTML) 36 Page - Qorvo, Inc |
|
36 / 74 page ![]() Data Sheet Rev. G, August 2021 | Subject to change without notice 36 of 74 www.qorvo.com © 2020 Qorvo US, Inc. All rights reserved. Confidential ACT88430 Advanced PMU for Microcontrollers and Solid State Drive Applications ® and optimize transient performance over their full operating range. No compensation design is required; simply follow a few simple guide lines described below when choosing external components. Minimum On-Time The ACT88430 minimum on-time is 120ns. If the calculated on-time is less than 120ns with 2.25MHz operation, then the user must configure the output to switch at 1.125MHz. Setting I2C bits Bx_HalfFreq = 0 sets Fsw = 2.25MHz. Setting Bx_HalfFreq = 1 sets Fsw = 1.125MHz. The following equation calculates the on- time. ������������������������������������= ������������������������������������������������ ������������������������������������∗������������������������������������ Where Vout is the output voltage, Vin is the input voltage, and FSW is the switching frequency. BUCK1 Bypass Switch The ACT88430 provides a bypass mode for 3.3V systems. This allows the 3.3V input voltage to power the ACT88430 regulators and also be sequenced to the downstream loads. In bypass mode, the Buck1 P-ch FET acts as a switch and the N-ch FET is disabled. The bypass switch turns on the 3.3V rail with the programmed delay and softstart time. In bypass mode, the ACT88430 I2C registers are reconfigured to the following. 1. B1_PWR_GOOD register bit reconfigured to the output of the Soft Start ramp. When soft start is complete, this bit goes high to allow the sequencing of the other regulators to continue. B1_PWR_GOOD no longer reports the Buck1 output voltage status. It stays high as long as the bypass switch is enabled. 2. B1_ILIM bit is the output of the internal PMOS Current Detection circuit. This is set to 3A typical. If the bypass current exceeds the Internal PMOS Current Detection current, B1_ILIM triggers an IRQ output and gets latched in the ILIM_REG[0] if configured by the IRQ_nMASK. The B1_ILIM can also be masked with the B1_ILIM_FLTMSK register. B1_UV register bit reconfigured to the output of the Internal PMOS Current Shutdown circuit. This is set to 6A typical. If the bypass switch current exceeds 6A, limits the current which triggers an under voltage fault condition and moves the IC into the OVUVFLT state. This immediately shuts down all regulators including the bypass switch. The system restarts in 100ms, following the programmed startup sequencing. This fault can be masked with I2C bit UV_nMASK. This fault is latched in the UV_REG I2C bit. Shutdown due to overcurrent can also be masked via the I2C bit B1_PG_FLTMSK. B1_OV is disabled. There is no overvoltage detection circuitry on the output of the bypass switch. Input Capacitor Selection Each regulator requires a high quality, low-ESR, ceramic input capacitor. Note that even though each buck converter has separate input pins, all input pins must be connected to the same voltage potential. 10uF capacitors are typically suitable, but this value can be increased without limit. Smaller capacitor values can be used with lighter output loads. Choose the input capacitor value to keep the input voltage ripple less than 50mV. Vripple=������������������������������������������������∗������������������������������������������������������������������������������������∗�1−������������������������������������������������������������������������������������� ������������������������������������∗������������������������������������ Be sure to consider the capacitor’s DC bias effects and maximum ripple current rating when using capacitors smaller than 0805. A capacitor’s actual capacitance is strongly affected by its DC bias characteristics. The input capacitor is typically an X5R, X7R, or similar dielectric. Use of Y5U, Z5U, or similar dielectrics is not recommended. Input capacitor placement is critical for proper operation. Each buck’s input capacitor must be placed as close to the IC as possible. The traces from VIN_Bx to the capacitor and from the capacitor to PGNDx should as short and wide as possible. Inductor Selection The Buck converters utilize current-mode control and a proprietary internal compensation scheme to simultaneously simplify external component selection and optimize transient performance over their full operating range. The ACT88430 is optimized for opera- tion with 1.0-1.5 μH inductors. Choose an inductor with a low DC-resistance, and avoid inductor saturation by choosing inductors with DC ratings that exceed the maximum output current by at least 30%. The following equation calculates the inductor ripple current. ∆������������������������ =�1−�������������������������������������������������������������������������������������∗������������������������������������������������ ������������������������������������∗������������ Where VOUT is the output voltage, VIN is the input voltage, FSW is the switching frequency, and L is the inductor value. Output Capacitor Selection The ACT88430 is designed to use small, low ESR, ceramic output capacitors. Buck1 typically requires a 44uF output capacitor while Buck2, Buck3, and Buck4 |
|
ссылки URL |
| Вашему бизинису помогли Аллдатащит? [ DONATE ] |
Что такое Аллдатащит | реклама | контакт | Конфиденциальность | Ссылка на техническое описание | обмен ссыками | поиск по производителю 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 |