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参数资料
| 型号： | ADMCF328BR |
| 厂商： | ANALOG DEVICES INC |
| 元件分类： | 数字信号处理 |
| 英文描述： | 0-BIT, 10 MHz, OTHER DSP, PDSO28 |
| 封装： | SOIC-28 |
| 文件页数： | 11/36页 |
| 文件大小： | 993K |
| 代理商： | ADMCF328BR |
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ADMCF328
–19–
REV. A
ADC Reference Ramp Calibration
The peak of the ADC ramp voltage should be as close as possible
to 3.5 V to achieve the optimum ADC resolution and signal range.
When the current source is in the Default State, the peak of the
ADC ramp slope will be lower than this “3.5 V” target ramp.
When the current source value is increased, the ADC ramp
slope will become closer to the target value. The “tuned” ramp
slope is the one closest to the target ramp.
A simple calibration procedure using the internal 2.5 V reference
voltage allows the selection of the ICONST_TRIM register
value to reach this:
1. A high quality linear ADC capacitor is selected using Figure
14 for a tuned ICONST.
2. Program PWMSYNCWT to proper count as in Figure 13.
3. The ADC Max Count is calculated, as described in a previ-
ous section.
4. The target reference conversion is calculated as TARGET =
(Max Count)
× (2.5 V/3.5 V).
5. Reset or software sets the ICONST_TRIM register to zero.
6. Select calibration channel in software on ADC multiplexer.
7. The calibration channel value is compared with the target
reference conversion.
8. If this value is greater than the TARGET, the ICONST_TRIM
value is incremented by one, and Step 7 is repeated.
9. If the calibration channel value is less than the TARGET,
the calibration is completed.
VREF
3.5V
0.3V
MINIMUM
RAMP
TARGET
RAMP
Figure 15. Current Ramp
Current Sense Amplier
The ADMCF328 analog circuit block also integrates an inverting
amplier, a sample-and-hold amplier, and an over-current-
trip comparator. The current sense amplier input signal range
is matched to the requirements of medium to low power motor
control applications. There is an output offset that matches the
amplier output signal range to the input signal range of the A/D
converter. This amplier is followed by a sample-and-hold
amplier that samples the current sense signal on the falling edge
of the PWMSYNC pulse. This sampling amplier system can be
used to capture the winding current signal in a brushless dc motor.
CL
BL
AL
CH
BH
AH
IWINDING
0V
CURRENT SENSE SIGNAL
CIRCUIT COMMON
+V
–V
IWINDING
IBUS
Figure 16. Typical Power Inverter Switching Topology
for DC Brushless Motor Control
Current Sense Amplier Application
The ADMCF328 current sense amplier system has been
provided to simplify the measurement of the motor winding
currents in brushless dc motor control systems. The assumed
power circuit conguration, illustrated in Figure 16, is one in
which a current sense resistor is placed between the circuit com-
mon and the return path to the negative power bus. The normal
PWM modulation scheme keeps one upper device fully conducting
while the duty cycle of one of the lower power switches is varied.
In this case, there is a negative going voltage across the resistive
shunt when the complementary upper diode conducts. The shunt
signal, IBUS, shown in Figure 17, is sampled at the midpoint of
the lower device-on period using the PWMSYNC pulse. The cap-
tured value represents the current in the motor winding IWINDING.
ADC Registers
The conguration of all registers of the ADC System is shown at
the end of the data sheet.
AUXILIARY PWM TIMERS
Overview
The ADMCF328 provides two variable frequency, variable duty
cycle, 8-bit, auxiliary PWM outputs that are available at the AUX1
and AUX0 pins when enabled. These auxiliary PWM outputs
can be used to provide switching signals to other circuits in a
typical motor control system such as power factor corrected
front-end converters or other switching power converters. Alter-
natively, by addition of a suitable lter network, the auxiliary
PWM output signals can be used as simple single-bit digital-to-
analog converters.
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相关代理商/技术参数 |
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| ADMCF328BR-REEL | 制造商:Rochester Electronics LLC 功能描述: 制造商:Analog Devices 功能描述: |
| ADMCF328-EVALKIT | 制造商:未知厂家 制造商全称:未知厂家 功能描述:28-Lead Flash Memory DSP Motor Controller with Current Sense(993.76 k) |
| ADMCF328PB | 制造商:AD 功能描述:328 ANALOG DEVICE S6H1X |
| ADMCF328-PB | 制造商:Analog Devices 功能描述:STAND ALONE PROCESSOR BOARD |
| ADMCF340 | 制造商:AD 制造商全称:Analog Devices 功能描述:DashDSPTM 64-Lead Flash Mixed-Signal DSP with Enhanced Analog Front End |
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