MICREL MIC6315

MIC6315
Micrel
MIC6315
Open-Drain µP Reset Circuit
General Description
Features
The MIC6315 is an inexpensive reset generator circuit that
monitors power supplies in microprocessor based systems.
The function of this device is to assert a reset if either the
power supply drops below a designated reset threshold
level or /MR is forced low. Several different reset threshold
levels are available to accommodate 3V, 3.3V or 5V powered
systems.
The MIC6315 has an active low, open-drain /RESET output.
The reset output is guaranteed to remain asserted for a
minimum of either 20ms, 140ms, or 1100ms after VCC has
risen above the designed reset threshold level. The MIC6315
comes in a 4-pin SOT-143 package.
• Precision voltage monitor for 3V, 3.3V or 5V power supplies
• /RESET remains valid with VCC as low as 1V
• 5µA supply current
• 20ms, 140ms, or 1100ms minimum reset pulse widths
available
• Manual reset input
• 4-pin SOT-143 package
Typical Application
Applications
•
•
•
•
•
Portable equipment
Intelligent instruments
Critical microprocessor power monitoring
Printers/computers
Embedded controllers
VCC
VCC
VCC
10k
MIC6315
MR
µP
RESET
RESET
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
October 2005
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M9999-102005
MIC6315
Micrel
Ordering Information(1, 2)
Standard
Part Number
Marking
Pb-Free
Part Number
Marking
Nominal
VTH (V)
Min. tRST
(ms)
Operating
Temp. Range
Package
2.63
20
–40°C to +85°C
4-lead SOT-143
MIC6315-26D2U
NY
MIC6315-26D2UY
NY
MIC6315-29D2U
NM
MIC6315-29D2UY
NM
2.93
20
–40°C to +85°C
4-lead SOT-143
MIC6315-30D2U
N2
MIC6315-30D2UY
N2
3.00
20
–40°C to +85°C
4-lead SOT-143
MIC6315-31D2U
NF
MIC6315-31D2UY
NF
3.08
20
–40°C to +85°C
4-lead SOT-143
MIC6315-40D2U
NW
MIC6315-40D2UY
NW
4.00
20
–40°C to +85°C
4-lead SOT-143
MIC6315-41D2U
N6
MIC6315-41D2UY
N6
4.10
20
–40°C to +85°C
4-lead SOT-143
MIC6315-44D2U
NG
MIC6315-44D2UY
NG
4.38
20
–40°C to +85°C
4-lead SOT-143
MIC6315-46D2U
NQ
MIC6315-46D2UY
NQ
4.63
20
–40°C to +85°C
4-lead SOT-143
MIC6315-26D3U
NR
MIC6315-26D3UY
NR
2.63
140
–40°C to +85°C
4-lead SOT-143
MIC6315-29D3U
NP
MIC6315-29D3UY
NP
2.93
140
–40°C to +85°C
4-lead SOT-143
MIC6315-30D3U
N3
MIC6315-30D3UY
N3
3.00
140
–40°C to +85°C
4-lead SOT-143
MIC6315-31D3U
NU
MIC6315-31D3UY
NU
3.08
140
–40°C to +85°C
4-lead SOT-143
MIC6315-40D3U
N8
MIC6315-40D3UY
N8
4.00
140
–40°C to +85°C
4-lead SOT-143
MIC6315-41D3U
N5
MIC6315-41D3UY
N5
4.10
140
–40°C to +85°C
4-lead SOT-143
MIC6315-44D3U
NH
MIC6315-44D3UY
NH
4.38
140
–40°C to +85°C
4-lead SOT-143
MIC6315-46D3U
NX
MIC6315-46D3UY
NX
4.63
140
–40°C to +85°C
4-lead SOT-143
MIC6315-26D4U
NS
MIC6315-26D4UY
NS
2.63
1100
–40°C to +85°C
4-lead SOT-143
MIC6315-29D4U
NN
MIC6315-29D4UY
NN
2.93
1100
–40°C to +85°C
4-lead SOT-143
MIC6315-30D4U
N4
MIC6315-30D4UY
N4
3.00
1100
–40°C to +85°C
4-lead SOT-143
MIC6315-31D4U
2N
MIC6315-31D4UY
2N
3.08
1100
–40°C to +85°C
4-lead SOT-143
MIC6315-40D4U
M9
MIC6315-40D4UY
M9
4.00
1100
–40°C to +85°C
4-lead SOT-143
MIC6315-41D4U
M7
MIC6315-41D4UY
M7
4.10
1100
–40°C to +85°C
4-lead SOT-143
MIC6315-44D4U
NJ
MIC6315-44D4UY
NJ
4.38
1100
–40°C to +85°C
4-lead SOT-143
MIC6315-46D4U
NZ
MIC6315-46D4UY
NZ
4.63
1100
–40°C to +85°C
4-lead SOT-143
Notes:
1. All devices available in tape and reel only.
2. Parts not yet assigned an identification code are shown as “zz”. Contact Micrel for details. Minimum order may apply.
Pin Configuration
GND 1
4 VCC
MIC6315
3 MR
RESET 2
MIC6315-xxDyU 4-Lead SOT-143
Pin Description
Pin Number
Pin Name
Pin Function
1
GND
IC Ground Pin.
2
/RESET
3
/MR
4
VCC
M9999-102005
/RESET goes low if VCC falls below the reset threshold and remains asserted
for one reset timeout period after VCC exceeds the reset threshold.
Manual Reset Input. A logic low on /MR forces a reset. The reset will remain
asserted as long as /MR is held low and for one reset timeout period after /MR goes
high. This input can be shorted to ground via a switch or be driven by TTL or CMOS
logic. Float if unused.
Power Supply Input.
2
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MIC6315
Micrel
Absolute Maximum Ratings(1)
Operating Ratings(2)
Terminal Voltage
(VCC, /RESET) ........................................–0.3V to 6.0V
(/MR) ..........................................–0.3V to (VCC + 0.3V)
Rate of Rise (VCC) .................................................. 100V/µs
Input Current (VCC, /MR) ............................................ 20mA
Output Current (/RESET) ........................................... 20mA
Lead Temperature (soldering, 10 sec.) ...................... 300°C
Storage Temperature (TS) ......................... –65°C to 150°C
ESD Rating(3) ............................................................... 3kV
Operating Temperature Range ................... –40°C to +85°C
Input Voltage (/RESET) .................................... GND – 5.5V
Power Dissipation (TA = +70°C) .............................. 320mW
Electrical Characteristics
For typical values, VCC = 2.5V to 5.5V, TA = 25°C; bold values indicate –40°C ≤ TA ≤ +85°C; unless noted
Symbol
Parameter
VCC
Operating Voltage Range
ICC
Supply Current
VTH
Reset Voltage Threshold
tRST
Reset Timeout Period
VOL
/RESET Output Voltage
Condition
Min
Typ
1
VCC = 5.5V, no load
5
5.5
V
15
µA
5
10
µA
VTH
VTH+2.5%
V
44
ms
D3U
140
200
320
ms
D4U
1100
1500
Note 4
20
D2U
28
2500
ms
VCC ≥ 4.0V, ISINK = 3.2mA
0.4
V
0.3
V
VCC ≥ 1.0V, ISINK = 50µA
0.3
V
1
µA
/RESET deasserted
10
/MR Minimum Pulse Width
/MR to Reset Delay
µs
0.5
VIH
/MR Input Threshold
VTH > 4.0V
VIL
/MR Input Threshold
VTH > 4.0V
/MR Pull-Up Resistance
Units
VTH–2.5%
VCC = 3.6V, no load
VCC > 2.5V, ISINK = 1.2mA
/RESET Output Leakage
Max
µs
2.3
V
0.7×VCC
VTH < 4.0V
VTH < 4.0V
10
/MR Glitch Immunity
V
0.8
20
100
0.25×VCC
30
V
V
kΩ
ns
Notes:
