ST STM6321, STM6322, STM6821, STM6822, STM6823 User Manual

STM6321, STM6322, STM6821, STM6822, STM6823, STM6824, STM6825

5-pin supervisor with watchdog timer and push-button reset

Features

■Precision VCC monitoring of 5, 3.3, 3, or 2.5 V power supplies

■RST outputs (active low, push-pull or open drain)

■RST outputs (active high, push-pull)

■Reset pulse width of 1.4 ms, 200 ms and 240 ms (typ.)

■Watchdog timeout period of 1.6 s (typ.)

■Manual reset input (MR)

■Low supply current - 3 µA (typ.)

■Guaranteed RST (RST) assertion down to VCC = 1.0 V

■Operating temperature: –40 to +85 °C (industrial grade)

■RoHS compliance

Lead-free components are compliant with the RoHS directive

Datasheet −production data

SOT23-5 (WY)

Table 1. Device summary

					Reset output
	Part number	Watchdog input	Manual reset
				Active low	Active high	Active low
			input
				(push-pull)	(push-pull)	(open drain)
	STM6321
	STM6322
	STM6821
	STM6822
	STM6823
	STM6824
	STM6825

June 2012

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This is information on a product in full production.

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Contents	STM6321, STM6322, STM6821, STM6822, STM6823, STM6824, STM6825

Contents

1	Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		5
	1.1	Pin descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	7

1.1.1 Active low, push-pull reset output (RST) - 6823/6824/6825 . . . . . . . . . . . 7 1.1.2 Active low, open drain reset output (RST) - STM6321/6322/6822 . . . . . . 7 1.1.3 Push-button reset input (MR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.1.4 Watchdog input (WDI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.1.5 Active high reset output (RST) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

2	Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .				10
	2.1	Reset output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .			10
	2.2	Open drain		output	10
			RST
	2.3	Push-button reset input (STM6322/6821/6822/6823/6825) . . . . . . . . . . .			11
	2.4	Watchdog input (STM6321/6821/6822/6823/6824) . . . . . . . . . . . . . . . . .			11
	2.5	Applications information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .			11

2.5.1 Watchdog input current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.5.2 Ensuring a valid reset output down to VCC = 0 V . . . . . . . . . . . . . . . . . . 11

2.6 Interfacing to microprocessors with bidirectional reset pins . . . . . . . . . . . 12

3	Typical operating characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	13
4	Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	18
5	DC and AC parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	19
6	Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	21
7	Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	24
8	Part numbering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	27
9	Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	30

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STM6321, STM6322, STM6821, STM6822, STM6823, STM6824, STM6825	List of tables

List of tables

Table 1. Device summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Table 2. Signal names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Table 3. Pin functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Table 4. Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Table 5. Operating and AC measurement conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Table 6. DC and AC characteristic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Table 7. SOT23-5 – 5-lead small outline transistor package mechanical data. . . . . . . . . . . . . . . . . 25 Table 8. Carrier tape dimensions for SOT23-5 package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Table 9. Ordering information scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Table 10. Marking description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Table 11. Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

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List of figures	STM6321, STM6322, STM6821, STM6822, STM6823, STM6824, STM6825

List of figures

Figure 1. Logic diagram (STM6821/6822/6823) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Figure 2. Logic diagram (STM6321/6322/6824/6825) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Figure 3. STM6822/6823 SOT23-5 connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Figure 4. STM6821 SOT23-5 connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Figure 5. STM6322/6825 SOT23-5 connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Figure 6. STM6321/6824 SOT23-5 connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Figure 7. Block diagram (STM6821/6822/6823) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Figure 8. Block diagram (STM6321/6824) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Figure 9. Block diagram (STM6322/6825) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Figure 10. Hardware hookup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Figure 11. STM6321/6322/6822 open drain RST output with multiple supplies . . . . . . . . . . . . . . . . . 10

Figure 12. Ensuring RST valid to VCC = 0, (active low push-pull outputs). . . . . . . . . . . . . . . . . . . . . . 12 Figure 13. Ensuring RST valid to VCC = 0, (active high, push-pull outputs) . . . . . . . . . . . . . . . . . . . . 12

