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參數(shù)資料
| 型號(hào)： | ISL6535 |
| 廠商： | Intersil Corporation |
| 英文描述： | Synchronous Buck Pulse-Width Modulator (PWM) Controller |
| 中文描述： | 同步降壓脈寬調(diào)制（PWM）控制器 |
| 文件頁(yè)數(shù)： | 7/14頁(yè) |
| 文件大?。?/td> | 397K |
| 代理商： | ISL6535 |
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7
FN9255.0
January 17, 2006
ISL6535
typical soft-start interval. The rise time of the output voltage is,
therefore, dependent upon the value of the soft start capacitor,
C
SS
. If the internal reference is used, then the soft start
capacitance value can be calculated through:
If an external reference is used, then the soft start
capacitance can be calculated through:
Prebiased Load Startup
Drivers are held in tri-state (UG pulled to Phase, LG pulled to
PGND) at the beginning of a soft-start cycle until two PWM
pulses are detected. The low side MOSFET is turned on first
to provide for charging of the bootstrap capacitor. This
method of driver activation provides support for startup into
prebiased loads by not activating the drivers until the control
loop has entered its linear region, thereby substantially
reducing output transients that would otherwise occur had
the drivers been activated at the beginning of the soft-start
cycle.
SSDONE
Soft-start done is only available in the 16 Lead QFN
packaging option of the ISL6535. When the soft-start pin
reaches 4V, an open drain signal is provided to support
sequencing requirements. SSDONE is deasserted by
disabling of the part, including pulling SS low, and by POR
and OCP events.
Oscillator
The oscillator is a triangular waveform, providing for leading
and falling edge modulation. The peak to peak of the ramp
amplitude is set at 1.9V and varies as a function of
frequency. At 50kHz the peak to peak amplitude is
approximately 1.8V while at 1.5MHz it is approximately 2.2V.
In the event the regulator operates at 100% duty cycle for 64
clock cycles an automatic boot cap refresh circuit will
activate turning on LG for approximately 1/2 of a clock cycle.
Overcurrent Protection
The OCP function is enabled with the drivers at startup. OCP
is implemented via a resistor (R
OCSET
) and a capacitor
(C
OCSET
) connecting the OCSET pin and the drain of the
high side MOSEFT. An internal 200
μ
A current source
develops a voltage across R
OCSET
which is then compared
with the voltage developed across the high side MOSFET at
turn on as measured at the PHASE pin. When the voltage
drop across the MOSFET exceeds the voltage drop across
the resistor, a sourcing OCP event occurs. C
OCSET
is
placed in parallel with R
OCSET
to smooth the voltage across
R
OCSET
in the presence of switching noise on the input bus.
A 120ns blanking period is used to reduce the current
sampling error due to leading-edge switching noise. An
additional simultaneous 120ns low pass filter is used to
further reduce measurement error due to noise.
OCP faults cause the regulator to disable (upper and lower
drives disabled, SSDONE pulled low, soft-start capacitor
discharged) itself for a fixed period of time, after which a
normal soft-start sequence is initiated. If the voltage on the
SS pin is already at 4V and an OCP is detected, a 30
μ
A
current sink is immediately applied to the SS pin. If an OCP
is detected during soft start, the 30
μ
A current sink will not be
applied until the voltage on the SS pin has reached 4V. This
current sink discharges the C
SS
capacitor in a linear fashion.
Once the voltage on the SS pin has reached approximately
0V, the normal soft start sequence is initiated. If the fault is
still present on the subsequent restart, the ISL6535 will
repeat this process in a hiccup mode. Figure 4 shows a
typical reaction to a repeated overcurrent condition that
places the regulator in a hiccup mode. If the regulator is
repeatedly tripping overcurrent, the hiccup period can be
approximated by the following formula:
The OCP trip point varies mainly due to MOSFET r
DS(ON)
variations and layout noise concerns. To avoid overcurrent
tripping in the normal operating load range, find the R
OCSET
resistor from the following equations with:
1. The maximum r
DS(ON)
at the highest junction
temperature;
2. The minimum I
OCSET
from the specification table;
C
SS
30
μ
A t
----------------------------
=
C
SS
30
μ
A t
REFEXT
----------------------------
=
FIGURE 4. TYPICAL OVERCURRENT PROTECTION
V
SSDONE
V
SS
I
LOAD
T
HICCUP
I
OCP
T
HICCUP
8V C
-----------------------
=
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| ISL6535IBZ | Synchronous Buck Pulse-Width Modulator (PWM) Controller |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ISL6535CBZ | 功能描述:IC REG CTRLR BUCK PWM VM 14-SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:275kHz 占空比:50% 電源電壓:18 V ~ 110 V 降壓:無(wú) 升壓:無(wú) 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:是 工作溫度:-40°C ~ 85°C 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:帶卷 (TR) |
| ISL6535CBZ-T | 功能描述:IC REG CTRLR BUCK PWM VM 14-SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:275kHz 占空比:50% 電源電壓:18 V ~ 110 V 降壓:無(wú) 升壓:無(wú) 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:是 工作溫度:-40°C ~ 85°C 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:帶卷 (TR) |
| ISL6535CRZ | 功能描述:IC REG CTRLR BUCK PWM VM 16QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:275kHz 占空比:50% 電源電壓:18 V ~ 110 V 降壓:無(wú) 升壓:無(wú) 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:是 工作溫度:-40°C ~ 85°C 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:帶卷 (TR) |
| ISL6535CRZ-T | 功能描述:IC REG CTRLR BUCK PWM VM 16-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:275kHz 占空比:50% 電源電壓:18 V ~ 110 V 降壓:無(wú) 升壓:無(wú) 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:是 工作溫度:-40°C ~ 85°C 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:帶卷 (TR) |
| ISL6535IBZ | 功能描述:IC REG CTRLR BUCK PWM VM 14-SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:275kHz 占空比:50% 電源電壓:18 V ~ 110 V 降壓:無(wú) 升壓:無(wú) 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:是 工作溫度:-40°C ~ 85°C 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:帶卷 (TR) |
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