MAX811/MAX812
8)Tsm(7A = +25°C NOIT6ARUD5MAX81 _L/M TNEI4SNAR3MAX81 _R/S/TT MUM2IXAM101101001000RESET COMPARATOR OVERDRIVE, VTH - VCC (mV)Figure 1. Maximum Transient Duration without Causing a Reset Pulse vs. Comparator Overdrive
Applications Information
Negative-Going VCC Transients
In addition to issuing a reset to the μP during power-up, power-down, and brownout conditions, the MAX811/MAX812 are relatively immune to short duration negative-going VCC transients (glitches).
Figure 1 shows typical transient durations vs. reset com-parator overdrive, for which the MAX811/MAX812 do not generate a reset pulse. This graph was generated using a negative-going pulse applied to VCC, starting above the actual reset threshold and ending below it by the magnitude indicated (reset comparator overdrive). The graph indicates the typical maximum pulse width a negative-going Va reset pulse to be issued. As the magnitude of the tranCC transient may have without causing -sient increases (goes farther below the reset threshold), the maximum allowable pulse width decreases. Typically, a Vold and lasts 40μs or less (MAX81_L/M) or 20μs or less CC transient that goes 125mV below the reset thresh-(MAX81_T/S/R) will not cause a reset pulse to be issued. A 0.1μF capacitor mounted as close as possible to Vprovides additional transient immunity.
CC 4-Pin μP Voltage Monitorswith Manual Reset Input
VCCMAX811RESETR1GNDFigure 2. RESET Valid to VCC = Ground Circuit
Ensuring a Valid Down to VRESET OutputCC = 0V
When VCC falls below 1V, the MAX811 RESET output no longer sinks current—it becomes an open circuit. Therefore, high-impedance CMOS-logic inputs connected to the RESET output can drift to undetermined voltages. This presents no problem in most applications, since most μP and other circuitry is inoperative with VHowever, in applications where the RESETCC below 1V. output must be valid down to 0V, adding a pulldown resistor to the RESET pin will cause any stray leakage currents to flow to ground, holding RESET low (Figure 2). R1’s value is not critical; 100kΩ is large enough not to load RESET and small enough to pull RESET to ground.
A 100kΩ pull-up resistor to VCC is also recommended for the MAX812 if RESET is required to remain valid for VCC < 1V.
MAX811/MAX812
4-Pin μP Voltage Monitorswith Manual Reset Input
Absolute Maximum Ratings
Terminal Voltage (with respect to GND) VCC .....................................................................-0.3V to 6.0V All Other Inputs .....................................-0.3V to (VCC + 0.3V)Input Current, VCC, MR ......................................................20mAOutput Current, RESET or RESET ....................................20mAContinuous Power Dissipation (TA = +70°C)
SOT143 (derate 4mW/°C above +70°C) .....................320mW
Operating Temperature Range ...........................-40°C to +85°CJunction Temperature ......................................................+150°CStorage Temperature Range ............................-65°C to +160°CLead Temperature (soldering, 10sec) .............................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
Electrical Characteristics
(VCC = 5V for L/M versions, VCC = 3.3V for T/S versions, VCC = 3V for R version, TA = -40°C to +85°C, unless otherwise noted.Typical values are at TA = +25°C.) (Note 1)
PARAMETER
Operating Voltage RangeSupply Current
SYMBOLVCCICC
CONDITIONS
TA = 0°C to +70°CTA = -40°C to +85°C
MAX81_L/M, VCC = 5.5V, IOUT = 0MAX81_R/S/T, VCC = 3.6V, IOUT = 0MAX81_LMAX81_M
Reset Threshold
VTH
MAX81_TMAX81_SMAX81_R
Reset Threshold TempcoVCC to Reset Delay (Note 2)Reset Active Timeout PeriodMR Minimum Pulse WidthMR Glitch Immunity (Note 3)MR to Reset Propagation Delay (Note 2)
tMDVIH
MR Input Threshold
VILVIHVIL
MR Pull-Up Resistance
VOH
RESET Output Voltage (MAX812)
VOL
ISOURCE = 150μA, 1.8V < VCC < VTH(MIN)MAX812R/S/T only, ISINK = 1.2mA, VCC = VTH(MAX)
MAX812L/M only, ISINK = 3.2mA, VCC = VTH(MAX)
VCC > VTH(MAX), MAX81_L/MVCC > VTH(MAX), MAX81_R/S/T
2.3
0.8
0.7 x VCC
0.25 x VCC
100.8 x VCC
0.30.4
V
20
30
k?V
tRPtMR
VOD = 125mV, MAX81_L/MVOD = 125mV, MAX81_R/S/TVCC = VTH(MAX)
14010
1000.5
TA = +25°CTA = -40°C to +85°CTA = +25°CTA = -40°C to +85°CTA = +25°CTA = -40°C to +85°CTA = +25°CTA = -40°C to +85°CTA = +25°CTA = -40°C to +85°C
4.544.504.304.253.033.002.882.852.582.55
304020
560
2.632.933.084.38
MIN1.01.2
62.74.63
15104.724.754.464.503.143.152.983.002.682.70
ppm/°CμsmsμsnsμsV
TYP
MAX5.5
UNITSVμA
MEMORY存储芯片MAX868EUB中文规格书 - 图文
