DIDES APX811/812 4-Pin Microprocessor Supervisor User Manual

DIDES APX811/812 4-Pin Microprocessor Supervisor

Features

• Precision Monitor of(2.5V/3.0V/3.3V/5.0V) power supply voltage
• Full specified over temperature
• Manual reset input
• Available in four output configuration
• Push-pull RESET Active low(APX811)
• Push-pull RESET Active high(APX812)
• Power-on reset generator with fixed delay time 200ms
• SOT143: Available in “Green” Molding Compound (No Br, Sb)
• Lead Free Finish/RoHS Compliant (Note 1)

General Description

The APX811/812 are used for microprocessor supervisory circuit to monitor the power supplies in These circuit perform a single function: they assert a reset signal whenever the Vcc supply voltage declines below a preset threshold, keeping it asserted for at least 240ms after Vcc has risen above the reset threshold. Reset thresholds suitable for operation with a variety of supply voltages are available. The APX811/812 have push-pull outputs.
The APX811 has an active low RESET output, while the APX812 has an active high RESET output.

The APX811/812 devices incorporate a manual reset input, MR .
A low level at MR causes RESET to become active.
The APX811/2 are targeted at 2.5V, 3V, 3.3V and 5V powered systems and are available with different threshold voltages to meet the exact needs of the system. They are available in the space saving SOT143 package and operate over the whole industrial temperature range, -40 to 85°C.

Applications

• Computers
• Controllers
• Intelligent It instruments
• Critical up and UC power Monitoring
• Portable/Battery powered Equipment
• Automotive

Typical Application Circuit

Ordering Information

Device| Package Code| Packaging (Note 2)| 7” Tape and Reel
---|---|---|---
Quantity| Part Number Suffix
APX811-XXUG-7| U| SOT143| 3000/Tape & Reel| -7
APX812-XXUG-7| U| SOT143| 3000/Tape & Reel| -7

Notes:

1. EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied. Please visit our website at
   http://www.diodes.com/products/lead_free.html.

2. Pad layout as shown on Diodes Inc. suggested pad layout document AP02001, which can be found on our website at http://www.diodes.com/datasheets/ap02001.pdf.

Pin Assignments

Pin Descriptions

H: for APX812
VCC| Operating Voltage Input
MR| Manual reset (Active Low)

Block Diagram

Absolute Maximum Ratings

Recommended Operating Conditions

Electrical Characteristics (TA = 25ºC)

TA= -40 to 85 oC unless otherwise note. Typical values are at TA=+25 oC.

Symbol| Parameter| Test Conditions| Min| Typ.| Max| Unit
---|---|---|---|---|---|---
VCC| VCC Range| | 1.0| | 5.5| V
ICC| Supply Current| Vth + 0.2V| | 30| 40| µA
Vth| Reset threshold| TA =25 oC.| 2.22| 2.25| 2.28| V
2.59| 2.63| 2.67| V
2.89| 2.93| 2.98| V
3.03| 3.08| 3.13| V
3.94| 4.00| 4.06| V
4.31| 4.38| 4.45| V
4.56| 4.63| 4.70| V
ts| Set-up Time| VCC = Vth to (Vth – 100mV)| | 20| | µs

VOL

|

RESET Output Voltage Low (APX811)

| VCC = Vth -0.2, ISINK = 1.2mA| | | 0.3|

V

VCC = Vth -0.2, ISINK = 3.2mA| | | 0.4
VCC > 1.0V, ISINK = 50uA| | | 0.3

VOH

|

RESET Output Voltage-High (APX811)

| VCC > Vth +0.2, ISOURCE = 500uA| 0.8VCC| | |

V

VCC > Vth +0.2, ISOURCE = 800uA| VCC –1.5| |
VOL| RESET Output Voltage-Low (APX812)| VCC = Vth +0.2, ISINK = 1.2mA| | | 0.3| V
VCC = Vth +0.2, ISINK = 3.2mA| | | 0.4
VOH| RESET Output Voltage-High (APX812)| 1.8V < VCC < Vth -0.2, ISOURCE = 150uA| 0.8 VCC| | | V
θJA| Thermal Resistance Junction-to-Ambient| SOT143 (Note 3)| | 240| | oC/W
θJC| Thermal Resistance Junction-to-Case| SOT143 (Note 3)| | 71| | oC/W

Notes: 3. Test condition for SOT143: Device mounted on FR-4 substrate, 1″*1″, 2oz, copper, single-sided, PC boards.

