STM1812 Low Power Reset Circuit

STM181x devices are low power reset devices used to monitor power supplies for microcontrollers. They perform a single function: asserting a reset signal whenever VCCsupply voltage drops below a preset value and keeping it asserted until VCChas risen above the preset threshold for a minimum period of time (trec). They provide excellent circuit reliability without additional external components when used with +3.0 V / +3.3 V (STM1815–STM1818), and +5 V (STM1810–STM1813) power supply systems.

A precision voltage reference and comparator monitors the VCCinput for an out-of-tolerance condition. When an invalid VCCcondition occurs, the reset output (RST) is forced low (or high in the case of RST) and remains asserted for trecafter VCCrises above the reset threshold. The STM1813/1818 also keep reset asserted for trecafter the output is momentarily pulled to ground by an external push-button switch.

The STM1812 and STM1817 have an active-high, push-pull output. The STM1810 and STM1815 (push-pull) and STM1811, STM1813, STM1816, and STM1818 (open-drain) have an active-low RSToutput. The open-drain devices (STM1811 / STM1813 / STM1816 / STM1818) also have an internal pull-up resistor to VCC. The STM1813 and STM1818 feature a debounced manual reset feature that asserts a reset if the RSTpin is pulled low for more than 1.5 μs. When used to initiate manual reset, RSTdebounces signals from devices such as mechanical switches. For devices with this feature, the release of the external switch triggers the reset period.

The STM181x devices are guaranteed to output the correct logic state for VCCdown to 1.0 V (0 °C to +105 °C). They also provide a reset comparator designed to ignore fast transients on VCC.

Reset thresholds are available between +2.55 V and +4.62 V. These small, low power devices are ideal for use in portable equipment. All are available in the space-saving 3-pin SOT23 package, and are specified from –40 °C to +105 °C

技术特性

Precision monitoring of 3 V, 3.3 V, and 5 V supply voltages
Four output configurations:
- Push-pull, active-high (STM1812,1817)
- Push-pull, active-low (STM1810,1815)
- Open-drain, active-low (STM1811,1816)
- Open-drain, active-low with push-button detect (STM1813,1818)
Reset pulse width - 100 ms (min.)
Low supply current - 4 μA (typ.)
Guaranteed assertion down to VCC= 1.0 V (0 °C to 105 °C)
Factory-trimmed reset thresholds of 2.55 V, 2.88 V, 3.06 V, 4.37 V, and 4.62 V (typ.)
Power supply transient immunity
Push-button/manual reset detect (STM1813/1818)
Operating temperature: –40 °C to 105 °C
± 2.5% reset threshold accuracy:(–40 °C to 105 °C)
Available in the SOT23-3 package
Fully compatible with DS181x and MXD181x products

功能框图

STM1812 订购信息

订购型号	产品状态	美金价格	数量	封装	包装形式	温度范围	材料声明
STM1812LWX7F	Active	4.37	1000	SOT23	Tape And Reel	–40 °C to 105 °C	STM1812LWX7F
STM1812MWX7F	Active	4.62	1000	SOT23	Tape And Reel	–40 °C to 105 °C	STM1812MWX7F

DATASHEET

描述	版本	大小
STM1812 : Low power reset circuit	8	320KB

APPLICATION NOTES

描述	版本	大小
AN1772: How to control power-up/reset and monitor the voltage in microprocessor systems using ST reset circuits	1	105KB
AN1790: How to connect ST reset circuits to a microprocessor	1	121KB