Figure 14. Interfacing to microprocessors with bidirectional reset I/O . . . . . . . . . . . . . . . . . . . . . . . . . 12

Figure 15. VCC-to-reset output delay vs. temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Figure 16. Supply current vs. temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Figure 17. MR-to-reset output delay vs. temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Figure 18. Normalized power-up trec vs. temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Figure 19. Normalized reset threshold voltage vs. temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Figure 20. Normalized power-up watchdog timeout period . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Figure 21. Voltage output low vs. ISINK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Figure 22. Voltage output high vs. ISOURCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Figure 23. Maximum transient duration vs. reset threshold overdrive . . . . . . . . . . . . . . . . . . . . . . . . . 17 Figure 24. AC testing input/output waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Figure 25. MR timing waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Figure 26. Watchdog timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Figure 27. SOT23-5 – 5-lead small outline transistor package mechanical drawing . . . . . . . . . . . . . . 25 Figure 28. Carrier tape for SOT23-5 package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

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STM6321, STM6322, STM6821, STM6822, STM6823, STM6824, STM6825	Description

1 Description

The STM6xxx supervisors are self-contained devices which provide microprocessor supervisory functions. A precision voltage reference and comparator monitors the VCC input for an out-of-tolerance condition. When an invalid VCC condition occurs, the reset output

(RST) is forced low (or high in the case of RST). These devices also offer a watchdog timer (except for STM6322/6825) and/or a push-button (MR) reset input.

These devices are available in a standard 5-pin SOT23 package.

Figure 1. Logic diagram (STM6821/6822/6823)

VCC

WDI

STM6XXX

RST (RST)(1)

MR

VSS

AI09128

1. For STM6821 only.

Figure 2.

Logic diagram (STM6321/6322/6824/6825)

VCC

RST

(WDI)(1)

STM6XXX

MR

RST

VSS

AI09129

1. For STM6321/6824.

Table 2.

Signal names

Name

Function

Push-button reset input

MR

WDI

Watchdog input

Active low reset output

RST

RST

Active high reset output

VCC

Supply voltage

VSS

Ground

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Description	STM6321, STM6322, STM6821, STM6822, STM6823, STM6824, STM6825
	Figure 3. STM6822/6823 SOT23-5 connections
						SOT23-5
				(1)				VCC
		RST				1	5
		VSS				2
			MR			3	4	WDI
								AI09130a

1. Open drain for STM6822.

Figure 4. STM6821 SOT23-5 connections

			SOT23-5
RST(1)					VCC
			1	5
VSS			2
	MR		3	4	WDI
					AI12285

1. Push-pull only.

Figure 5. STM6322/6825 SOT23-5 connections

			SOT23-5
		(1)
	RST		1	5	VCC
	VSS		2
RST(2)			3	4	MR
					AI09131a

1.Open drain for STM6322.

2.Push-pull only.

Figure 6. STM6321/6824 SOT23-5 connections

			SOT23-5
	RST	(1)	1	5	VCC
	VSS		2
RST(2)			3	4	WDI
					AI12286

1.Open drain for STM6321.

2.Push-pull only.

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STM6321, STM6322, STM6821, STM6822, STM6823, STM6824, STM6825	Description

1.1Pin descriptions

1.1.1Active low, push-pull reset output (RST) - 6823/6824/6825

Pulses low when triggered, and stays low whenever VCC is below the reset threshold or

when MR is a logic low. It remains low for trec after either VCC rises above the reset threshold, the watchdog triggers a reset, or MR goes from low to high.

1.1.2Active low, open drain reset output (RST) - STM6321/6322/6822

Pulses low when triggered, and stays low whenever VCC is below the reset threshold or

when MR is a logic low. It remains low for trec after either VCC rises above the reset threshold, the watchdog triggers a reset, or MR goes from low to high. Connect a pull-up resistor to supply voltage.

