HN809 / HN Pin Microprocessor Reset Monitors

Transcription

1 3-Pin Microprocessor Reset Monitors Product Description The HN809/810 microprocessor supervisory circuits can be used to monitor the power supplies in microprocessor and digital systems. They provide a reset to the microprocessor during power-up, power-down and brown-out conditions. The function of the HN809/810 is to monitor the CC supply voltage, and assert a reset signal whenever this voltage declines below the factory-programmed reset threshold. The reset signal remains asserted until CC has risen above for a minimum period of time. The HN809 has an active-low output, while the HN810 has an active-high output. Seven standard reset voltage options are available, suitable for monitoring 5, 3.3, and 3 supply voltages. With a low supply current of only 15 A, the HN809/810 are ideal for use in portable equipment. The HN809/HN810 are available in the 3-pin SOT3 package. Features Precise monitoring of 3, 3.3, and 5 supply voltages Superior upgrade to MAX809/810 Fully specified over temperature Guaranteed Output valid for CC 1 Active-low Output (HN809) Active-high Output (HN810) Low Supply Current. Power supply transient immunity Pin Configuration NOTE: 1 SOT3-3 (Top iew) 3 is for HN809 is for HN810 CC Pin Descriptions Applications Microprocessor Systems Computers Controllers Intelligent Instruments Portable/Battery-Powered Equipment Automotive Pin No. Name Pin Function 1 Ground reference Active-low output. remains low while (HN809) CC is below the reset threshold, and for a minimum period of time after CC rises above the reset threshold. (HN810) Active-high output. remains high while CC is below the reset threshold, and for a minimum period of time after CC rises above the reset threshold. 3 CC Supply oltage (+5, +3.3, or +3.0) Typical Application Circuit CC CC HN809/810 CC PROCESSOR INPUT Order and Threshold Information TH () HN809 Series HN810 Series Package.45 HN809M-.45 HN810M HN809M-.63 HN810M HN809M-.93 HN810M HN809M-3.08 HN810M-3.08 SOT HN809M-4.00 HN810M HN809M-4.38 HN810M HN809M-4.63 HN810M

2 Absolute Maximum Ratings (Note 1) CC to 7.0, to ( CC + ) Input Current, CC Pin mA Output Current,, Pin mA Continuous Power Dissipation (Note 3) mW JA, SOT C/W Ambient Temperature Range C to +85 C Storage Temperature Range C to +150 C Lead Temperature (soldering, 10sec) C Electrical Characteristics CC = full range, T A = 40 C to +85 C, unless otherwise noted. Typical values are at T A = +5 C, CC =5 for 4.63/4.38 versions, CC = 3.3 for 3.08/.93 versions, and CC = 3 for.63 version (Note ). Symbol Parameter Conditions Min Typ Max Units CC Range T A =0 C to +70 C T A = 40 C to +85 C I CC Supply Current T A = 40 C to 85 C HN CC =5.5, HN8-4.63/4.38/4.00 T A =+5 C CC =3.6, HN8-3.08/.93/.63/.45 T A = 40 C to 85 C A HN T A =+5 C T A = 40 C to 85 C TH Reset Threshold (Note 4) HN T A =+5 C T A = 40 C to 85 C HN T A =+5 C T A = 40 C to 85 C HN T A =+5 C T A = 40 C to 85 C Reset Threshold Temperature Coefficient 45 ppm/ C CC to Reset Delay (Note 4) CC = TH to ( TH 100m) 0 s OL CC = TH min, I SINK = 1.mA, HN /.93/3.08 Output oltage Low (HN809) CC = TH min, I SINK =3.mA, HN /4.38 CC >1.0, I SINK =50 A 0.4 OH OL Output oltage High (HN809) Output oltage Low (HN810) CC > TH max, I SOURCE =500 A, HN /.93/3.08 CC = TH max, I SINK =1.mA, HN /.93/ CC CC > TH max, I SOURCE =800 A, HN /4.38 CC = TH max, I SINK =3.mA, HN /4.38 CC OH Output oltage High (HN810) 1.8 < CC < TH min, I SOURCE =150 A 0.8 CC Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which the device operates correctly. Operating ratings do not imply guaranteed performance limits. For guaranteed performance limits and associated test conditions, see the Electrical Characteristics. Note : Production testing done at TA = +5 C, over temperature limits guaranteed by design only. Note 3: At elevated temperatures, devices must be derated based on package thermal resistance. The device in the SOT3-3 package must be derated at 4mW/ C at ambient temperatures above 70 C. The device has internal thermal protection. Note 4: Output for HN809, output for HN810.

