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PT7M1818/1813
Supervisory Circuit
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° to + 85°
C
C
Detect voltage temperature characteristics:
2.5%
TYP
Efficient open-drain output with internal 5k pull-up
resistor
Maintains reset for 200ms after V
CC
returns to an in-
tolerance condition
Description
The series are designed to monitor power supplies in µ
P
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 µ with bidirectional reset
P
inputs.
Pin Configuration
PT7M1818/1813
1
RST
GND
3
2
VCC
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
GND
V
CC
I/O
P
P
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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
= -40~85º unless otherwise noted. Typical values are at T
A
= +25º
C,
C)
Description
Supply Voltage
Supply Current
Sym.
V
CC
V
CC
= 5.5V. No load.
I
CC
V
CC
= 3.6V. No load.
+25C
Voltage Threshold
V
TH-
-40C~85C
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
= -50µ V
CC
= 1V
A,
Internal pull-up resistor
Rp
-
(V
TH-
)
0.985
(V
TH-
)
0.975
-
-
-
-
-
V
TH-
V
TH-
50
-
-
-
10
(V
TH-
)
1.015
(V
TH-
)
1.025
-
0.4
0.3
0.09
V
µA
V
V
mV
Test Conditions
Min
1.0
-
Typ
-
-
Max
5.5
12
Unit
V
µA
3.75
5
6.25
k
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.
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Supervisory Circuit
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AC Electrical Characteristics
Fig 1. Timing diagram
t
SEN
VCC
V
RST
1V
0V
t
RS
t
RPD
t
RS
RST
1V
0V
Uncertain state
Fig 2. 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
= -40~85º unless otherwise noted. Typical values are at T
A
= +25º
C,
C)
Sym.
t
RS
t
RPD
t
SEN
t
PD
Description
Reset Timeout Period
Delay
Sensitivity
External Pull Down Signal Pulse
Pushbutton Detect
*
-
-
-
RST pin
Test Conditions
Min
140
-
20
1
0.8
Typ
200
17
-
-
1.5
Max
280
-
-
-
2.0
Unit
ms
s
s
s
V
RST pin
*Note: RST will be asserted when it is pull down to the typical value or less.
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Supervisory Circuit
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Block Diagram
Vcc
Reset
Monitor
VCC Resistor
Divider
Timing
Delay
T.C.
Reference
5k
RST
GND
Function Description
Power Monitor
A microprocessor’s (µP’s) reset input starts the µP in a known state. Whenever the µ is in an unknown state, it should be held in
P
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
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Supervisory Circuit
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Mechanical Information
SOT23-3
DOCUMENT CONTROL NO.
PD-0018
REVISION: A
DATE: 5/17/2011
PKG. DIMENSIONS(MM)
SYMBOL
MIN
MAX
A
1.05
1.25
A1
0.00
0.10
A2
1.05
1.15
b
0.30
0.50
c
0.10
0.20
D
2.82
3.02
E
1.50
1.70
E1
2.65
2.95
e
0.95BSC
e1
1.80
2.00
L
0.30
0.60
θ
0°
8°
Pericom Technology (Shanghai) Co.Ltd.
3/F., 20 Building ,481 Gui Ping Road,
Shanghai,200233
Tel:(86-21)6485-0576. Fax: (86-21)6485-2181
Note:
1) Controlling dimensions in millimeters.
DESCRIPTION: 3-Pin Small Outline Transistor, Plastic
Package, SOT-23
PACKAGE CODE: TA3
Ordering Information
Part Number
PT7M1818-20TE
PT7M1818-10TE
PT7M1818-5TE
PT7M1813-15TE
PT7M1813-10TE
PT7M1813-5TE
Note:
E = Pb-free or Pb-free and Green
Adding X Suffix= Tape/Reel
Contact Pericom for availability.
Package Code
T
T
T
T
T
T
Package
Lead free and Green SOT23-3
Lead free and Green SOT23-3
Lead free and Green SOT23-3
Lead free and Green SOT23-3
Lead free and Green SOT23-3
Lead free and Green SOT23-3
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嵌入式系统
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