STM809, STM810 STM811, STM812 Reset circuit Features ■ Precision monitoring of 3 V, 3.3 V, and 5 V supply voltages ■ Two output configurations – Push-pull RST output (STM809/811) – Push-pull RST output (STM810/812) ■ 140 ms reset pulse width (min) ■ Low supply current - 6 µA (typ) ■ Guaranteed RST/RST assertion down to VCC = 1.0 V ■ Operating temperature: –40 °C to 85 °C (industrial grade) ■ Lead-free, small SOT23 and SOT143 package Table 1.
Contents STM809/810/811/812 Contents 1 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.1 Reset output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.2 Push-button reset input (STM811/812) . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.
STM809/810/811/812 List of tables List of tables Table 1. Table 2. Table 3. Table 4. Table 5. Table 6. Table 7. Table 8. Table 9. Table 10. Device summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Signal names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
List of figures STM809/810/811/812 List of figures Figure 1. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. Figure 8. Figure 9. Figure 10. Figure 11. Figure 12. Figure 13. Figure 14. Figure 15. Figure 16. 4/21 Logic diagram (STM809/810) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Logic diagram (STM811/812) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 SOT23-3 connections . . . . . . . .
STM809/810/811/812 1 Description Description The STM809/810/811/812 microprocessor reset circuits are low-power supervisory devices used to monitor power supplies. They perform a single function: asserting a reset signal whenever the VCC supply voltage drops below a preset value and keeping it asserted until VCC has risen above the preset threshold for a minimum period of time (trec). The STM811/812 also provide a push-button reset input (MR). Figure 1.
Description STM809/810/811/812 Figure 3. SOT23-3 connections VSS 1 2 RST (RST) 3 VCC (For STM810) Figure 4. AI07833 SOT143-4 connections VSS 1 2 RST (RST) 4 3 VCC MR (For STM812) AI07834 Figure 5. Block diagram VCC VRST COMPARE trec Generator MR(1) RST(2) DEBOUNCE AI07835 1. STM811/812 only 2. RST for STM810/812 Figure 6. Hardware hookup VCC VCC VCC STM809/810/ 811/812 MCU MR(2) (1) RST Push-button RESET VSS RESET Input VSS AI07836 1.
STM809/810/811/812 2 Operation 2.1 Reset output Operation The STM809/810/811/812 microprocessor reset circuit asserts a reset signal to the MCU whenever VCC goes below the reset threshold (VRST), or when the push-button reset input (MR) is taken low (see Figure 14 on page 13). RST (active high for STM810/812) is guaranteed valid down to VCC = 1 V (0° to 70°C). During power-up, once VCC exceeds the reset threshold an internal timer keeps RST low for the reset time-out period, trec.
Operation 2.4 STM809/810/811/812 Valid RST output down to VCC = 0 V When VCC falls below 1 V, the RST (STM809/811) output no longer sinks current, but becomes an open circuit. In most systems this is not a problem, as most MCUs do not operate below 1 V. However, in applications where RST output must be valid down to 0 V, a pull-down resistor may be added to hold the RST output low. This resistor must be large enough to not load the RST output, and still be small enough to pull the output to ground.
STM809/810/811/812 Typical operating characteristics 3 Typical operating characteristics Note: Typical values are at TA = 25 °C, VCC = 5 V for L/M versions, VCC = 3.3 V for T/S versions, and VCC = 3.0 V for R versions. Figure 7. Supply current vs. temperature, L/M/R/S/T (no load) 8.0 Supply Current (µA) 6.0 1V 3V 3.6V 5.5V 4.0 2.0 0.0 –40 –20 0 20 40 60 80 Temperature (°C) AI07879 Power-down reset delay vs. temperature - VOD = VTH – VCC (L/M) 140.00 120.
Typical operating characteristics Figure 9. STM809/810/811/812 Power-down reset delay vs. temperature - VOD = VTH – VCC (R/S/T) Power-Down Reset Delay (µs) 100.00 80.00 60.00 VOD = 20mV VOD = 125mV VOD = 200mV 40.00 20.00 0.00 –40 –20 0 20 40 60 80 Temperature (°C) AI07878 Figure 10. Power-up trec vs. temperature 250.00 Power-up trec (ms) 240.00 230.00 L/M R/S/T 220.00 210.00 200.
STM809/810/811/812 Figure 11. Typical operating characteristics Normalized reset threshold vs. temperature 1.003 1.002 1.001 Normalized Threshold 1.000 0.999 0.998 L/M R/S/T 0.997 0.996 0.995 0.994 0.993 –40 –20 0 20 40 60 80 Temperature (°C) AI07882 Figure 12. Max transient duration NOT causing reset pulse vs. reset comparator overdrive 700.00 Maximum Transient Duration (µs) 600.00 500.00 400.00 R/S/T L/M 300.00 200.00 100.00 0.
