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| 型号： | ISL8105BIRZ |
| 厂商： | Intersil |
| 文件页数： | 11/16页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 10-DFN |
| 标准包装： | 100 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 330kHz |
| 占空比： | 100% |
| 电源电压： | 6.5 V ~ 14.4 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： | -40°C ~ 85°C |
| 封装/外壳： | 10-VFDFN 裸露焊盘 |
| 包装： | 管件 |
ISL8105B
earlier. Locate the capacitor, C BOOT , as close as practical to
the BOOT and LX pins. All components used for feedback
For the purpose of this analysis, C and ESR represent the total
output capacitance and its equivalent series resistance.
F LC = ---------------------------
F CE = ---------------------------------
compensation (not shown) should be located as close to the
IC as practical.
1
2 π ? L ? C
1
2 π ? C ? ESR
(EQ. 4)
Feedback Compensation
This section highlights the design considerations for a
voltage-mode controller requiring external compensation. To
address a broad range of applications, a type-3 feedback
network is recommended (see Figure 9).
Figure 9 highlights the voltage-mode control loop for a
synchronous-rectified buck converter, applicable to the
ISL805B circuit. The output voltage (V OUT ) is regulated to
the reference voltage, V REF , level. The error amplifier output
(COMP pin voltage) is compared with the oscillator (OSC)
triangle wave to provide a pulse-width modulated wave with
an amplitude of V IN at the LX node. The PWM wave is
smoothed by the output filter (L and C). The output filter
capacitor bank’s equivalent series resistance is represented
by the series resistor ESR.
The compensation network consists of the error amplifier
(internal to the ISL8105B) and the external R 1 to R 3 , C 1 to C 3
components. The goal of the compensation network is to
provide a closed loop transfer function with high 0dB crossing
frequency (F 0 ; typically 0.1 to 0.3 of f SW ) and adequate phase
margin (better than +45°). Phase margin is the difference
between the closed loop phase at F 0dB and +180°. The
equations that follow relate the compensation network’s poles,
zeros and gain to the components (R 1 , R 2 , R 3 , C 1 , C 2 , and
C 3 ) in Figure 9. Use the following guidelines for locating the
poles and zeros of the compensation network:
1. Select a value for R 1 (1k Ω to 10k Ω , typically). Calculate
value for R 2 for desired converter bandwidth (F 0 ). If
setting the output voltage to be equal to the reference set
voltage as shown in Figure 9, the design procedure is
d MAX ? V IN ? F LC
COMP
R 2
E/A
C 2
-
+
C 1
FB
R 3
R 1
C 3
shown in Equation 5.
V OSC ? R 1 ? F 0
R 2 = --------------------------------------------- (EQ. 5)
2. Calculate C 1 such that F Z1 is placed at a fraction of the F LC ,
at 0.1 to 0.75 of F LC (to adjust, change the 0.5 factor to
desired number). The higher the quality factor of the output
filter and/or the higher the ratio F CE /F LC , the lower the F Z1
frequency (to maximize phase boost at F LC ).
C 1 = -----------------------------------------------
VREF
1
2 π ? R 2 ? 0.5 ? F LC
3. Calculate C 2 such that F P1 is placed at F CE .
(EQ. 6)
2 π ? R 2 ? C 1 ? F CE – 1
OSCILLATOR
V IN
V OUT
C 1
C 2 = --------------------------------------------------------
(EQ. 7)
PWM
CIRCUIT
V OSC
HALF-BRIDGE
DRIVE
TGATE
LX
L
DCR
C
4. Calculate R 3 such that F Z2 is placed at F LC . Calculate C 3
such that F P2 is placed below F SW (typically, 0.5 to 1.0
times F SW ). F SW represents the regulator ’s switching
frequency. Change the numerical factor to reflect desired
placement of this pole. Placement of F P2 lower in
frequency helps reduce the gain of the compensation
network at high frequency, in turn reducing the HF ripple
BGATE
ESR
component at the COMP pin and minimizing resultant
duty cycle jitter.
F SW
F LC
C 3 = -------------------------------------------------
ISL8105B EXTERNAL CIRCUIT
FIGURE 9. VOLTAGE-MODE BUCK CONVERTER
COMPENSATION DESIGN
R 1
R 3 = ----------------------
------------ – 1
1
2 π ? R 3 ? 0.7 ? F SW
(EQ. 8)
The modulator transfer function is the small-signal transfer
function of V OUT /V COMP . This function is dominated by a DC
gain, given by d MAX V IN /V OSC , and shaped by the output filter,
with a double pole break frequency at F LC and a zero at F CE .
11
It is recommended that a mathematical model is used to plot
the loop response. Check the loop gain against the error
amplifier ’s open-loop gain. Verify phase margin results and
adjust as necessary. Equations 9 and 10 describe the
frequency response of the modulator (G MOD ), feedback
compensation (G FB ) and closed-loop response (G CL ):
FN6447.2
April 15, 2010
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参数描述 |
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| ISL8105BIRZ-T | 功能描述:IC REG CTRLR BUCK PWM VM 10-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:275kHz 占空比:50% 电源电压:18 V ~ 110 V 降压:无 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:是 工作温度:-40°C ~ 85°C 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) |
| ISL8105CRZ | 功能描述:IC REG CTRLR BUCK PWM VM 10-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:275kHz 占空比:50% 电源电压:18 V ~ 110 V 降压:无 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:是 工作温度:-40°C ~ 85°C 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) |
| ISL8105CRZ-T | 功能描述:IC REG CTRLR BUCK PWM VM 10-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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:-40°C ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| ISL8105EVAL1 | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:+5V or +12V Single-Phase Synchronous Buck Converter PWM Controller with Integrated MOSFET Gate Drivers |
| ISL8105IBZ | 功能描述:IC REG CTRLR BUCK PWM VM 8-SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:275kHz 占空比:50% 电源电压:18 V ~ 110 V 降压:无 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:是 工作温度:-40°C ~ 85°C 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) |
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