Data Sheet
PT7M1818/1813 Supervisory Circuit
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Features
•
•
•
•
•
•
•
Highly accurate:
±1.5%
(25°C)
Accurate power monitoring: 2.5V, 2.9V, 3.0V
(PT7M1818), and 4.1, 4.3, 4.6V (PT7M1813)
Operating voltage range: 1.0V ~ 5.5V
Operating temperature range: -40°C to + 85°C
Detect voltage temperature characteristics:
±2.5% ×
TYP
Efficient operation output with internal 5kΩ pull-up
resistor
Maintains reset for 200ms after V
CC
returns to an in-
tolerance condition
General
The series are designed to monitor power supplies in µP
and digital systems. It provides excellent circuit
reliability and low cost by eliminating external
components and adjustments.
This device performs a single function: it asserts a reset
signal whenever the V
CC
supply voltage falls below a
preset threshold. Reset remains asserted for 200ms after
V
CC
has risen above the reset threshold.
PT7M1818/1813 are bidirectional output, allowing it to
be directly connected to µP with bidirectional reset inputs.
Ordering Information
Part Number
PT7M1818-20T
PT7M1818-20NBE
PT7M1818-10T
PT7M1818-10NBE
PT7M1818-5T
PT7M1818-5NBE
PT7M1813-15T
PT7M1813-15NBE
PT7M1813-10T
PT7M1813-10NBE
PT7M1813-5T
PT7M1813-5NBE
Package
SOT23-3
TO92 Lead free
SOT23-3
TO92 Lead free
SOT23-3
TO92 Lead free
SOT23-3
TO92 Lead free
SOT23-3
TO92 Lead free
SOT23-3
TO92 Lead free
Note:
Lead free package is available by adding “E” after each
part no. For example: PT7M
1818-20TE
is lead free package
part no for
PT7M1818-20T.
Table 1.
Function comparison
Reset Output
Item
1
2
3
4
5
6
Part No.
PT7M1818-20
PT7M1818-10
PT7M1818-5
PT7M1813-15
PT7M1813-10
PT7M1813-5
Open-Drain
Active high
Active low
-
-
-
-
-
-
-
-
-
-
-
-
Push-Pull
Active high
Active low
-
-
-
-
-
-
-
-
-
-
-
-
Bi-direct
Active low
√
√
√
√
√
√
V
TH-
(V)
2.5
2.9
3.0
4.1
4.3
4.6
PT0190(03/05)
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Ver: 1
Data Sheet
PT7M1818/1813 Supervisory Circuit
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Block Diagram
Vcc
Reset
Monitor
VCC Resistor
Divider
Timing
Delay
T.C.
Reference
5k
RST
GND
Pin Configuration
PT7M1818/1813
1
RST
PT7M1818/1813
GND
3
1
2
3
2
VCC
RST VCC GND
TO-92
SOT23-3
Pin Description
Name Type
Description
Reset Output and Pushbutton Input:
RST is asserted when V
CC
drops below voltage threshold
V
TH-
. Active low. When other devices pull RST low, the reset condition occurs and will remain a
reset timeout period after the external signal is off.
Ground
Supply Voltage.
RST
I/O
GND
V
CC
P
P
PT0190(03/05)
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Ver: 1
Data Sheet
PT7M1818/1813 Supervisory Circuit
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Function Description
Power Monitor
A microprocessor’s (µP’s) reset input starts the µP in a known state. Whenever the µP is in an unknown state, it should be held in
reset. The supervisory circuits assert reset during power-up and prevent code execution errors during power-down or brownout
conditions.
On power-up, once Vcc reaches about 1.0V, RST is a guaranteed logic low of 0.4V or less. As Vcc rises, RST stays low. When
Vcc rises above the reset threshold V
RST
, an internal timer releases RST after about 200ms. RST asserts whenever Vcc drops
below the reset threshold, i.e. brownout condition. If brownout occurs in the middle of a previously initiated reset pulse, the pulse
continues for at least another 200ms. On power-down, once Vcc falls below the reset threshold, RST stays low and is guaranteed
to be 0.4V or less until Vcc drops below 1V.
