DS1238 微管理器芯片

概述

The DS1238 MicroManagers are functionally similar to the DS1236 but with pin-compatibility with the MAX691, MAX693, and MAX695 series. Additionally, the DS1238 allows for external timing control. These highly integrated monitors perform the following functions critical to microprocessor-controlled systems:

A precision temperature-compensated reference and comparator continuously monitor the system power supply. If Vcc levels breach threshold tolerance, an internal power-fail signal is generated which activates reset. When power returns to tolerance, the DS1238 holds reset for a minimum of 50ms (typically 100ms) while the power supply and processor stabilize. Optional threshold levels are available: the DS1238-5 and DS1238A-5 for resets at ±5% of a 5V supply; and the DS1238-10 and DS1238A-10 for ±10% of a 5V supply.
The watchdog timer circuitry monitors software execution. If a strobe input is not driven low prior to user-set timeouts the timer forces a processor reset.
The DS1238 enables external override by debouncing the pushbutton input. A minimum active reset pulse width is provided.
An on-chip switch directs SRAM power between Vcc or an external battery, whichever is greater. This switched supply can also back up a CMOS microprocessor.
To enable write protection upon the detection of a power-fail condition, the chip enable output is held to within 0.3V Vcc or to within 0.7V of battery input.
Alternative oscillator control pins provide either external or internal clock timing for both the reset pulse width and the watchdog timeout period.

DS1238 MicroManagers are complete system monitors for SRAM, microprocessor software, and systems power. They provide power-on reset for smooth microprocessor reboots, convert CMOS SRAM to nonvolatile operation, and provide flexible timing controls. The extensive integration of functionality ensures reliable operation in battery-backed, processor-controlled systems while reducing component count, saving power, simplifying board layout, and saving cost and space.

关键特性

Power fail detect with referenced comparator, NMI:
- Warns microprocessor of an impending power failure
- Holds microprocessor in check during power transients
- Halts and restarts an out-of-control microprocessor
- Provides orderly shutdown in nonvolatile microprocessor applications
- Invokes sleep mode
Pushbutton reset:
- Monitors pushbutton for external override
- Controls external power switch for high-current applications
- Controls low-power stop mode in battery operated hand-held applications
Watchdog timer
5V operation with active high and low resets:
- ±5% of 5V (DS1238-5, DS1238A-5)
- ±10% of 5V (DS1238, DS1238A)
Battery switch:
- Converts CMOS SRAM into nonvolatile memory
Control pins gate to external power switch for high-current applications
CE control:
- Unconditionally write-protects memory when power supply is out of tolerance
Optional freshness mode (DS1238) seals battery until first power-on
Consumes less than 200nA of battery current at 25°C
Operating ranges:
- DS1238, DS1238A: 0°C to +70°C
- DS1238-IND, DS1238A-IND: -40°C to +85°C
Pin-for-pin compatibility with MAX691, MAX693, MAX695
Optional internal or external timing control

Key Specifications: Battery Backup Circuits

Part Number

Reset Threshold Range (V)

Active-Low Reset Output

Active-High Reset Output

Max. I_CC (µA)

Features

RoHS Available

Package

Operating Temp. Range (°C)

Price^**

DS1238

3.3 to 5.5

Open Drain

Push-Pull

4000

•	Chip Enable Gate

•	Manual Reset

•	Power Fail Comparator

•

Watchdog

Yes

PDIP/16
SOIC/16

-40 to +85
0 to +70

$3.65 @ 1k

See All Battery Backup Circuits (89)

Notes:
^**This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

定购信息

注：

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型号尾缀：T或T&R = 卷带; + = RoHS/无铅; # = RoHS/无铅豁免权。详细信息请参考：完整的数据资料或型号命名规则。
* “封装代码/变更”提供产品使用的变更信息。注意：型号尾缀中的“+”、“#”和“-”表示器件的RoHS状况，封装图上可能显示不同的尾缀字符。

器件： 1-15 of 15

DS1238

注

免费样品

采购

封装：	类型引脚占位面积
	封装图编码/变更 *

温度

RoHS/无铅？
材料分析

DS1238-5+

PDIP；16引脚；
封装图： 21-0043D (PDF)
使用封装码/变更：P16+2*

0°C至+70°C

RoHS/无铅：无铅
材料分析

DS1238-10+

PDIP；16引脚；
封装图： 21-0043D (PDF)
使用封装码/变更：P16+2*

0°C至+70°C

RoHS/无铅：无铅
材料分析

DS1238-10N+

PDIP；16引脚；
封装图： 21-0043D (PDF)
使用封装码/变更：P16+2*

-40°C至+85°C

RoHS/无铅：无铅
材料分析

DS1238-10

5V-10%监测精度

PDIP；16引脚；
封装图： 21-0043D (PDF)
使用封装码/变更：P16-2*

0°C至+70°C

RoHS/无铅：否
材料分析

DS1238-5

5V-5%监测精度

PDIP；16引脚；
封装图： 21-0043D (PDF)
使用封装码/变更：P16-2*

0°C至+70°C

RoHS/无铅：否
材料分析

DS1238-10N

5V-10%监测精度

PDIP；16引脚；
封装图： 21-0043D (PDF)
使用封装码/变更：P16-2*

-40°C至+85°C

RoHS/无铅：否
材料分析

DS1238S/T&R/

SOIC；16引脚；
封装图： 21-0042B (PDF)
使用封装码/变更：W16-3*

0°C至+70°C

参考数据资料
材料分析

DS1238S-10+

SOIC；16引脚；
封装图： 21-0042B (PDF)
使用封装码/变更：W16+3*

0°C至+70°C

RoHS/无铅：无铅
材料分析

DS1238S-5+

SOIC；16引脚；
封装图： 21-0042B (PDF)
使用封装码/变更：W16+3*

0°C至+70°C

RoHS/无铅：无铅
材料分析

DS1238S/T&R

5V-10%

SOIC；16引脚；
封装图： 21-0042B (PDF)
使用封装码/变更：W16-3*

0°C至+70°C

参考数据资料
材料分析

DS1238S-5/T&R

5V-5%

SOIC；16引脚；
封装图： 21-0042B (PDF)
使用封装码/变更：W16-3*

0°C至+70°C

RoHS/无铅：否
材料分析

DS1238S-5

5V-5%监测精度

SOIC；16引脚；
封装图： 21-0042B (PDF)
使用封装码/变更：W16-3*

0°C至+70°C

RoHS/无铅：否
材料分析

DS1238S-10

5V-10%监测精度

SOIC；16引脚；
封装图： 21-0042B (PDF)
使用封装码/变更：W16-3*

0°C至+70°C

RoHS/无铅：否
材料分析

DS1238S-5+T&R

SOIC；16引脚；
封装图： 21-0042B (PDF)
使用封装码/变更：W16+3*

0°C至+70°C

RoHS/无铅：无铅
材料分析

DS1238S+T&R

SOIC；16引脚；
封装图： 21-0042B (PDF)
使用封装码/变更：W16+3*

0°C至+70°C

参考数据资料
材料分析