1. Exceeding the absolute maximum rating may damage the device.
2. The device is not guaranteed to function outside its operating rating.
3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
4. Various reset thresholds available. See ordering information or contact factory.
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MIC6315
Micrel
Timing Diagram
VCC
VTH
/MR
tRST
/RESET
tRST
Reset Timing Diagram
Functional Diagram
+
VCC (4)
Reset
Threshold (V)
RESET (2)
-
RESET
GENERATOR
MR (3)
GND (1)
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MIC6315
Micrel
Applications Information
Wire OR'ing The /RESET Output
Because the RESET output is open-drain, several reset
sources can be wire-ORed, in parallel, to allow resets from
multiple sources.
VCC Transients
The MIC6315 is relatively immune to negative-going VCC
glitches below the reset threshold. Typically, a negative-going
transient 125mV below the reset threshold with a duration of
20µs or less will not cause an unwanted reset. If additional
transient immunity is needed, a bypass capacitor can be
placed a close as possible to the MIC6315.
Microprocessor Reset
The /RESET pin is asserted whenever VCC falls below the
reset threshold voltage or if /MR (manual reset) is forced
low. The /RESET pin remains asserted for the duration of
the reset timeout period after VCC has risen above the reset
threshold or /MR has returned high. The reset function ensure the microprocessor is properly reset and powers up in
a known condition after a power failure. /RESET will remain
valid with VCC as low as 1V.
The /RESET output is a simple open-drain N-channel MOSFET structure. A pull-up resistor must be used to pull this
output up to some voltage. For most applications, this voltage will be the same power supply that supplies VCC to the
MIC6315. It is possible, however, to tie this resistor to some
other voltage. This will allow the MIC6315 to monitor one
voltage while level-shifting the /RESET output to some other
voltage. The pull-up voltage must be limited to 6.0V or less
(absolute maximum) to avoid damage to the MIC6315. The
resistor must be small enough to supply current to the inputs
and leakage paths that are driven by the /RESET output.
/RESET Valid at Low Voltage
As VCC drops to 0V, the MIC6315 will no longer be able to
pull the /RESET output low. At this point, the pull-up resistor
will pull the output high. The value of the pull-up resistor and
the voltage it is connected to will affect the point at which
this happens.
October 2005
+5.0V
+3.3V
VCC
VCC
MIC6315
MR
RESET
10k
5V SYSTEM
RESET
MIC6315 Used in a Multiple Supply System
5
M9999-102005
MIC6315
Micrel
Package Information
0.950 (0.0374) TYP
1.40 (0.055) 2.50 (0.098)
1.20 (0.047) 2.10 (0.083)
CL
CL
DIMENSIONS:
MM (INCH)
1.12 (0.044)
0.81 (0.032)
3.05 (0.120)
2.67 (0.105)
0.800 (0.031) TYP
0.400 (0.016) TYP 3 PLACES
8
0
0.10 (0.004)
0.013 (0.0005)
0.150 (0.0059)
0.089 (0.0035)
0.41 (0.016)
0.13 (0.005)
4-Pin SOT-143 (U)
MICREL, INC.
2180 FORTUNE DRIVE
SAN JOSE, CA 95131
USA
TEL + 1 (408) 944-0800 FAX + 1 (408) 474-1000 WEB http://www.micrel.com
The information furnished by Micrel in this datasheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use.
Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.
Micrel Products are not�
reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into
the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser’s
use or sale of Micrel Products for use in life support appliances, devices or systems is at Purchaser’s own risk and Purchaser agrees to fully indemnify
Micrel for any damages resulting from such use or sale.
© 2005 Micrel, Incorporated.
M9999-102005
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