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| 型号： | ISL6307BCRZ-T |
| 厂商： | Intersil |
| 文件页数： | 13/33页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 48-QFN |
| 标准包装： | 4,000 |
| PWM 型： | 电压模式 |
| 输出数： | 6 |
| 频率 - 最大： | 275kHz |
| 占空比： | 66.7% |
| 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： | 0°C ~ 70°C |
| 封装/外壳： | 48-VFQFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
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ISL6307B
PWM Operation
The timing of each converter leg is set by the number of
active channels. The default channel setting for the
ISL6307B is four. One switching cycle is defined as the time
between PWM1 pulse termination signals. The pulse
termination signal is an internally generated clock signal
which triggers the falling edge of PWM1. The cycle time of
the pulse termination signal is the inverse of the switching
frequency set by the resistor between the FS pin and
ground. Each cycle begins when the clock signal commands
the channel-1 PWM output to go low. The PWM1 transition
PWM
I L
I SEN
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,
0.5Tsw
SAMPLE CURRENT, I n
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. Connecting both PWM3 and PWM4 to VCC
selects single-channel operation.
Once a PWM signal transitions low, it is held low for a
minimum of 1/3 cycle. This forced off time is required to
ensure an accurate current sample. Current sensing is
described in the next section. After the forced off time
expires, the PWM output is enabled. The PWM output state
is driven by the position of the error amplifier output signal,
V COMP , minus the current correction signal relative to the
sawtooth ramp as illustrated in Figure 7. When the modified
V COMP voltage crosses the sawtooth ramp, the PWM output
transitions high. The MOSFET driver detects the change in
state of the PWM signal and turns off the synchronous
(lower) MOSFET and turns on the upper MOSFET. The
PWM signal will remain high until the pulse termination
SWITCHING PERIOD
TIME
FIGURE 3. SAMPLE AND HOLD TIMING
Current Sensing
The ISL6307B supports inductor DCR sensing, MOSFET
R DS(ON) sensing, or resistive sensing techniques. The
internal circuitry, shown in Figures 4, 5, and 6, represents
one channel 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.
INDUCTOR DCR SENSING
An inductor ’s winding is characteristic of a distributed
resistance as measured by the DCR (Direct Current
Resistance) parameter. Consider the inductor DCR as a
separate lumped quantity, as shown in Figure 4. The
channel current I L , flowing through the inductor, will also
pass through the DCR. Equation 3 shows the s-domain
signal marks the beginning of the next cycle by triggering the
PWM signal low.
Current Sampling
equivalent voltage across the inductor V L .
V L = I L ? ( s ? L + DCR )
(EQ. 3)
During the forced off-time following a PWM transition low,
the associated channel current sense amplifier uses the
ISEN inputs to reproduce a signal proportional to the
inductor current, I L . This current gets sampled starting 1/6
period after each PWM goes low and continuously gets
A simple R-C network across the inductor extracts the DCR
voltage, as shown in Figure 4.
The voltage on the capacitor V C , can be shown to be
proportional to the channel current I L , see Equation 4.
? s ? ------------- + 1 ? ? ( DCR ? I )
( s ? RC + 1 )
sampled for 1/3 period, or until the PWM goes high,
whichever comes first. No matter the current sense method,
the sense current, I SEN , is simply a scaled version of the
inductor current. Coincident with the falling edge of the PWM
V C =
L
? DCR ? L
---------------------------------------------------------------------
(EQ. 4)
signal, the sample and hold circuitry samples the sensed
current signal I SEN , as illustrated in Figure 3.
Therefore, the sample current, I n , is proportional to the
output current and held for one switching cycle. The sample
current is used for current balance, load-line regulation, and
overcurrent protection.
13
If the R-C network components are selected such that the
RC time constant (= R*C) matches the inductor time
constant (= L/DCR), the voltage across the capacitor V C is
equal to the voltage drop across the DCR, i.e. proportional to
the channel current.
FN9225.0
March 9, 2006
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相关代理商/技术参数 |
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|---|---|
| ISL6307BIRZ | 功能描述:软开关 PWM 控制器 W/ANNEAL 6-PHS VR11 CNTRLR INDUSTRIAL RoHS:否 制造商:Fairchild Semiconductor 输出端数量: 输出电流: 开关频率: 工作电源电压:30 V 电源电流: 最大工作温度:+ 105 C 最小工作温度:- 40 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Reel |
| ISL6307BIRZ-T | 功能描述:软开关 PWM 控制器 W/ANNEAL 6-PHS VR11 CNTRLR INDUSTRIAL RoHS:否 制造商:Fairchild Semiconductor 输出端数量: 输出电流: 开关频率: 工作电源电压:30 V 电源电流: 最大工作温度:+ 105 C 最小工作温度:- 40 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Reel |
| ISL6307CRZ | 功能描述:IC REG CTRLR BUCK PWM VM 48-QFN 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) |
| ISL6307CRZ-T | 功能描述:IC REG CTRLR BUCK PWM VM 48-QFN 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) |
| ISL6307IRZ | 功能描述:IC REG CTRLR BUCK PWM VM 48-QFN 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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