MIC6315
Micrel
MIC6315
Open-Drain µP Reset Circuit
General Description
The MIC6315 is an inexpensive reset generator circuit that
monitors power supplies in microprocessor based sys-
tems.
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 V
CC
has
risen above the designed reset threshold level. The MIC6315
comes in a 4-pin SOT-143 package.
Features
• Precision voltage monitor for 3V, 3.3V or 5V power sup-
plies
• /RESET remains valid with V
CC
as low as 1V
• 5µA supply current
• 20ms, 140ms, or 1100ms minimum reset pulse widths
available
• Manual reset input
• 4-pin SOT-143 package
Applications
•
•
•
•
•
Portable equipment
Intelligent instruments
Critical microprocessor power monitoring
Printers/computers
Embedded controllers
Typical Application
VCC
VCC
VCC
10k
MIC6315
MR
RESET
µP
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
September 2008
1
M9999-091608
MIC6315
Micrel
Pb-Free
Part Number
Nominal
V
TH
(V)
2.63
2.93
3.00
3.08
4.00
4.10
4.38
4.63
2.63
2.93
3.00
3.08
4.00
4.10
4.20
4.38
4.63
2.63
2.93
3.00
3.08
4.00
4.10
4.38
4.63
Min. t
RST
(ms)
20
20
20
20
20
20
20
20
140
140
140
140
140
140
140
140
140
1100
1100
1100
1100
1100
1100
1100
1100
Operating
Temp. Range
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
Ordering Information
(1, 2)
Standard
Part Number
Marking
NY
NM
N2
NF
NW
N6
NG
NQ
NR
NP
N3
NU
N8
N5
0N
NH
NX
NS
NN
N4
2N
M9
M7
NJ
NZ
MIC6315-26D2U
MIC6315-29D2U
MIC6315-30D2U
MIC6315-31D2U
MIC6315-40D2U
MIC6315-41D2U
MIC6315-44D2U
MIC6315-46D2U
MIC6315-26D3U
MIC6315-29D3U
MIC6315-30D3U
MIC6315-31D3U
MIC6315-40D3U
MIC6315-41D3U
MIC6315-42D3U
MIC6315-44D3U
MIC6315-46D3U
MIC6315-26D4U
MIC6315-29D4U
MIC6315-30D4U
MIC6315-31D4U
MIC6315-40D4U
MIC6315-41D4U
MIC6315-44D4U
MIC6315-46D4U
Notes:
Marking
NY
NM
N2
NF
NW
N6
NG
NQ
NR
NP
N3
NU
N8
N5
0N
NH
NX
NS
NN
N4
2N
M9
M7
NJ
NZ
Package
4-lead SOT-143
4-lead SOT-143
4-lead SOT-143
4-lead SOT-143
4-lead SOT-143
4-lead SOT-143
4-lead SOT-143
4-lead SOT-143
4-lead SOT-143
4-lead SOT-143
4-lead SOT-143
4-lead SOT-143
4-lead SOT-143
4-lead SOT-143
4-lead SOT-143
4-lead SOT-143
4-lead SOT-143
4-lead SOT-143
4-lead SOT-143
4-lead SOT-143
4-lead SOT-143
4-lead SOT-143
4-lead SOT-143
4-lead SOT-143
4-lead SOT-143
MIC6315-26D2UY
MIC6315-29D2UY
MIC6315-30D2UY
MIC6315-31D2UY
MIC6315-40D2UY
MIC6315-41D2UY
MIC6315-44D2UY
MIC6315-46D2UY
MIC6315-26D3UY
MIC6315-29D3UY
MIC6315-30D3UY
MIC6315-31D3UY
MIC6315-40D3UY
MIC6315-41D3UY
MIC6315-42D3UY
MIC6315-44D3UY
MIC6315-46D3UY
MIC6315-26D4UY
MIC6315-29D4UY
MIC6315-30D4UY
MIC6315-31D4UY
MIC6315-40D4UY
MIC6315-41D4UY
MIC6315-44D4UY
MIC6315-46D4UY
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 V
CC
MIC6315
RESET 2
3 MR
MIC6315-xxDyU 4-Lead SOT-143
Pin Description
Pin Number
1
2
3
Pin Name
GND
/RESET
/MR
Pin Function
IC Ground Pin.
