MAX6343ZUT-T [MAXIM]
Analog IC ; 模拟IC\n
| 型号： | MAX6343ZUT-T |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Analog IC
|
| 文件： | 总8页 (文件大小：238K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-1568; Rev 1; 3/00
6-Pin µP Reset Circuit with
Power-Fail Comparator
General Description
Features
The MAX6342–MAX6345 family of microprocessor (µP)
supervisory circuits monitors power supplies in digital sys-
tems. These devices significantly improve system reliabili-
ty and accuracy compared to separate ICs or discrete
components.
o Small 6-Pin SOT23 Package
o Precision Factory-Set V Reset Thresholds
CC
Between 2.33V and 4.63V
o Guaranteed RESET Valid to V
= +1V
CC
The MAX6342–MAX6345 provide factory-trimmed V
CC
o 100ms min Reset Pulse Width
reset threshold voltages from 2.33V to 4.63V and operate
with supply voltages between +1V and +5.5V. A +1.25V
threshold detector allows for a power-fail warning, for
low-battery detection, or for monitoring another power
supply. The MAX6342 contains an MR input and an
active-low push-pull reset. The MAX6343 and MAX6344
are identical to the MAX6342 except they provide an
active-low, open-drain reset and an active-high, push-
pull reset, respectively. The MAX6345 provides a second
reset output in place of the MR input to give it an active-
high push-pull reset and an active-low push-pull reset.
o Debounced CMOS-Compatible Manual-Reset
Input
o Voltage Monitor for Power-Fail or Low-Battery
Warning
Ordering Information
PART
TEMP. RANGE
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
PIN-PACKAGE
6 SOT23-6
6 SOT23-6
6 SOT23-6
6 SOT23-6
MAX6342_UT-T
MAX6343_UT-T
MAX6344_UT-T
MAX6345_UT-T
All of the devices are packaged in a miniature 6-pin
SOT23.
Note: The MAX6342–MAX6345 are available with factory-set
reset thresholds from 2.33V to 4.63V (see Selector Guides 1, 2).
Insert the letter corresponding to the desired nominal reset
threshold into the blank following the part number. There is a
2500 piece order increment required for the SOT package. SOT
Top Marks table appears at end of data sheet.
Applications
Portable Computers
Telecom Equipment
Networking Equipment
Portable/Battery-Powered Equipment
Multivoltage Systems
Pin Configurations
Embedded Control Systems
TOP VIEW
Typical Operating Circuit appears at end of data sheet.
V
1
2
3
6
5
4
RESET (RESET)
CC
Selector Guide 1
RESET THRESHOLD (V)
MAX6342
MAX6343
MAX6344
SUFFIX
GND
PFI
MR
4.63
4.38
3.08
2.93
2.63
2.33
L
M
T
PFO
S
R
Z
( ) ARE FOR MAX6344 ONLY.
SOT23-6
Pin Configurations continued at end of data sheet.
Selector Guide 2
PUSH-PULL
RESET OUTPUT
OPEN-DRAIN
RESET OUTPUT
PUSH-PULL RESET
OUTPUT
MANUAL-RESET
INPUT
PART
✔
✔
✔
✔
—
MAX6342
MAX6343
MAX6344
MAX6345
—
—
—
✔
✔
✔
—
—
✔
—
—
________________________________________________________________ Maxim Integrated Products
1
For free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
6-Pin µP Reset Circuit with
Power-Fail Comparator
ABSOLUTE MAXIMUM RATINGS
V
CC
to GND..............................................................-0.3V to +6V
Continuous Power Dissipation (T = +70°C)
A
RESET, RESET
6-Pin SOT23 (derate 4mW/°C above +70°C).............320mW
