参数资料
| 型号： | ISL95872HRUZ-T |
| 厂商： | Intersil |
| 文件页数： | 10/17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
The dotted red and blue lines in Figure 12 represent the time
R2
delayed behavior of V OUT and V COMP in response to a load
transient when an integrator is used. The solid red and blue lines
V OUT
R1
V COMP
illustrate the increased response of R4? in the absence of the
integrator capacitor.
Diode Emulation
V DAC
FIGURE 10. NON-INTEGRATED R4 TM ERROR-AMPLIFIER
CONFIGURATION
R4 TM LOOP GAIN (dB)
L/C DOUBLE-POLE
The polarity of the output inductor current is defined as positive
when conducting away from the phase node, and defined as
negative when conducting towards the phase node. The DC
component of the inductor current is positive, but the AC
component known as the ripple current, can be either positive or
negative. Should the sum of the AC and DC components of the
inductor current remain positive for the entire switching period,
the converter is in continuous-conduction-mode (CCM). However,
if the inductor current becomes negative or zero, the converter is
in discontinuous-conduction-mode (DCM).
p1
p2
SYSTEM HAS 2 POLES
AND 1 ZERO
Unlike the standard DC/DC buck regulator, the synchronous
rectifier can sink current from the output filter inductor during
z1
CURRENT-MODE
ZERO
NO COMPENSATOR IS
NEEDED
DCM, reducing the light-load efficiency with unnecessary
conduction loss as the low-side MOSFET sinks the inductor
current. The ISL95872 controller avoids the DCM conduction loss
by making the low-side MOSFET emulate the current-blocking
behavior of a diode. This smart-diode operation called diode-
emulation-mode (DEM) is triggered when the negative inductor
R4 TM
f (Hz)
FIGURE 11. UNCOMPENSATED R4 TM OPEN-LOOP RESPONSE
Transient Response
In addition to requiring a compensation zero, the integrator in
traditional architectures also slows system response to transient
conditions. The change in COMP voltage is slow in response to a
rapid change in output voltage. If the integrating capacitor is
removed, COMP moves as quickly as V OUT , and the modulator
immediately increases or decreases switching frequency to
recover the output voltage.
I OUT
t
R3 TM
V COMP
current produces a positive voltage drop across the r DS(ON) of the
low-side MOSFET for eight consecutive PWM cycles while the
LGATE pin is high. The converter will exit DEM on the next PWM
pulse after detecting a negative voltage across the r DS(ON) of the
low-side MOSFET.
It is characteristic of the R4? architecture for the PWM switching
frequency to decrease while in DCM, increasing efficiency by
reducing unnecessary gate-driver switching losses. The extent of
the frequency reduction is proportional to the reduction of load
current. Upon entering DEM, the PWM frequency is forced to fall
approximately 30% by forcing a similar increase of the window
voltage V W . This measure is taken to prevent oscillating between
modes at the boundary between CCM and DCM. The 30%
increase of V W is removed upon exit of DEM, forcing the PWM
switching frequency to jump back to the nominal CCM value.
Overcurrent
The overcurrent protection (OCP) setpoint is programmed with
V OUT
t
t
resistor R OCSET , which is connected across the OCSET and
PHASE pins. Resistor R O is connected between the VO pin and
the actual output voltage of the converter. During normal
operation, the VO pin is a high impedance path, therefore there is
no voltage drop across R O . The value of resistor R O should always
match the value of resistor R OCSET .
FIGURE 12. R3 TM vs R4 TM IDEALIZED TRANSIENT RESPONSE
10
FN7974.0
January 26, 2012
相关PDF资料 |
PDF描述 |
|---|---|
| ISL95874IRUZ-T | IC CTRLR PWM 1PHASE GPU 16UTQFN |
| ISL97516IUZ | IC REG BOOST ADJ 1A 8MSOP |
| ISL97519AIUZ-TK | IC REG BOOST ADJ 1A 8MSOP |
| ISL97519IUZ-T | IC REG BOOST ADJ 1A 8MSOP |
| ISL97522IRZ-TK | IC SUPPLY CTRL 4CH TFT-LCD 38QFN |
相关代理商/技术参数 |
参数描述 |
|---|---|
| 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 |
发布紧急采购，3分钟左右您将得到回复。