参数资料
| 型号： | ISL62881HRTZ |
| 厂商： | Intersil |
| 文件页数： | 18/35页 |
| 文件大小： | 0K |
| 描述： | IC REG PWM SGL PHASE 28TQFN |
| 标准包装： | 75 |
| 应用： | 控制器，Intel IMVP-6.5? |
| 输入电压： | 5 V ~ 25 V |
| 输出数： | 1 |
| 输出电压： | 0.013 V ~ 1.5 V |
| 工作温度： | -10°C ~ 100°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-WFQFN 裸露焊盘 |
| 供应商设备封装： | 28-TQFN-EP（4x4） |
| 包装： | 管件 |
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ISL62881, ISL62881B
Overshoot Reduction Function
The ISL62881 has an optional overshoot reduction function,
enabled or disabled by the resistor from the COMP pin to GND, as
shown in Table 3.
Inductor DCR Current-Sensing Network
PHASE
When a load release occurs, the energy stored in the inductors
will dump to the output capacitor, causing output voltage
overshoot. The inductor current freewheels through the low-side
RSUM
ISUM+
MOSFET during this period of time. The overshoot reduction
function turns off the low-side MOSFET during the output voltage
L
RNTCS
+
overshoot, forcing the inductor current to freewheel through the
low-side MOSFET body diode. Since the body diode voltage drop
is much higher than MOSFET R DS(ON) voltage drop, more energy
is dissipated on the low-side MOSFET therefore the output
voltage overshoot is lower.
DCR
RNTC
RP
CN VCN
-
RI
ISUM-
If the overshoot reduction function is enabled, the ISL62881
monitors the COMP pin voltage to determine the output voltage
overshoot condition. The COMP voltage will fall and hit the clamp
voltage when the output voltage overshoots. The ISL62881 will
turn off LGATE when COMP is being clamped. The low-side
MOSFET in the power stage will be turned off. When the output
voltage has reached its peak and starts to come down, the COMP
voltage starts to rise and is no longer clamped. The ISL62881 will
resume normal PWM operation.
While the overshoot reduction function reduces the output
voltage overshoot, energy is dissipated on the low-side MOSFET,
causing additional power loss. The more frequent the transient
event, the more power loss is dissipated on the low-side MOSFET.
The MOSFET may face severe thermal stress when transient
events happen at a high repetitive rate. User discretion is advised
when this function is enabled.
IO
FIGURE 13. DCR CURRENT-SENSING NETWORK
Figure 13 shows the inductor DCR current-sensing network for a
2-phase solution. An inductor current flows through the DCR and
creates a voltage drop. The inductor has a resistors in R sum
connected to the phase-node-side pad and a PCB trace
connected to the output-side pad to accurately sense the
inductor current by sensing the DCR voltage drop. The sensed
current information is fed to the NTC network (consisting of
R ntcs , R ntc and R p ) and capacitor C n . R ntc is a negative
temperature coefficient (NTC) thermistor, used to
temperature-compensate the inductor DCR change. The inductor
current information is presented to the capacitor C n . Equations 7
through 11 describe the frequency-domain relationship between
V Cn ( s ) = ? ----------------------------------------- × DCR ? × I o ( s ) × A cs ( s )
R ntcnet = ---------------------------------------------------
1 + ------
ω L
ω sns
ω L = ------------
Key Component Selection
R BIAS
The ISL62881 uses a resistor (1% or better tolerance is
recommended) from the RBIAS pin to GND to establish highly
accurate reference current sources inside the IC. Using
R BIAS = 147k Ω sets the controller for CPU core application and
using R BIAS = 47k Ω sets the controller for GPU core application.
Do not connect any other components to this pin. Do not connect
any capacitor to the RBIAS pin as it will create instability.
Care should be taken in layout that the resistor is placed very
close to the RBIAS pin and that a good quality signal ground is
connected to the opposite side of the R BIAS resistor.
R is and C is
inductor total current I o (s) and C n voltage V Cn (s):
? R ntcnet ?
? R ntcnet + R sum ?
( R ntcs + R ntc ) × R p
R ntcs + R ntc + R p
s
s
A cs ( s ) = ----------------------
1 + ------------
DCR
L
(EQ. 7)
(EQ. 8)
(EQ. 9)
(EQ. 10)
ω sns = ------------------------------------------------------
----------------------------------------- × C n
As Figures 1 and 2 show, the ISL62881 needs the
R is - C is network across the ISUM+ and the ISUM- pins to stabilize
the droop amplifier. The preferred values are R is = 82.5 Ω and
C is = 0.01μF. Slight deviations from the recommended values are
acceptable. Large deviations may result in instability.
18
1 (EQ. 11)
R ntcnet × R sum
R ntcnet + R sum
Transfer function A cs (s) always has unity gain at DC. The inductor
DCR value increases as the winding temperature increases,
giving higher reading of the inductor DC current. The NTC R ntc
values decreases as its temperature decreases. Proper
selections of R sum , R ntcs , R p and R ntc parameters ensure that
V Cn represents the inductor total DC current over the
temperature range of interest.
FN6924.3
June 16, 2011
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相关代理商/技术参数 |
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|---|---|
| ISL62881HRTZ-T | 功能描述:直流/直流开关调节器 1 PHS PWM BUCKG FOR MICROPROCESR PWR SUP RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| ISL62882 | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:Multiphase PWM Regulator for IMVP-6.5 Mobile CPUs and GPUs |
| ISL62882B | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:Multiphase PWM Regulator for IMVP-6.5 Mobile CPUs and GPUs |
| ISL62882BHRTZ | 功能描述:直流/直流开关调节器 2 PHS PWM BUCKG FOR MICROPROC PWR SUP RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| ISL62882BHRTZR5411 | 制造商:Intersil Corporation 功能描述: |
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