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參數(shù)資料
| 型號： | ISL9000 |
| 廠商： | Intersil Corporation |
| 英文描述： | Dual LDO with Low Noise, Very High PSRR, and Low IQ |
| 中文描述： | 雙路LDO穩(wěn)壓器與低噪聲，高PSRR，低智商 |
| 文件頁數(shù)： | 10/11頁 |
| 文件大?。?/td> | 302K |
| 代理商： | ISL9000 |
10
FN9217.0
September 21, 2005
If EN1 is brought high, and EN2 goes high before the VO1
output stablizes, the ISL9000 delays the VO2 turn-on until
the VO1 output reaches its target level. This minimizes input
current surge due to concurrent turn-on.
If EN2 is brought high, and EN1 goes high before the VO2
output stablizes, the ISL9000 delays the VO1 turn-on until
the VO2 output reaches its target level.
If both EN1 and EN2 are brought high at the same time, the
VO1 output has priority, and is always powered up first.
During operation, whenever the VIN voltage drops below
about 1.8V, the ISL9000 immediately disables both LDO
outputs. When VIN rises back above 2.1V, the device re-
initiates its start-up sequence and LDO operation will
resume automatically.
Reference Generation
The reference generation circuitry includes a trimmed
bandgap, a trimmed voltage reference divider, a trimmed
current reference generator, and an RC noise filter. The filter
includes the external capacitor connected to the CBYP pin.
A 0.01
μ
F capacitor connected CBYP implements a 100Hz
lowpass filter, and is recommended for most high
performance applications. For the lowest noise application, a
0.1
μ
F or greater CBYP capacitor should be used. This filters
the reference noise to below the 10Hz – 1kHz frequency
band, which is crucial in many noise-sensitive applications.
The bandgap generates a zero temperature coefficient (TC)
voltage for the reference divider. The reference divider
provides the regulation reference, POR detection thresholds,
and other voltage references required for current generation
and over-temperature detection.
The current generator provides the references required for
adaptive biasing as well as references for LDO output
current limit and thermal shutdown determination.
LDO Regulation and Programmable Output Divider
The LDO Regulator is implemented with a high-gain
operational amplifier driving a PMOS pass transistor. The
design of the ISL9000 provides a regulator that has low
quiescent current, fast transient response, and overall
stability across all operating and load current conditions.
LDO stability is guaranteed for a 1
μ
F to 10
μ
F output
capacitor that has a tolerance better than 20% and ESR less
than 200m
. The design is performance-optimized for a 1
μ
F
capacitor. Unless limited by the application, use of an output
capacitor value above 4.7
μ
F is not normally needed as LDO
performance improvement is minimal.
Each LDO uses an independently trimmed 1V reference. An
internal resistor divider drops the LDO output voltage down
to 1V. This is compared to the 1V reference for regulation.
The resistor division ratio is programmed in the factory to
one of the following output voltages: 1.5V, 1.8V, 1.85, 2.5V,
2.6, 2.7, 2.8V, 2.85V, 2.9, 3.0, and 3.3V.
Power On Reset Generation
Each LDO has a separate Power-on Reset signal generation
circuit which outputs to the respective POR pins. The POR
signal is generated as follows:
A POR comparator continuously monitors the output of each
LDO. The LDO enters a power-good state when the output
voltage is above 94% of the expected output voltage for a
period exceeding the LDO PGOOD entry delay time (see
below). In the power-good state, the open-drain PORx
output is in a high-impedance state. An internal 100k
pull-
up resistor pulls the pin up to the respective LDO output
voltage. An external resistor can be added between the
PORx output and the LDO output for a faster rise time,
however, the PORx output should not connect through an
external resistor to a supply greater than the associated
LDO voltage.
The power-good state is exited when the LDO output falls
below 90% of the expected output voltage for a period longer
than the PGOOD exit delay time. While power-good is false,
the ISL9000 pulls the respective POR pin low.
For LDO-1, the PGOOD entry delay time is fixed at about
2ms while the PGOOD exit delay is about 25
μ
s. For LDO-2,
the PGOOD entry and exit delays are determined by the
value of the external capacitor connected to the CPOR pin.
For a 0.01
μ
F capacitor, the entry and exit delays are 200ms
and 25
μ
s respectively. Larger or smaller capacitor values will
yield proportionately longer or shorter delay times. The POR
exit delay should never be allowed to be less than 10
μ
s to
ensure sufficient immunity against transient induced false
POR triggering.
Overheat Detection
The bandgap provides a proportional-to-temperature current
that is indicative of the temperature of the silicon. This
current is compared with references to determine if the
device is in danger of damage due to overheating. When the
die temperature reaches about 145°C, one or both of the
LDO’s momentarily shut down until the die cools sufficiently.
In the overheat condition, only the LDO sourcing more than
50mA will be shut off. This does not affect the operation of
the other LDO. If both LDOs source more than 50mA and an
overheat condition occurs, both LDO outputs are disabled.
Once the die temperature falls back below about 110°C, the
disabled LDO(s) are re-enabled and soft-start automatically
takes place.
The ISL9000 provides short-circuit protection by limiting the
output current to about 475mA. If short circuited, an output
current of 475mA will cause die heating. If the short circuit
lasts long enough, the overheat detection circuit will turn off
the output.
ISL9000
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| ISL9000_06 | 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:Dual LDO with Low Noise, Very High PSRR, and Low IQ |
| ISL9000A | 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:Dual LDO with Low Noise, Very High PSRR and Low IQ |
| ISL9000AIRBBZ | 功能描述:IC REG LDO 1.5V .3A 10-DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 線性 系列:- 標準包裝:1 系列:- 穩(wěn)壓器拓撲結構:正，可調式 輸出電壓:1.25 V ~ 10 V 輸入電壓:2.9 V ~ 12 V 電壓 - 壓降（標準）:- 穩(wěn)壓器數(shù)量:1 電流 - 輸出:700mA 電流 - 限制（最?。?- 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:10-VFDFN 裸露焊盤 供應商設備封裝:10-DFN（3x3） 包裝:Digi-Reel® 其它名稱:NCV8535MNADJR2GOSDKR |
| ISL9000AIRBBZ-T | 功能描述:IC REG LDO 1.5V .3A 10-DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 線性 系列:- 標準包裝:1 系列:- 穩(wěn)壓器拓撲結構:正，可調式 輸出電壓:1.25 V ~ 10 V 輸入電壓:2.9 V ~ 12 V 電壓 - 壓降（標準）:- 穩(wěn)壓器數(shù)量:1 電流 - 輸出:700mA 電流 - 限制（最?。?- 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:10-VFDFN 裸露焊盤 供應商設備封裝:10-DFN（3x3） 包裝:Digi-Reel® 其它名稱:NCV8535MNADJR2GOSDKR |
| ISL9000AIRBCZ | 功能描述:IC REG LDO 1.5V/1.8V .3A 10-DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 線性 系列:- 標準包裝:1 系列:- 穩(wěn)壓器拓撲結構:正，可調式 輸出電壓:1.25 V ~ 10 V 輸入電壓:2.9 V ~ 12 V 電壓 - 壓降（標準）:- 穩(wěn)壓器數(shù)量:1 電流 - 輸出:700mA 電流 - 限制（最?。?- 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:10-VFDFN 裸露焊盤 供應商設備封裝:10-DFN（3x3） 包裝:Digi-Reel® 其它名稱:NCV8535MNADJR2GOSDKR |
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