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| 型号： | ISL8105BCBZ |
| 厂商： | Intersil |
| 文件页数： | 6/16页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 8-SOIC |
| 标准包装： | 980 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 330kHz |
| 占空比： | 100% |
| 电源电压： | 6.5 V ~ 14.4 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： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 管件 |
ISL8105B
circuitry to determine when the top-side MOSFET has turned
off.
N/C (DFN Only; Pin3, Pin 7)
These two pins in the DFN package are Not Connected.
Functional Description
COMP/EN
BGATE
STARTS
SWITCHING
Initialization (POR and OCP Sampling)
t0
BGATE/BSOC
V OUT
Figure 1 shows a start-up waveform of ISL8105B. The
Power-On-Reset (POR) function continually monitors the
bias voltage at the VBIAS pin. Once the rising POR
3.4ms
3.4ms
0ms TO 3.4ms
threshold is exceeded 4V (V POR nominal), the POR function
initiates the Overcurrent Protection (OCP) sample and hold
t1
t2 t3
t4
t5
operation (while COMP/EN is ~1V). When the sampling is
complete, V OUT begins the soft-start ramp.
V BIAS
FIGURE 2. BGATE/BSOC AND SOFT-START OPERATION
sample and hold uses a digital counter and DAC to save the
voltage, so the stored value does not degrade, for as long as
~4V POR
V OUT
V COMP/EN
the V BIAS is above V POR . See “Overcurrent Protection
variables. Upon the completion of sample and hold at t 3 , the
soft-start operation is initiated, and the output voltage ramps
up between t 4 and t 5 .
Soft-Start and Pre-Biased Outputs
Functionally, the soft-start internally ramps the reference on
the non-inverting terminal of the error amp from 0V to 0.6V in
a nominal 13.6ms. The output voltage will thus follow the
ramp, from zero to final value, in the same 13.6ms (the
FIGURE 1. POR AND SOFT-START OPERATION
If the COMP/EN pin is held low during power-up, the
initialization will be delayed until the COMP/EN is released
and its voltage rises above the V DISABLE trip point.
Figure 2 shows a typical power-up sequence in more detail.
The initialization starts at t 0 , when either V BIAS rises above
V POR , or the COMP/EN pin is released (after POR). The
COMP/EN will be pulled up by an internal 20μA current
source, but the timing will not begin until the COMP/EN
exceeds the V DISABLE trip point (at t 1 ). The external
capacitance of the disabling device, as well as the
compensation capacitors, will determine how quickly the
20μA current source will charge the COMP/EN pin. With
typical values, it should add a small delay compared to the
soft-start times. The COMP/EN will continue to ramp to ~1V.
From t 1 , there is a nominal 6.8ms delay, which allows the
VBIAS pin to exceed 6.5V (if rising up towards 12V), so that
the internal bias regulator can turn on cleanly. At the same
time, the BGATE/BSOC pin is initialized by disabling the
BGATE driver and drawing BSOC (nominal 21.5μA) through
R BSOC . This sets up a voltage that will represent the BSOC
trip point. At t 2 , there is a variable time period for the OCP
sample and hold operation (0ms to 3.4ms nominal; the
longer time occurs with the higher overcurrent setting). The
6
actual ramp seen on the V OUT will be less than the nominal
time), due to some initialization timing, between t 3 and t 4 ).
The ramp is created digitally, so there will be 64 small
discrete steps. There is no simple way to change this ramp
rate externally.
After an initialization period (t 3 to t 4 ), the error amplifier
(COMP/EN pin) is enabled, and begins to regulate the
converter's output voltage during soft-start. The oscillator's
triangular waveform is compared to the ramping error
amplifier voltage. This generates LX pulses of increasing
width that charge the output capacitors. When the internally
generated soft-start voltage exceeds the reference voltage
(0.6V), the soft-start is complete and the output should be in
regulation at the expected voltage. This method provides a
rapid and controlled output voltage rise; there is no large
inrush current charging the output capacitors. The entire
start-up sequence from POR typically takes up to 23.8ms; up
to 10.2ms for the delay and OCP sample and 13.6ms for the
soft-start ramp.
Figure 3 shows the normal curve in yellow; initialization
begins at t 0 , and the output ramps between t 1 and t 2 . If the
output is pre-biased to a voltage less than the expected
value, as shown by the green curve, the ISL8105B will
detect that condition. Neither MOSFET will turn on until the
FN6447.2
April 15, 2010
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ISL8105BCBZ-T | 功能描述:IC REG CTRLR BUCK PWM VM 8-SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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:-40°C ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| ISL8105BCRZ | 功能描述:IC REG CTRLR BUCK PWM VM 10-DFN 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) |
| ISL8105BCRZ-T | 功能描述:IC REG CTRLR BUCK PWM VM 10-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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:-40°C ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| ISL8105BEVAL1Z | 功能描述:EVAL BOARD ISL8105B RoHS:是 类别:编程器，开发系统 >> 评估板 - DC/DC 与 AC/DC（离线）SMPS 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:1 系列:True Shutdown™ 主要目的:DC/DC，步升 输出及类型:1，非隔离 功率 - 输出:- 输出电压:- 电流 - 输出:1A 输入电压:2.5 V ~ 5.5 V 稳压器拓扑结构:升压 频率 - 开关:3MHz 板类型:完全填充 已供物品:板 已用 IC / 零件:MAX8969 |
| ISL8105BEVAL2Z | 功能描述:EVALUATION BOARD FOR ISL8105B RoHS:是 类别:编程器，开发系统 >> 评估板 - DC/DC 与 AC/DC（离线）SMPS 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:1 系列:True Shutdown™ 主要目的:DC/DC，步升 输出及类型:1，非隔离 功率 - 输出:- 输出电压:- 电流 - 输出:1A 输入电压:2.5 V ~ 5.5 V 稳压器拓扑结构:升压 频率 - 开关:3MHz 板类型:完全填充 已供物品:板 已用 IC / 零件:MAX8969 |
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