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| 型号： | SI8250DK |
| 厂商： | Silicon Laboratories Inc |
| 文件页数： | 16/32页 |
| 文件大小： | 0K |
| 描述： | DEVELOPMENT KIT FOR SI8250/1/2 |
| 标准包装： | 1 |
| 主要目的： | DC/DC，步降 |
| 输出及类型： | 1，隔离 |
| 输出电压： | 1V |
| 电流 - 输出： | 35A |
| 输入电压： | 36 ~ 75 V |
| 稳压器拓扑结构： | 降压 |
| 频率 - 开关： | 400kHz |
| 板类型： | 完全填充 |
| 已供物品： | 板，线缆，CD，电源，USB 适配器 |
| 已用 IC / 零件： | SI8250，SI8251，SI8252 |
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Si8250/1/2
3.1. System Operation
isolated dc/dc converter operating in digital voltage
mode control. The output voltage signal connects to the
V SENSE input through a resistive divider, limiting the
common-mode voltage range applied to ADC1 to a
maximum of V REF . The equivalent resistance of the
divider and the capacitor form an anti-aliasing filter with
a cutoff frequency equal to ADC1 sampling frequency
divided by 2 (the amplitudes of frequencies above fS/2
must be minimized to prevent aliasing).
Differential ADC1 and the DSP Filter Engine together
perform the same function as an analog error amplifier
and associated RC compensation network. ADC1
digitizes the difference between the scaled output
voltage and a programmable reference voltage provided
by the REFDAC. The ADC1 output signal is frequency-
compensated (in the digital domain) by the DSP Filter
Engine. The resulting output from the DSP Filter Engine
is a digital code that represents the compensated duty
cycle ratio, u(n). The digital PWM generator (DPWM)
directly varies output timing to the external gate drivers
based on the value of u(n) until the difference between
V SENSE and the ADC1 reference level is driven to zero.
Sensing circuitry within the power stages (current
transformer, sense amp, etc.) provides a signal
representative of inductor or transformer current. This
signal connects to the pulse-by-pulse current-limiting
hardware in the Si8250/1/2 via the IPK input pin. This
current-limiting circuitry is similar to that found in a
voltage mode analog PWM. It contains a fast analog
comparator and a programmable leading-edge blanking
circuit to prevent unwanted tripping of the current-
sensing circuitry on the leading edge of the current
pulse. Current limiting occurs when the sensed current
exceeds the programmed threshold. When this occurs,
the ongoing active portions of the PWM outputs are
terminated. A programmable OCP counter keeps track
of the number of consecutive current limit cycles and
automatically shuts the supply down when the
accumulated number of limit cycles exceeds the
programmed maximum.
The System Management Processor is based on a 50
million instruction per second (MIPS) 8051 CPU and
dedicated A/D converter (ADC0). ADC0 digitizes key
analog parameters that are used by the MCU to provide
protection and manage and control other aspects of the
power system. Onboard digital peripherals include
timers, an SMBus interface port, and a universal
asynchronous receiver/transmitter (UART) for serial
communications (useful for communicating across an
isolation boundary).
The System Management Processor serves several
purposes:
1. Continuously optimizes Control Processor operation
(e.g. efficient optimization)
2. Executes user-specific algorithms (e.g. support for
proprietary system interfaces)
3. Provides regulation for low-bandwidth system
variables (e.g. V IN feed-forward)
4. Performs system fault detection and recovery
5. Provides system housekeeping functions, such as
SMBus communication support
6. Manages external device functions (e.g. external
supply sequencing, fan control/monitoring)
Si8250/1/2 system development requires using the
Si8250DK, a comprehensive development kit providing
all required hardware and software for control system
design. It comes complete with prewritten and verified
application software and a set of tools that enable the
user to adapt this software to the end application. It also
includes a turnkey isolated half-bridge dc/dc converter
based on the Si8250/1/2 for evaluation and
experimentation.
3.2. Control Processor Functional Block
Descriptions (Figure 1)
3.2.1. ADC 1
Differential input, 10 Msps control loop analog-to-digital
converter. ADC1 digitizes the difference between the
V SENSE input and the programmable voltage reference
level from the REFDAC. ADC1 can be operated at 1.25,
2.5, 5, or 10 Msps and has a programmable LSB size to
prevent limit cycle oscillation (Limit cycle oscillation can
also be avoided using dithering to increase DPWM
resolution). ADC1 has programmable conversion rates
of 1.25, 2.5, 5, or 10 Msps to accommodate a wide loop
gain range. ADC1 also contains a hardware transient
detector that interrupts the CPU at the onset of an
output load or unload transient. The CPU responds by
executing specific algorithms to accelerate output
recovery. These algorithms may include increasing loop
bandwidth or other measures.
3.2.2. REFDAC
9-bit digital-to-analog converter provides the output
voltage reference setting. The REFDAC uses the
onboard band gap as its voltage reference, or it can be
referenced to an external voltage reference source.
REFDAC is used for output voltage calibration,
margining, and positioning. The CPU continuously
manages the REFDAC during soft-start and soft-stop.
3.2.3. DSP Filter Engine
This two-stage loop compensation filter is the functional
equivalent of an active RC compensation in an analog
16
Rev. 1.0
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相关代理商/技术参数 |
参数描述 |
|---|---|
| SI8250-IM | 功能描述:电压监测器/监控器 SMPS Controller RoHS:否 制造商:Texas Instruments 监测电压数:2 监测电压:Adjustable 输出类型:Open Drain 欠电压阈值: 过电压阈值: 准确性:1 % 工作电源电压:1.5 V to 6.5 V 工作电源电流:1.8 uA 最大工作温度:+ 125 C 封装 / 箱体:SON-6 安装风格:SMD/SMT |
| SI8250-IMR | 制造商:Silicon Laboratories Inc 功能描述:VOLT SUPERVISOR PWR SUPPLY 0.05V TO 0.8V 28QFN - Tape and Reel 制造商:Silicon Laboratories Inc 功能描述:IC DIGITAL PWR CONTROLLER 32LQFP 制造商:Silicon Laboratories Inc 功能描述:32K 28 Pin SMPS Controller |
| SI8250-IQ | 功能描述:电压监测器/监控器 SMPS Controller RoHS:否 制造商:Texas Instruments 监测电压数:2 监测电压:Adjustable 输出类型:Open Drain 欠电压阈值: 过电压阈值: 准确性:1 % 工作电源电压:1.5 V to 6.5 V 工作电源电流:1.8 uA 最大工作温度:+ 125 C 封装 / 箱体:SON-6 安装风格:SMD/SMT |
| SI8250-IQR | 制造商:Silicon Laboratories Inc 功能描述:VOLT SUPERVISOR PWR SUPPLY 0.05V TO 0.8V 32LQFP - Tape and Reel 制造商:Silicon Laboratories Inc 功能描述:IC DIGITAL PWR CONTROLLER 32LQFP 制造商:Silicon Laboratories Inc 功能描述:32K 32 Pin SMPS Controller |
| SI8251 | 制造商:SILABS 制造商全称:SILABS 功能描述:DIGITAL POWER CONTROLLER |
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