参数资料
| 型号： | ISL6561CR-T |
| 厂商： | Intersil |
| 文件页数： | 12/26页 |
| 文件大小： | 0K |
| 描述： | IC CTRLR PWM MULTIPHASE 40-QFN |
| 标准包装： | 4,000 |
| 应用： | 控制器，Intel VR10X |
| 输入电压： | 3 V ~ 12 V |
| 输出数： | 4 |
| 输出电压： | 0.84 V ~ 1.6 V |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 40-VFQFN 裸露焊盘 |
| 供应商设备封装： | 40-QFN（6x6） |
| 包装： | 带卷 (TR) |
ISL6561
current. Reducing the inductor ripple current allows the
designer to use fewer or less costly output capacitors.
expires, the PWM output is enabled. The PWM output state
is driven by the position of the error amplifier output signal,
( V IN – N V OUT ) V OUT
L f S V
I L , PP = ------------------------------------------------------------
IN
(EQ. 2)
V COMP , minus the current correction signal relative to the
sawtooth ramp as illustrated in Figure 4. When the modified
V COMP voltage crosses the sawtooth ramp, the PWM output
Another benefit of interleaving is to reduce input ripple
current. Input capacitance is determined in part by the
maximum input ripple current. Multi-phase topologies can
improve overall system cost and size by lowering input ripple
current and allowing the designer to reduce the cost of input
capacitance. The example in Figure 2 illustrates input
currents from a three-phase converter combining to reduce
the total input ripple current.
The converter depicted in Figure 2 delivers 36A to a 1.5V
load from a 12V input. The RMS input capacitor current is
5.9A. Compare this to a single-phase converter also
stepping down 12V to 1.5V at 36A. The single-phase
converter has 11.9A RMS input capacitor current. The
single-phase converter must use an input capacitor bank
with twice the RMS current capacity as the equivalent three-
phase converter.
Figures 16, 17 and 18 in the section entitled Input Capacitor
transitions high. The MOSFET driver detects the change in
state of the PWM signal, turns off the synchronous MOSFET
and turns on the upper MOSFET. The PWM signal remains
high until the pulse termination signal commands the
beginning of the next cycle by triggering the PWM signal low.
Current Sensing
The ISL6561 supports inductor DCR sensing or MOSFET
r DS(ON) sensing. The internal circuitry, shown in Figures 3
and 5, represents channel n of an N-channel converter. This
circuitry is repeated for each channel in the converter, but
may not be active depending on the status of the PWM3 and
PWM4 pins, as described in the PWM Operation section.
MOSFET r DS(ON) Sensing
The controller can sense the channel load current by
sampling the voltage across the lower MOSFET r DS(ON) as
in Figure 6. The amplifier is ground-reference by connecting
R ISEN
Selection can be used to determine the input-capacitor RMS
current based on load current, duty cycle, and the number of
channels. They are provided as aids in determining the
optimal input capacitor solution. Figure 19 shows the single
I n
I
r DS ( ON )
SEN = I L --------------------------
V IN
phase input-capacitor RMS current for comparison.
PWM Operation
SAMPLE
&
HOLD
ISEN+(n)
I L
The timing of each converter leg is set by the number of
active channels. The default channel setting for the ISL6561
is four. One switching cycle is defined as the time between
-
R ISEN
(PTC)
ISEN-(n)
-
I L r DS ( ON )
+
PWM1 pulse termination signals. The pulse termination
signal is the internally generated clock signal that triggers
the falling edge of PWM1. The cycle time of the pulse
+
N-CHANNEL
MOSFETs
termination signal is the inverse of the switching frequency
set by the resistor between the FS pin and ground. Each
ISL6561 INTERNAL CIRCUIT
EXTERNAL CIRCUIT
cycle begins when the clock signal commands the channel-1
PWM output to go low. The PWM1 transition signals the
channel-1 MOSFET driver to turn off the channel-1 upper
MOSFET and turn on the channel-1 synchronous MOSFET.
In the default channel configuration, the PWM2 pulse
terminates 1/4 of a cycle after PWM1. The PWM3 output
follows another 1/4 of a cycle after PWM2. PWM4 terminates
another 1/4 of a cycle after PWM3.
If PWM3 is connected to VCC, two channel operation is
selected and the PWM2 pulse terminates 1/2 of a cycle later.
Connecting PWM4 to VCC selects three channel operation
and the pulse-termination times are spaced in 1/3 cycle
increments.
FIGURE 3. MOSFET r DS(ON) CURRENT-SENSING CIRCUIT
the ISEN- input to the source of the lower MOSFET. ISEN+
connects to the PHASE node through a resistor R ISEN . The
voltage across R ISEN is equivalent to the voltage drop
across the r DS(ON) of the lower MOSFET while it is
conducting. The resulting current into the ISEN+ pin is
proportional to the channel current I L . The ISEN current is
then sampled and held after sufficient settling time as
described in current sampling section. The sampled current
I n , is used for channel-current balance, load-line regulation,
and overcurrent protection. From Figure 4, the following
equation for I SEN is derived
I SEN = I L ---------------------- )
Once a PWM signal transitions low, it is held low for a
minimum of 1/3 cycle. This forced off time is required to
r DS ( ON
R ISEN
(EQ. 3)
ensure an accurate current sample. Current sensing is
described in the next section. After the forced off time
12
where I L is the channel current.
FN9098.5
May 12, 2005
相关PDF资料 |
PDF描述 |
|---|---|
| ISL6563IR-T | IC CTRLR PWM MULTIPHASE 24-QFN |
| ISL6564AIRZ | IC REG CTRLR BUCK PWM VM 40-QFN |
| ISL6564IR-T | IC REG CTRLR BUCK PWM VM 40-QFN |
| ISL6565BCV-T | IC REG CTRLR BUCK PWM VM 28TSSOP |
| ISL6566AIRZ | IC CTRLR PWM 3PHASE BUCK 40-QFN |
相关代理商/技术参数 |
参数描述 |
|---|---|
| ISL6561CRZ | 功能描述:IC CTRLR PWM MULTIPHASE 40-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
| ISL6561CRZ | 制造商:Intersil Corporation 功能描述:Pulse Width Modulation (PWM) Controller |
| ISL6561CRZA | 功能描述:IC CTRLR PWM MULTIPHASE 40-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
| ISL6561CRZA-T | 功能描述:IC CTRLR PWM MULTIPHASE 40-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
| ISL6561CRZR5208 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Intersil Corporation 功能描述: |
发布紧急采购，3分钟左右您将得到回复。