Operating Temperature Range .........................-40°C to +125°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature Range (soldering, 10s)..................... +300°C
(MAX6342/MAX6344/MAX6345) ......... -0.3V to (V
RESET (MAX6343)................................................... -0.3V to +6V
MR, PFI, PFO..............................................-0.3V to (V + 0.3V)
+ 0.3V)
CC
CC
Input Current, V ..............................................................50mA
CC
Output Current, RESET, RESET ..........................................50mA
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(V
= +1.0V to +5.5V, T = -40°C to +125°C, unless otherwise noted. Typical values are at T = +25°C and V
= +3V.) (Note 1)
CC
A
A
CC
PARAMETER
SYMBOL
CONDITIONS
MIN
1.0
TYP
MAX
UNITS
T
T
= 0°C to +70°C
5.5
A
Supply Voltage Range
Supply Current
V
CC
V
= -40°C to +125°C
1.2
5.5
40
A
V
CC
V
CC
V
CC
V
CC
= 3V, TA = -40° to +85°C
= 5.5V, TA = -40° to +85°C
= 3V, TA = -40° to +125°C
= 5.5V, TA = -40° to +125°C
25
30
50
I
No load
µA
CC
25
50
30
60
T
T
T
= +25°C
4.56
4.50
4.40
4.31
4.25
4.16
3.03
3.00
2.92
2.89
2.85
2.78
2.59
2.55
2.50
2.30
2.25
2.21
4.63
4.70
4.75
4.86
4.45
4.50
4.56
3.13
3.15
3.23
2.97
3.00
3.08
2.67
2.70
2.76
2.36
2.38
2.45
A
A
A
MAX634_L
MAX634_M
MAX634_T
MAX634_S
MAX634_R
MAX634_Z
= -40°C to +85°C
= -40°C to +125°C
= +25°C
T
4.38
3.08
2.93
2.63
2.33
20
A
A
A
T
T
= -40°C to +85°C
= -40°C to +125°C
= +25°C
T
A
A
A
T
T
= -40°C to +85°C
= -40°C to +125°C
= +25°C
Reset Threshold
V
V
TH
T
A
A
A
A
A
A
T
T
T
T
T
= -40°C to +85°C
= -40°C to +125°C
= +25°C
= -40°C to +85°C
= -40°C to +125°C
= +25°C
T
A
A
A
T
T
= -40°C to +85°C
= -40°C to +125°C
V
CC
to Reset Delay
V
CC
V
CC
V
CC
V
CC
V
CC
V
CC
= V to (V - 100mV)
µs
V
TH
TH
> 1.2V, I
> 2.7V, I
> 4.5V, I
> 1.2V, I
= 100µA
0.4
0.3
0.4
SINK
SINK
SINK
V
OL
= 1.2mA
= 3.2mA
RESET and RESET
Outputs Drive
Capability (Note 2)
= 50µA
0.8 ✕ VCC
0.8 ✕ VCC
SOURCE
> 2.7V, I
= 500µA
SOURCE
(MAX6342/MAX6345 only)
V
OH
V
V
> 4.5V, I = 800µA
CC
SOURCE
0.8 ✕ VCC
(MAX6342/MAX6345 only)
2
_______________________________________________________________________________________
6-Pin µP Reset Circuit with
Power-Fail Comparator
ELECTRICAL CHARACTERISTICS (continued)
(V
= +1.0V to +5.5V, T = -40°C to +125°C, unless otherwise noted. Typical values are at T = +25°C and V
= +3V.) (Note 1)
CC
A
A
CC
PARAMETER
Reset Timeout Period
SYMBOL
CONDITIONS
= -40°C to +85°C
MIN
100
80
TYP
MAX
280
UNITS
T
T
180
A
t
RP
ms
= -40°C to +125°C
360
A
Open-Drain RESET Output
Leakage Current (Note 3)
I
MAX6343 only, V
> V
1
µA
LKG
CC
TH(MAX)
V
V
V
MR Input Low
0.3 ✕ VCC
IL
V
IH
MR Input High
0.7 ✕ VCC
60
1
kΩ
µs
µs
µs
MR Pull-Up Resistance
MR Minimum Pulse Width
MR Glitch Rejection
MR to Reset Delay
0.1
0.2
T
T
T
T
= -40°C to +85°C
1.2
1.25
1.3
1.35
25
A
A
A
A
PFI Input Threshold
V
= -40°C to +125°C
= -40°C to +85°C
= -85°C to +125°C
1.15
0.01
PFI Leakage Current (Note 3)
nA
100
0.4
V
V
= 4.5V, I
= 4.5V, I
= 3.2mA
V
V
PFO Output Voltage
PFO Output Voltage
OL
CC
CC
SINK
V
OH
V
= 800µA
0.8 ✕ VCC
SOURCE
Output sink current
20
5
PFO Output Short-Circuit
Current
mA
µs
Output source current
V
= 15mV
3
PFI to PFO Delay
OVERDRIVE
Note 1: Overtemperature limits are guaranteed by design and not production tested.