Reset Output: Bi-direction
The devices provide RST output pin for a pushbutton switch. When the devices are not in a reset cycle, it continuously monitors
the RST signal for a low going edge. If an edge is detected, the devices will debounce the switch by pulling the RST line low.
After the internal timer has expired, the devices will continue to monitor the RST line. If the line is still low, they will continue to
monitor the line looking for a rising edge. Upon detecting a release, they will force the RST line low and hold it low for 200ms.
Application Information
Typical Operation Circuit
Vcc
PT7M1818
PT7M70xxBL
/1813
PT7M71xxBL
RST
MICROPROCESSOR
RESET
PT0190(03/05)
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Ver: 1
Data Sheet
PT7M1818/1813 Supervisory Circuit
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Maximum Ratings
Storage Temperature ............................................................-65
o
C to +150
o
C
Ambient Temperature with Power Applied.......................... -40
o
C to +85
o
C
Supply Voltage to Ground Potential (Vcc to GND) ..............-0.3V to +7.0V
DC Input Voltage (All inputs except Vcc and GND)......-0.3V to V
CC
+0.3V
DC Output Current (All outputs) ..........................................................30mA
Power Dissipation .......................................... 320mW (Depend on package)
Note:
Stresses greater than those listed under MAXIMUM
RATINGS may cause permanent damage to the
device. This is a stress rating only and functional
operation of the device at these or any other
conditions above those indicated in the operational
sections of this specification is not implied. Exposure
to absolute maximum rating conditions for extended
periods may affect reliability.
DC Electrical Characteristics
(T
A
= -40~85ºC, unless otherwise noted. Typical values are at T
A
= +25ºC)
Description
Supply Voltage
Supply Current
Sym.
V
CC
V
CC
= 5.5V. No load.
I
CC
V
CC
= 3.6V. No load.
+25°C
Voltage Threshold
V
TH-
-40°C~85°C
Hysteresis
V
HYS
V
TH+
- V
TH-*
I
OH
= 8mA, V
CC
= 5V
Output
Driving
Output low
V
OL
I
OH
= 4mA, V
CC
= 3V
I
OH
= -50µA, V
CC
= 1V
Internal pull-up resistor
Rp
(V
TH-
)
×0.985
(V
TH-
)
×0.975
V
TH-
V
TH-
50
0.4
0.3
0.09
V
10
(V
TH-
)
×1.015
(V
TH-
)
×1.025
µA
V
Test Conditions
Min
1.0
Typ
Max
5.5
12
Unit
V
µA
mV
3.75
5
6.25
kΩ
RST
Note:
V
TH-
is voltage threshold when V
CC
falls from high to low. V
TH+
is voltage threshold when V
CC
rises from low to high.
PT0190(03/05)
4
Ver: 1
Data Sheet
PT7M1818/1813 Supervisory Circuit
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AC Electrical Characteristics
Fig 7. Timing diagram
t
SEN
VCC
V
RST
1V
0V
t
RS
t
RPD
t
RS
RST
1V
0V
Uncertain state
Fig 8. Timing diagram
V
RST
VCC
1V
0V
t
RS
t
PD
t
RS
RST
0.8V
CC
1V
0.8V
0V
Uncertain state
External pull down
signal release
(V
CC
= 1.0V to 5.5V, T
A
= -40~85ºC, unless otherwise noted. Typical values are at T
A
= +25ºC)
Sym.
t
RS
t
RPD
t
SEN
t
PD
Description
Reset Timeout Period
Delay
Sensitivity
External Pull Down Signal Pulse
Pushbutton Detect
*
RST pin
20
1
0.8
1.5
2.0
Test Conditions
Min
140
Typ
200
17
Max
280
Unit
ms
µs
µs
µs
V
RST pin
*Note: RST will be asserted when it is pull down to the typical value or less.
PT0190(03/05)
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Ver: 1
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