/RESET goes low if V
CC
falls below the reset threshold and remains asserted
for one reset timeout period after V
CC
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.
4
VCC
M9999-091608
2
September 2008
MIC6315
Micrel
Absolute Maximum Ratings
(1)
Terminal Voltage
(V
CC
, /RESET) ........................................–0.3V to 6.0V
(/MR) ..........................................–0.3V to (V
CC
+ 0.3V)
Rate of Rise (V
CC
) ..................................................
100V/µs
Input Current (V
CC
, /MR) ............................................
20mA
Output Current (/RESET) ...........................................
20mA
Lead Temperature (soldering, 10 sec.) ...................... 300°C
Storage Temperature (T
S
) ......................... –65°C to 150°C
ESD Rating(3) ............................................................... 3kV
Operating Ratings
(2)
Operating Temperature Range ................... –40°C to +85°C
Input Voltage (/RESET) .................................... GND – 5.5V
Power Dissipation (T
A
= +70°C) .............................. 320mW
Electrical Characteristics
For typical values, V
CC
= 2.5V to 5.5V, T
A
= 25°C;
bold
values indicate –40°C ≤ T
A
≤ +85°C; unless noted
Symbol
V
CC
I
CC
Parameter
Condition
Min
1
V
CC
= 5.5V, no load
Note 4
D2U
D3U
D4U
V
OL
/RESET Output Voltage
V
CC
> 2.5V, I
SINK
= 1.2mA
/RESET Output Leakage
V
IH
V
IL
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.
Typ
5
5
Max
5.5
15
10
V
TH
+2.5%
44
320
2500
0.4
0.3
0.3
1
Units
V
µA
µA
V
ms
ms
ms
V
V
V
µA
µs
µs
V
V
Operating Voltage Range
Supply Current
Reset Voltage Threshold
Reset Timeout Period
V
CC
= 3.6V, no load
t
RST
V
TH
V
TH
–2.5%
20
140
1100
10
2.3
0.7×V
CC
V
TH
28
200
1500
0.5
V
CC
≥ 4.0V, I
SINK
= 3.2mA
/RESET deasserted
V
TH
> 4.0V
V
TH
< 4.0V
V
TH
< 4.0V
V
TH
> 4.0V
V
CC
≥ 1.0V, I
SINK
= 50µA
/MR Minimum Pulse Width
/MR to Reset Delay
/MR Input Threshold
/MR Input Threshold
/MR Pull-Up Resistance
/MR Glitch Immunity
0.8
20
100
0.25×V
CC
30
V
V
kΩ
ns
10
September 2008
3
M9999-091608
MIC6315
Micrel
Timing Diagram
V
CC
/MR
V
TH
/RESET
t
RST
t
RST
Reset Timing Diagram
Functional Diagram
VCC (4)
Reset
Threshold (V)
MR (3)
+
-
RESET
GENERATOR
RESET (2)
GND (1)
M9999-091608
4
September 2008
MIC6315
Micrel
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.
V
CC
Transients
The MIC6315 is relatively immune to negative-going V
CC
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.
+3.3V
VCC
+5.0V
VCC
10k
Applications Information
Microprocessor Reset
The /RESET pin is asserted whenever V
CC
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 V
CC
has risen above the reset
threshold or /MR has returned high. The reset function en-
sure the microprocessor is properly reset and powers up in
a known condition after a power failure. /RESET will remain
valid with V
CC
as low as 1V.
The /RESET output is a simple open-drain N-channel MOS-
FET structure. A pull-up resistor must be used to pull this
output up to some voltage. For most applications, this volt-
age will be the same power supply that supplies V
CC
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 V
CC
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.
MIC6315
MR
RESET
5V SYSTEM
RESET
MIC6315 Used in a Multiple Supply System
September 2008
5
M9999-091608
MCU
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