Note 2: Apply to each part in accordance with threshold voltage, output configuration, and manual reset status selected.
Note 3: Leakage parameters are guaranteed by design and not production tested.
Typical Operating Characteristics
(V
= V = +5V, T = +25°C, unless otherwise noted.)
CC A
PFI
MAX6344L/MAX6345L
RESET OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
MAX6342M/MAX6345M
RESET OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
SUPPLY CURRENT vs. SUPPLY VOLTAGE
AND TEMPERATURE
30
V
CC
= 5V
V
CC
25
20
15
10
5
V
CC
V
CC
= 3.3V
V
CC
= 2.5V
1V/div
1V/div
RESET
0
0
V
CC
= 1V
0
0
RESET
0
1sec/div
1sec/div
-40
-15
10
35
60
85
TEMPERATURE (°C)
_______________________________________________________________________________________
3
6-Pin µP Reset Circuit with
Power-Fail Comparator
Typical Operating Characteristics (continued)
(V
= V = +5V, T = +25°C, unless otherwise noted.)
CC A
PFI
PFO OUTPUT VOLTAGE HIGH
vs. SUPPLY VOLTAGE
PFO OUTPUT VOLTAGE LOW
vs. SUPPLY VOLTAGE
6
5
4
3
2
1
0
0.60
0.55
0.50
0.45
0.40
0.35
0.30
0.25
0.20
R = 10kΩ
R = 1kΩ
L
L
0
1
2
3
4
5
6
0
1
2
3
4
5
6
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
MAX6342/MAX6345
RESET RESPONSE TIME
MAX6344/MAX6345
RESET RESPONSE TIME
5V
5V
V
CC
4V
V
CC
4V
5V
RESET
4V
4V
RESET
0
0
2µs/div
10µs/div
Pin Description
PIN
NAME
FUNCTION
MAX6342
MAX6343
MAX6344
MAX6345
1
2
1
2
1
2
1
2
V
Supply Voltage
Ground
CC
GND
PFI
Power-Fail Voltage Monitor Input. When PFI is <1.25V, PFO
goes low. Connect PFI to GND or V
3
4
3
4
3
4
3
4
when not used.
CC
Power-Fail Voltage Monitor Output
PFO
4
_______________________________________________________________________________________
6-Pin µP Reset Circuit with
Power-Fail Comparator
Pin Description (continued)
PIN
NAME
FUNCTION
MAX6342
MAX6343
MAX6344
MAX6345
Manual-Reset Input. Pull low to force a reset. RESET or RESET
remains active as long as MR is low and for the reset timeout
period after MR goes high. Leave unconnected or connect to
5
5
5
—
MR
V
CC
if unused.
Active-Low Reset Output. Push-pull for MAX6342/MAX6345.
Open-drain for MAX6343. It remains low for 180ms after V
rises above the reset threshold or MR goes from low to high.
6
6
—
6
5
6
RESET
CC
Active-High Push-Pull Reset Output. It remains high for 180ms
—
—
RESET
after V
rises above the reset threshold or MR goes from low
CC
to high.
V
CC
1
V
1
CC
RESET
6
6
RESET
GENERATOR
RESET
GENERATOR
RESET
(RESET)
V
CC
V
TH
V
TH
100k
MAX6342
MAX6343
MAX6344
5
4
2
3
RESET
PFO
5
4
2
3
MAX6345
MR
GND
PFI
GND
PFI
PFO
1.25V
1.25V
( ) ARE FOR MAX6344 ONLY.
Figure 1. MAX6342/MAX6343/MAX6344 Functional Diagram
Figure 2. MAX6345 Functional Diagram
Connect a pull-up resistor from RESET to any positive
supply voltage up to +5.5V (Figure 3). Select a resistor
value large enough to register a logic low (see Elec-
trical Characteristics), and small enough to register a
logic high while supplying all input current and leakage
paths connected to the RESET line. A 10kΩ pull-up is
sufficient in most applications.