Timing requirements (TA=25oC)

Symbol| Parameter| Test Conditions| Min| Typ.| Max| Unit
---|---|---|---|---|---|---
tW| Pulse Width| at MR| VCC> Vth-+0.2V, VIL=0.3 ´VCC, VIH=0.7 ´VCC| 100| –| –| ns

Switching Characteristics (TA=25oC)

Symbol| Parameter| Test Conditions| Min| Typ.| Max| Unit
---|---|---|---|---|---|---
td| Delay Time| APX811/812| VCC> Vth-+0.2V,

See timing diagram

| 140| 200| 280| ms

tPHL

| ****

Propagation (Delay) Time, High-to-low-level Output

| ****

MR to RESET delay (APX811/812)

| VCC> Vth-+0.2V,

VIL=0.3 ´VCC, VIH=0.7 ´VCC

| ****

–

| ****

–

| ****

0.1

| ****

µs

**** VCC to RESET delay| VIL= Vth–0.2V, VIH= Vth-+0.2V| –| –| 25| µs
tPLH| Propagation (Delay) Time, Low-to-high-level Output| MR to RESET delay (APX811/812)| VCC> Vth-+0.2V,

VIL=0.3 ´VCC, VIH=0.7 ´VCC

| ****

–

| ****

–

| ****

0.1

| ****

µs

VCC to RESET delay (APX811/812)| VIL= Vth–0.2V, VIH= Vth-+0.2V| –| –| 25| µs

Timing Diagram

Typical Performance Characteristics

Application Information

A microprocessor’s (µP’s) reset input starts the µP in a known state. The APX811/812 asserts reset to prevent code-execution errors during power-up, power-down, or brownout conditions. They assert a reset signal whenever the VCC supply voltage declines below a preset threshold or the MR pin is brought low, keeping it asserted for at least 240ms after VCC has risen above the reset threshold. The APX811/812 have a push-pull output stage.
The APX811/812 reset output is guaranteed to be logic low for the APX811 and high the APX812 for VCC > 1V. Once VCC exceeds the reset threshold, an internal timer keeps RESET output low (and RESET high for the APX812) for the reset timeout period. After this interval, the APX811’s RESET output goes high (APX812’s RESET output goes low). If a brownout condition occurs (VCC dips below the reset threshold), the APX811’s RESET output goes low (APX812’s RESET output goes high). Any time VCC goes below the reset threshold, the internal timer resets to zero, and RESET goes low (RESET goes high). The internal timer starts after VCC returns above the reset threshold, and RESET remains low (RESET remains high) for the reset timeout period.

Ensuring a Valid Reset Output Down to VCC = 0
When VCC falls below 1V, the APX811 RESET no longer sinks current-— it becomes an open circuit. Therefore, high-impedance CMOS logic inputs connected to RESET can drift to undetermined voltages. This presents no problem in most applications since most
µP and other circuitry is inoperative with VCC below 1V. However, in applications where RESET must be valid down to 0V, adding a pull down resistor to RESET causes any stray leakage currents to flow to ground, holding RESET low. R1’s value is not critical; 100k is
large enough not to load RESET and small enough to pull RESET to ground.
For the APX812 if RESET is required to remain valid for VCC < 1V then a 100kΩ pull-up resistor between RESET and VCC is recommended.

Benefits of Highly Accurate Reset Threshold
Most µP supervisor ICs has reset threshold voltages between 5% and 10% below the value of nominal supply voltages. This ensures a reset will not occur within 5% of the nominal supply, but will occur when the supply is 10% below nominal. When using ICs rated at only the nominal supply ±5%, this leaves a zone of uncertainty where the supply is between 5% and 10% low, and where the reset may or may not be asserted.

Marking Information

(1) SOT143

Package Information (All Dimensions in mm)

(1) Package Type: SOT143

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Copyright © 2009, Diodes Incorporated
www.diodes.com

APX811/812 Rev. 2
DS31960
10 of 10
www.diodes.com
OCTOBER 2009 ©
Diodes Incorporated

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