参数资料
| 型号： | ISL95872HRUZ-T |
| 厂商： | Intersil |
| 文件页数： | 9/17页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM 16UTQFN |
| 标准包装： | 3,000 |
| PWM 型： | R4 |
| 输出数： | 1 |
| 频率 - 最大： | 300kHz |
| 电源电压： | 4.75 V ~ 5.25 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -10°C ~ 100°C |
| 封装/外壳： | 16-UFQFN |
| 包装： | 带卷 (TR) |
ISL95872
V OUT
R FB
FB
?
V COMP
COMPENSATION TO COUNTER
INTEGRATOR POLE
INTEGRATOR
FOR HIGH DC GAIN
EA
+
+
V SET
?
V REF
V OUT
V DAC
V COMP
FIGURE 8. INTEGRATOR ERROR-AMPLIFIER CONFIGURATION
SREF
R3 TM LOOP GAIN (dB)
INTEGRATOR POLE
FIGURE 7. ISL95872 VOLTAGE PROGRAMMING CIRCUIT
p1
L/C DOUBLE-POLE
R4 TM Modulator
The R4? modulator is an evolutionary step in R3? technology.
Like R3?, the R4? modulator allows variable frequency in
response to load transients and maintains the benefits of
current-mode hysteretic controllers. However, in addition, the
p2
CURRENT-MODE
ZERO z1
p3
-20dB CROSSOVER
REQUIRED FOR STABILITY
COMPENSATOR TO
ADD z2 IS NEEDED
R4? modulator reduces regulator output impedance and uses
accurate referencing to eliminate the need for a high-gain
voltage amplifier in the compensation loop. The result is a
topology that can be tuned to voltage-mode hysteretic transient
speed while maintaining a linear control model and removes the
need for any compensation. This greatly simplifies the regulator
design for customers and reduces external component cost.
Stability
The removal of compensation derives from the R4? modulator’s
lack of need for high DC gain. In traditional architectures, high DC
gain is achieved with an integrator in the voltage loop. The
integrator introduces a pole in the open-loop transfer function at
low frequencies. That, combined with the double-pole from the
output L/C filter, creates a three pole system that must be
compensated to maintain stability.
Classic control theory requires a single-pole transition through
unity gain to ensure a stable system. Current-mode architectures
(includes peak, peak-valley, current-mode hysteretic, R3? and
R4?) generate a zero at or near the L/C resonant point,
effectively canceling one of the system’s poles. The system still
contains two poles, one of which must be canceled with a zero
before unity gain crossover to achieve stability. Compensation
components are added to introduce the necessary zero.
9
f (Hz)
FIGURE 9. UNCOMPENSATED INTEGRATOR OPEN-LOOP RESPONSE
Figure 8 illustrates the classic integrator configuration for a
voltage loop error-amplifier. While the integrator provides the
high DC gain required for accurate regulation in traditional
technologies, it also introduces a low-frequency pole into the
control loop. Figure 9 shows the open-loop response that results
from the addition of an integrating capacitor in the voltage loop.
The compensation components found in Figure 8 are necessary
to achieve stability.
Because R4? does not require a high-gain voltage loop, the
integrator can be removed, reducing the number of inherent
poles in the loop to two. The current-mode zero continues to
cancel one of the poles, ensuring a single-pole crossover for a
wide range of output filter choices. The result is a stable system
with no need for compensation components or complex
equations to properly tune the stability.
Figure 10 shows the R4? error-amplifier that does not require an
integrator for high DC gain to achieve accurate regulation. The
result to the open loop response can be seen in Figure 11.
FN7974.0
January 26, 2012
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|---|---|
| ISL95873HRUZ-T | 功能描述:电流型 PWM 控制器 2-Bit PWM GPU Controller for Toshiba. Spin of ISL95872; 2.6 RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| ISL95874HRUZ-T | 功能描述:电流型 PWM 控制器 0/2 BIT PWM GPU CONTLR FOR NOTEBOOK RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| ISL95874IRUZ-T | 功能描述:电流型 PWM 控制器 0/2 BIT PWM GPU CONTLR FOR NOTEBOOK RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| ISL95875HRUZ-T | 功能描述:电流型 PWM 控制器 RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| ISL95875IRUZ-T | 功能描述:电流型 PWM 控制器 RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
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