3 Typical Performance Characteristics Supply Current (µa) 8,0 7,0 6,0 5,0 4,0 Supply Current vs. Temperature cc=5.5 cc=3.6 Reset Threshold (),95,94,93,9,91 Reset Threshold vs. Temperature (HN ) 3,0,90 Output Low oltage () 0,05 0,04 0,03 0,0 0,01 Output Low oltage vs. Temperature ( CC =,85, I OL =1,mA) 0 Output High oltage () 3,3 3, 3,1 3,0 3,19 Output High oltage vs. Temperature ( CC =3,3, I OH =500μA) 3,18 3

4 Applications Information Benefits of Precision Reset Thresholds A microprocessor supply supervisor must provide a reset output within a predictable range of the supply voltage. A common threshold range is between 5% and 10% below the nominal supply voltage. The 4.63 and 3.08 options of the HN809/810 use highly accurate circuitry to ensure that the reset threshold occurs only within this range (for 5 and 3.3 supplies). The other voltage options have the same tight tolerance to ensure a reset signal for other narrow monitor ranges. See Table 1 for examples of how the standard reset thresholds apply to 3, 3.3, and 5 nominal supply voltages. TABLE 1. Reset Thresholds Related to Common Supply oltages Reset Threshold HN ± 3% 90-95% 4.38 ± 3% 85-90% 3.08 ± 3% 90-95%.93 ± 3% 86-90% ± 3% 85-90% 77-81% FIGURE 1. alid to CC = Ground Circuit Ensuring a alid Reset Output Down to CC = 0 When CC falls below 1, the HN809 output no longer sinks current. A high-impedance CMOS logic input connected to can therefore drift to undetermined voltages. To prevent this situation, a 100kΩ resistor should be connected from the output to ground, as shown in Figure 1. A 100k pull-up resistor to CC is also recommended for the HN810, if is required to remain valid for CC < 1. HN8 -.63/.93/3.08 HN8-4.38/4.63 HN809 FIGURE. Maximum Transient Duration without Causing a Reset Pulse vs. Reset Comparator Overdrive FIGURE 3. Interfacing to Microprocessors with Bidirectional Reset I/O Negative-Going CC Transients The HN809/810 are relatively immune to short negative-going transients or glitches on CC. Figure shows the maximum pulse width a negative-going CC transient can have without causing a reset pulse. In general, as the magnitude of the transient increases, going further below the threshold, the maximum allowable pulse width decreases. Typically, for the 4.63 and 4.38 version of the HN809/810, a CC transient that goes 100m below the reset threshold and lasts 0 s or less will not cause a reset pulse. A 0.1 F bypass capacitor mounted as close as possible to the CC pin will provide additional transient rejection. Interfacing to Ps with Bidirectional Reset Pins Microprocessors with bidirectional reset pins, such as the Motorola 68HC11 series, can be connected to the HN809 output. To ensure a correct output on the HN809 even when the microprocessor reset pin is in the opposite state, connect a 4.7k resistor between the HN809 output and the P reset pin, as shown in Figure 3. Buffer the HN809 output to other system components. 4

5 Physical Dimensions inches (millimeters) unless otherwise noted 3-Lead SOT3-3 For Ordering, refer to Ordering Information table 5