1.1.3Push-button reset input (MR)

A logic low on MR asserts the reset output. Reset remains asserted as long as MR is low

and for trec after MR returns high. This active low input has an internal 52 kΩ pull-up. It can be driven from a TTL or CMOS logic line, or shorted to ground with a switch. Leave open if

unused.

1.1.4Watchdog input (WDI)

If WDI remains high or low for at least 1.6 s, the internal watchdog timer expires and reset is asserted. The internal watchdog timer clears while reset is asserted or when WDI sees

a rising or falling edge. The watchdog function CAN be disabled if WDI is left unconnected or is connected to a tristate buffer output.

1.1.5Active high reset output (RST)

Active high, push-pull reset output; inverse of RST.

Table 3.	Pin functions
	Pin
					Name					Function
STM6822			STM6321	STM6322
	STM6821
STM6823			STM6824	STM6825
1	—		1	1						Active low reset output
						RST
3	3		—	4						Push-button reset input
							MR
4	4		4	—		WDI				Watchdog Input
—	1		3	3		RST				Active high reset output
5	5		5	5		VCC				Supply voltage
2	2		2	2		VSS				Ground

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Description	STM6321, STM6322, STM6821, STM6822, STM6823, STM6824, STM6825

Figure 7. Block diagram (STM6821/6822/6823)

7$)

7!4#($/'

7$)

TRANSITIONAL

4)-%2

DETECTOR

6##

TREC

6234 #/-0!2%

2343 234

6##

GENERATOR

-2

!) 6

1.Push-pull for STM6823, open drain for STM6822.

2.Active high (push-pull) for STM6821.

Figure 8. Block diagram (STM6321/6824)

	7$)	7!4#($/'
7$)	TRANSITIONAL
		4)-%2
	DETECTOR
6##	6234	#/-0!2%	TREC	234
			GENERATOR	234
				! 6

3.Active low (open drain) for STM6321, active low (push-pull) for STM6824.

4.Push-pull only.

Figure 9. Block diagram (STM6322/6825)

6##		#/-0!2%	TREC	234
6##	6234
			GENERATOR	234
-2
				!) 6

1.Active low (open drain) for STM6322, active low (push-pull) for STM6825.

2.Push-pull only.

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STM6321, STM6322, STM6821, STM6822, STM6823, STM6824, STM6825	Description

Figure 10. Hardware hookup

6##

6##

34888

&ROMOMICROPROCESSOR 7$)

-2

0USH BUTTON		4OOMICROPROCESSOR RESET
2343 234

234 4OOMICROPROCESSOR RESET

!) 6

1.For STM6321/6821/6822/6823/6824.

2.For STM6322/6821/6822/6823/6825.

3.For STM6821/ (RST output only).

4.For STM6321/6322/6824/6825 (both RST and RST outputs).

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Operation	STM6321, STM6322, STM6821, STM6822, STM6823, STM6824, STM6825

2 Operation

2.1Reset output

The STM6xxx supervisor asserts a reset signal to the MCU whenever VCC goes below the reset threshold (VRST), a watchdog timeout occurs, or when the push-button reset input

(MR) is taken low. Reset is guaranteed valid for VCC < VRST down to VCC =1 V for TA = 0 to 85 °C.

During power-up, once VCC exceeds the reset threshold an internal timer keeps reset low for the reset timeout period, trec. After this interval reset is de-asserted.

Each time RST is asserted, it stays low for at least the reset timeout period (trec). Any time VCC goes below the reset threshold the internal timer clears. The reset timer starts when VCC returns above the reset threshold.

2.2Open drain RST output

The STM6321/6322/6822 have an active low, open drain reset output. This output structure will sink current when RST is asserted. Connect a pull-up resistor from RST to any supply voltage up to 6 V (see Figure 11). Select a resistor value large enough to register a logic low, and small enough to register a logic high while supplying all input current and leakage paths connected to the reset output line. A 10 kΩ pull-up resistor is sufficient in most applications.

Figure 11. STM6321/6322/6822 open drain RST output with multiple supplies

6				6
6##
34888				66SYSTEM
	-2
7$)
234
234
'.$

!) 6

1.STM6322/6822.

2.STM6321/6822.

3.STM6321/6322.

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