Maximum ratings 4 STM809/810/811/812 Maximum ratings Stressing the device above the rating listed in the absolute maximum ratings table may cause permanent damage to the device. These are stress ratings only and operation of the device at these or any other conditions above those indicated in the operating sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
STM809/810/811/812 5 DC and AC parameters DC and AC parameters This section summarizes the operating measurement conditions, and the DC and AC characteristics of the device. The parameters in the DC and AC characteristics tables that follow, are derived from tests performed under the measurement conditions summarized in Table 4.. Designers should check that the operating conditions in their circuit match the operating conditions when relying on the quoted parameters. Table 4.
DC and AC parameters Table 5. Sym DC and AC characteristics Alternative Description VCC Operating voltage ICC VCC supply current VIH MR input high voltage VIL MR input low voltage VOL RST output low voltage (active high(2) or low) VOL STM809/810/811/812 RST output low voltage RST output high voltage VOH RST output high voltage Test condition(1) Min 1.2 TA = –40 to +85 °C TA = 0 to +70 °C 1.0 VCC < 3.6 V VCC < 5.5 V 2.2 VCC > VRST (max), STM8XXL/M VCC > VRST (max), STM8XXR/S/T 0.
STM809/810/811/812 Sym Alternative Description DC and AC parameters Test condition(1) Min Typ Max Unit Push-button reset input tMLMH tMR tMLRL tMRD trec MR pulse width MR to RST output delay(3) MR glitch immunity(4) MR pull-up resistance RST pulse width 10 µs 0.5 10 140 1. Valid for ambient operating temperature: TA = –40 to 85 °C; VCC = 1.2 V to 5.5 V (except where noted). 2. For active high (RST); VCC = VRST (max) 3. RST output for STM810/812 4.
Package mechanical data 6 STM809/810/811/812 Package mechanical data In order to meet environmental requirements, ST offers these devices in different grades of ECOPACK® packages, depending on their level of environmental compliance. ECOPACK® specifications, grade definitions and product status are available at: www.st.com. ECOPACK® is an ST trademark. Figure 15. SOT23-3 – 3-lead small outline transistor package outline E E1 0.15 B M CAB A1 1 e e1 D 0.20 M 3X CAB 0.
STM809/810/811/812 Package mechanical data Figure 16. SOT143-4 – 4-lead small outline transistor package outline E E1 0.15 B M CAB A1 1 e/2 e1 e D 0.15 M CAB b2 0.20 M 4X CAB C 0.10 A 3X b A2 C A C L1 C L Note: SOT143-4 Drawing is not to scale. Table 7. Symbol SOT143-4 – 4-lead small outline transistor package mechanical data mm Typ inches Min Max A 0.89 A1 Typ Min Max 1.12 0.035 0.044 0.01 0.10 0.001 0.004 A2 0.88 1.02 0.035 0.042 b 0.37 0.51 0.
Part numbering 7 STM809/810/811/812 Part numbering Table 8. Ordering information scheme Example: STM8XX L WX 6 F Device type STM8XX Reset threshold voltage L = VRST = 4.50 V to 4.75 V M = VRST = 4.25 V to 4.50 V T = VRST = 3.00 V to 3.15 V S = VRST = 2.85 V to 3.00 V R = VRST = 2.55 V to 2.70 V Package WX = SOT23-3 (STM809, STM810) W1 = SOT143-4 (STM811, STM812) Temperature range 6 = –40 to 85 °C Shipping method F = ECOPACK® package, tape & reel For a list of available options (e.g.
STM809/810/811/812 Table 9. Part numbering Marking description Part number Reset threshold Output Topside marking(1) STM809L 4.63 V Push-pull RST 8AAx STM809M 4.38 V Push-pull RST 8ABx STM809T 3.08 V Push-pull RST 8ACx STM809S 2.93 V Push-pull RST 8ADx STM809R 2.63 V Push-pull RST 8AEx STM810L 4.63 V Push-pull RST 8AFx STM810M 4.38 V Push-pull RST 8AGx STM810T 3.08 V Push-pull RST 8AHx STM810S 2.93 V Push-pull RST 8AJx STM810R 2.
Revision history 8 STM809/810/811/812 Revision history Table 10. 20/21 Document revision history Date Revision Changes 02-Sep-2003 1 03-Oct-2003 1.1 Update operating characteristics (Figure 7, Figure 8, Figure 9, Figure 10, Figure 11, Figure 12) 16-Oct-2003 1.2 Update characteristics (Table 5); modify illustration (Figure 12) 17-Nov-2003 1.3 Modified with JEDEC timing symbols (Figure 14;Table 5) 04-Dec-2003 2 Reformatted; promoted; updated (Figure 14; Table 5, 6) 09-Dec-2003 2.
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