_______________Detailed Description
Reset Output
A µP’s reset input starts the µP in a known state. These
µP supervisory circuits assert reset to prevent code-
execution errors during power-up, power-down, or
brownout conditions.
RESET and RESET are guaranteed to be asserted at a
Manual Reset
The MAX6342/MAX6343/MAX6344s’ manual-reset input
(MR) allows reset to be triggered by a pushbutton
switch. The switch is effectively debounced by the 1µs
min reset pulse width. MR is CMOS-logic compatible.
valid logic level for V
> +1V (see Electrical Char-
CC
acteristics). Once RESET asserts, it remains asserted
for at least 100ms (t ) after V
rises above its thresh-
CC
RP
old value or after MR returns high (Figures 1 and 2).
Open-Drain RESET Output
The MAX6343 has an active-low, open-drain reset out-
put. This output sinks current when RESET is asserted.
Power-Fail Comparator
The power-fail comparator is useful for various purpos-
es because the power-fail output (PFO) is independent
_______________________________________________________________________________________
5
6-Pin µP Reset Circuit with
Power-Fail Comparator
160
+5.0V
+3.3V
140
120
100
V
CC
10k
V
CC
µP
RESET
RESET
80
60
MAX634_L/M
MAX6343
40
20
0
MAX634_T/S/R/Z
GND
1
10
100
1000
RESET COMPARATOR OVERDRIVE, V - V (mV)
TH
CC
Figure 4. Maximum Transient Duration Magnitude Rejection
Figure 3. Open-Drain RESET Output Allows Use with Multiple
Supplies
V
CC
V
CC
100k
V
CC
V
RESET
MAX6342
MAX6345
CC
GND
RESET
GND
MAX6344
MAX6345
100k
Figure 5. Ensuring RESET Valid to V
Push-Pull Outputs
= 0 on Active-Low
Figure 6. Ensuring RESET Valid to V
Push-Pull Outputs
= 0 on Active-High
CC
CC
of the reset output. The inverting input is internally con-
nected to a +1.25V reference.
negative-going V
transient can have without causing
CC
a reset pulse. As the magnitude of the transient increas-
es (goes further below the reset threshold), the maxi-
mum allowable pulse width decreases.
To build an early-warning circuit for power failure, con-
nect the PFI pin to a voltage divider (see Typical Oper-
ating Circuit). Choose the voltage-divider ratio so that
the voltage at PFI falls below +1.25V just before the
+5V regulator drops out. Use PFO to interrupt the µP to
prepare for an orderly shutdown.
Typically, a V
transient that goes 100mV below the
CC
reset threshold and lasts 12µs or less will not cause a
reset pulse. A 1µF bypass capacitor mounted as close
as possible to the V
immunity.
pin provides additional transient
CC
__________Applications Information
Ensuring a Valid Reset Output
Down to V = 0
Negative-Going V
Transients
The MAX6342–MAX6345 supervisors are immune to
CC
CC
The MAX6342–MAX6345 are guaranteed to operate
properly down to V = +1V. In applications that require
short-duration, negative-going V
transients (glitches)
CC
CC
that usually do not require the entire system to shut down.
valid reset levels down to V
= 0, a pull-down resistor
CC
Figure 4 shows typical transient duration vs. reset com-
parator overdrive, for which the MAX6342–MAX6345 do
not generate a reset pulse. The graph was generated
to active-low outputs (MAX6342/MAX6345) and a pull-up
resistor to active-high outputs (MAX6344/MAX6345)
ensure that the reset line is valid when the reset output is
no longer sinking or sourcing current (Figures 5 and 6).
