Datasheet > AS1920_07

AS1920_07

更新时间： 2022-05-10 15:58:19

品牌	Logo	应用领域
艾迈斯 - AMSCO		微处理器监控
页数	文件大小	规格书
15页	733K
描述
Triple-Voltage, Micro-Power Microprocessor Supervisory Circuits

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AS1920_07 数据手册

AS1920/AS1922

Datasheet - Application Information

9 Application Information

Supply Monitoring

The AS1920/AS1922 are low-power, high-accuracy triple-supply monitoring circuits with a single 200ms microproces-

sor reset output.

All VCC inputs (VCC18, VCC3, and VCCA) must be above their thresholds to prevent a reset from being asserted. The

AS1920/AS1922 will assert a reset during powerup, powerdown and brownout conditions on one or all of the VCC

inputs.

Power Detect

The AS1920/AS1922 is powered from the 3V input pin (VCC3). The power detect circuitry ensures that the device pulls

pin RESETN low as soon as the primary input pin is ≥1V or the secondary input pin is ≥1V.

Powerup

The power detect circuitry ensures that RESETN will be low when either VCC18 or VCC3 ≥1V. As long as any one of the

VCC inputs is below its reset threshold, RESETN will stay at a logic low. When all VCC inputs have stabilized, an inter-

nal timer will be started and RESETN will be driven high after 200ms.

Powerdown

On powerdown, if any of the VCC inputs drop below its threshold, RESETN is held at a logic low (0.3V) and is guaran-

teed until VCC3 and VCC18 < 1V.

Override Functions

As the trip points for VCC3 and VCC18 will always be greater than the trip point for VCCA, if pin VCCA is not used, it

should be tied to VCC3 or VCC18. In a similar manner if pin VCC18 is not used it should be tied to VCC3. Tying VCC3 to

VCC18 and operating from a 1.8V supply will assure the continuous assertion of RESETN.

Note: Pin VCC3 must be used in all configurations.

Ensuring RESETN Valid for Supply Voltages < 1V

When the supplies drops below 1V the RESETN output current sink capability is greatly reduced. Stray currents and

stray capacitance to signals other than GND can cause the RESETN output to float. This is not relevant for most appli-

cations since most microprocessors and other circuits do not operate with a supply voltage < 1V.

In applications where the RESETN output must be valid down to 0V, a pulldown resistor from pin RESETN to ground

will ensure RESETN is held low (see Figure 12).

Figure 12. Typical Application w/Resistor on RESETN Output to GND

VCC3

AS1920/

AS1922

1.8V

RESETN

VCC18

100kΩ

Adjustable

Supply

VCCA

GND

The value of the pulldown resistor (R3) is a trade-off between pulldown strength and loading of the RESETN pin. If the

value of R3 is too large RESETN may still float, and if the value of R3 is too small it may load RESETN and also use

excess supply current, therefore a value of 100kΩ is recommended for the pulldown resistor.

www.austriamicrosystems.com

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与AS1920_07相关器件

型号	品牌	获取价格	描述	数据表
AS1920_1	AMSCO	获取价格	Triple-Voltage, Micro-Power Microprocessor Supervisory Circuits
AS192-000	SKYWORKS	获取价格	PHEMT GaAs IC High-Power SP4T Switch 0.1-2.5 GHz
AS1920-18	AMSCO	获取价格	Triple-Voltage, Micro-Power Microprocessor Supervisory Circuits
AS1920-18-T	AMSCO	获取价格	Triple-Voltage, Micro-Power Microprocessor Supervisory Circuits
AS1922	AMSCO	获取价格	Triple-Voltage, Micro-Power Microprocessor Supervisory Circuits
AS1922-18	AMSCO	获取价格	Triple-Voltage, Micro-Power Microprocessor Supervisory Circuits
AS1922-18-T	AMSCO	获取价格	Triple-Voltage, Micro-Power Microprocessor Supervisory Circuits
AS1923	AMSCO	获取价格	Quad-Voltage Microprocessor Supervisory Circuit
AS1923_04	AMSCO	获取价格	Quad-Voltage Microprocessor Supervisory Circuit
AS192-300	ALPHA	获取价格	PHEMT GaAs IC High Power SP4T Switch 0.1-2.5 GHz

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