Os motores de busca de Datasheet de Componentes eletrônicos |
|
ACT8870QJ-T Folha de dados(PDF) 26 Page - Active-Semi, Inc |
|
ACT8870QJ-T Folha de dados(HTML) 26 Page - Active-Semi, Inc |
26 / 43 page ACT8870QJ-T Rev 3.0, 02-Oct-2017 Innovative PowerTM www.active-semi.com ActiveSwitcherTM is a trademark of Active-Semi. Copyright © 2016-2017 Active-Semi, Inc. I2CTM is a trademark of NXP 26 PWM converters that achieve peak efficiencies of up to 96.5%. The buck converters switch at 2.25MHz and are internally compensated, requiring only three small external components (Cin, Cout, and L) for operation. They ship with default output voltages that can be modified via the I2C interface for systems that require advanced power management functions. Each buck converter has a dedicated input pin and power ground pin. Each buck converter should have a dedicated input capacitor that is optimally placed to minimize the power routing loops for each buck converter. Note that even though each buck converter has separate inputs, all buck converter inputs must be connected to the same voltage potential. Buck 1 is configurable as a bypass switch for systems with a 3.3V bus voltage. The bypass switch provides full sequencing capability by allowing the 3.3V bus to be used as the input to the other supplies and still be properly sequenced to the downstream load. Tie MODE to AGND to configure Buck1 for a switching power supply. Tie MODE to VIN to configure Buck1 as a bypass switch. MODE is only sampled when VIN reaches its UVLO threshold. Changing the MODE pin after startup has no effect. When Buck1 is configured as a power supply, EXT_EN is a direct output of the ACT8870 Buck1 enable signal. When Buck1 is configured as a bypass switch, EXT_EN is a direct output of the bypass switch enable signal. The ACT8870 buck regulators are highly configurable and can be quickly and easily reconfigured via I2C. This allows them to support changes in hardware requirements without the need for PCB changes. Examples of I2C functionality are given below: Real-time power good, OV, and current limit status Ability to mask individual faults Dynamically change output voltage On/Off control Softstart ramp Slew rate control Switching delay and phase control Low power mode Overcurrent thresholds Refer to the Active-Semi Application Note describing the Register Map for full details on I2C functionality and programming ranges. Operating Mode The buck converters operate in fixed-frequency PWM mode at medium to heavy loads. They transition to a proprietary power-saving low power mode (LPM) at light loads in order to save power. Each buck converter’s LPM can be independently enabled or disabled via its DISLPM I2C bit. Setting DISLPM = 0 enables LPM while setting DISLPM = 1 disables LPM. Operating in LPM saves power, while operating in forced PWM mode gives better transient response. Each buck converter output can be programmed between 2.8V and 5.5V with the I2C register Bx_VSEL0[7:0]. Enable / Disable Control When power is applied to the IC, all converters automat- ically turn on according to a pre-programmed sequence. Once in normal operation (ACTIVE state), each con- verter can be independently disabled via I2C. Each CMI version requires a different set of command to disable a converter, so contact the factory for specific instructions if needed. Each converter contains an optional inte- grated discharge resistor that actively discharges the output capacitor when the regulator is disabled. The dis- charge function is enabled via the I2C bit Bx_DisPull- down. Soft-Start Each buck regulator contains a softstart circuit that lim- its the rate of change of the output voltage, minimizing input inrush current and ensuring that the outputs power up monotonically. This circuitry is effective any time the regulator is enabled, as well as after responding to a short circuit or other fault condition. Each regulator’s softstart time is adjustable between 300us and 1000us via its I2C bits SS_RAMP. 100% Duty Cycle Operation The buck regulators are capable of operating at up to 100% duty cycle. During 100% duty cycle operation, the high-side power MOSFETs are held on continuously, providing a direct connection from the input to the output (through the inductor), ensuring the lowest possible dropout voltage in battery powered applications. Dynamic Voltage Scaling Each buck converter supports Dynamic Voltage Scaling (DVS). DVS allows the user to optimize the processor’s energy to complete tasks by lowering the processor’s operating frequency and input voltage when lower per- formance is acceptable. In normal operation, each out- put regulates to the voltage programmed in the I2C reg- ister Bx_VSET0. During DVS, each output regulates to Bx_VSET1. The output transitions from Bx_VSET0 to Bx_VSET1 at a rate determined by the output capaci- tance and the load current. The outputs transition be- tween VSET1 and VSET0 by the rate determined by the I2C bits SLEW. |
Nº de peça semelhante - ACT8870QJ-T |
|
Descrição semelhante - ACT8870QJ-T |
|
|
Ligação URL |
Privacy Policy |
ALLDATASHEETPT.COM |
ALLDATASHEET é útil para você? [ DONATE ] |
Sobre Alldatasheet | Publicidade | Contato conosco | Privacy Policy | roca de Link | 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 |