Note that this method does not work with the open-drain
output of the MAX6343. The resistor value used is not
critical, but it must be large enough not to load the reset
using a negative-going pulse applied to V , starting
CC
0.5V above the actual reset threshold and ending below
it by the magnitude indicated (reset comparator over-
drive). The graph indicates the maximum pulse width a
6
_______________________________________________________________________________________
6-Pin µP Reset Circuit with
Power-Fail Comparator
V
CC
BUFFERED RESET TO
OTHER SYSTEM
COMPONENTS
V+
RESET
TO µP
V
R1
R2
CC
(RESET)
MAX6342
MAX6343
MAX6344
V
CC
V
CC
PFI
MR
MAX6342
MAX6345
µP
PFO
4.7k
GND
RESET
RESET
( ) ARE FOR MAX6344 ONLY.
GND
GND
Figure 7. Monitoring Two Supplies
V
CC
Figure 9. Interfacing to µPs with Bidirectional Reset I/O
resistors and transistor as shown, a high PFO triggers
reset. As long as PFO remains high, the MAX6342/
MAX6343/MAX6344 will keep reset asserted. Note that
the accuracy of this circuit depends on the PFI thresh-
R1
100k
V
CC
MR
100k
MAX6342
MAX6343
MAX6344
old tolerance, the V
line voltage, and the resistors.
CC
PFO
PFI
Also, ensure that the voltage at PFI remains above
GND.
R2
RESET
(RESET)
Interfacing to µPs with
Bidirectional Reset Pins
Use the circuit shown in Figure 9 to interface the
MAX6342 or MAX6345 with a µP with bidirectional reset
pins. The 4.7kΩ resistor between the reset output and
the µP I/O line will ensure that the resets do not cause
an indeterminate logic level.
GND
V-
V
- 1.25V = 1.25V - V
TRIP
CC
R1
R2
V
TRIP
< 0
( ) ARE FOR MAX6344 ONLY.
Figure 8. Monitoring a Negative Voltage
output when V
is above the reset threshold. For most
CC
applications, 100kΩ is adequate.
SOT Top Marks
Monitoring Two Supplies
SOT TOP
MARK
SOT TOP
MARK
PART
PART
Monitor another voltage by connecting a resistor-divider
to PFI as shown in Figure 7. The threshold voltage will
then be given by:
MAX6342LUT-T
MAX6342MUT-T
MAX6342TUT-T
MAX6342SUT-T
MAX6342RUT-T
MAX6342ZUT-T
MAX6343LUT-T
MAX6343MUT-T
MAX6343TUT-T
MAX6343SUT-T
MAX6343RUT-T
MAX6343ZUT-T
AACP
AACQ
AACR
AACS
AACT
AACU
AACV
AACW
AACX
AACY
AACZ
AADA
MAX6344LUT-T
MAX6344MUT-T
MAX6344TUT-T
MAX6344SUT-T
MAX6344RUT-T
MAX6344ZUT-T
MAX6345LUT-T
MAX6345MUT-T
MAX6345TUT-T
MAX6345SUT-T
MAX6345RUT-T
MAX6345ZUT-T
AADQ
AADR
AADS
AADT
AADU
AADV
AADW
AADX
AADY
AADZ
AAEA
AAEB
V
= 1.25[(R1 + R2) / R2]
TH(PFI)
where V
is the threshold at which the monitored
TH(PFI)
voltage will trip PFO.
A good rule of thumb for selecting the resistors is to
choose R2 between 250kΩ and 500kΩ and solve for R1.
Connect PFO to MR in applications that require reset to
assert when the second voltage falls below its threshold.
Monitoring a Negative Voltage
Connect the circuit as shown in Figure 8 to use the
power-fail comparator to monitor a negative supply rail.
PFO stays low when V- is good. When V- rises to cause
PFI to be above +1.25V, PFO goes high. By adding the
_______________________________________________________________________________________
7
6-Pin µP Reset Circuit with
Power-Fail Comparator
Typical Operating Circuit
Pin Configurations (continued)
UNREGULATED DC
TOP VIEW
LINEAR
REGULATOR
V
1
2
3
6
5
4
RESET
RESET
CC
MAX6345
GND
PFI
V
CC
V
CC
PFI
MR
RESET
µP
RESET
PFO
MAX6342
PFO
INTERRUPT
SOT23-6
PUSHBUTTON
SWITCH
Chip Information
TRANSISTOR COUNT: 403
________________________________________________________Package Information
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2000 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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