MAX6844FUKD4-T [MAXIM]
Power Management Circuit, Fixed, +1.05VV, BICMOS, PDSO5;
| 型号： | MAX6844FUKD4-T |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Power Management Circuit, Fixed, +1.05VV, BICMOS, PDSO5 信息通信管理 光电二极管 |
| 文件： | 总9页 (文件大小：211K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-2625; Rev 0; 10/02
Ultra-Low-Voltage µP Reset Circuits and
Voltage Detectors
General Description
Features
The MAX6841–MAX6845 microprocessor (µP) supervi-
sory circuits monitor ultra-low-voltage power supplies in
µP and digital systems. They provide excellent circuit
reliability at low cost by eliminating external compo-
nents and adjustments when used with +0.9V to +1.5V
systems. Factory-trimmed reset thresholds are avail-
able for the MAX6841/MAX6842. The MAX6843/
MAX6844/MAX6845 provide a RESET IN input, allowing
the user to externally adjust the reset threshold. The
MAX6841–MAX6845 family features a debounced man-
ual reset input (MR). The reset comparator is designed
o Factory-Set Reset Threshold Voltages for
Monitoring Supplies from 0.9V to 1.5V
(MAX6841/MAX6842)
o Adjustable Threshold RESET IN
(MAX6843/MAX6844/MAX6845)
o Low Power Consumption: 5.7µA (typ)
o
2.5ꢀ Reset Threshold Accuracy
Over Temperature
o Five Timeout Periods: 150µs (Voltage Detector
Version), 1.5ms, 30ms, 210ms, and 1.68s
to ignore fast transients on V
.
CC
o Available in Three Output Configurations
Push-Pull RESET
The MAX6841–MAX6845 assert a reset signal whenev-
er the V
supply voltage declines below a preset or
CC
Push-Pull RESET
Open-Drain RESET
adjustable threshold or whenever manual reset (MR) is
asserted. Reset remains asserted for a fixed timeout
o Guaranteed Reset Valid to V
= 0.55V
CC
delay after V
has risen above the reset threshold and
CC
(Active Low)
when manual reset is deasserted. Five timeout periods
are available for each part: 150µs (voltage detector ver-
sion), 1.5ms, 30ms, 210ms, and 1.68s (typ).
o Manual Reset Input
o Immune to Short V
Transients
CC
The MAX6841/MAX6843 have an active-low push-pull
reset output. The MAX6841/MAX6842/MAX6844 have
an active-high push-pull reset output, and the
MAX6842/MAX6845 have an active-low open-drain
reset output. The active-low open-drain reset output
requires a pullup resistor that can be connected to a
o Space-Saving 5-Pin SOT23 Package
Ordering Information
PART
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
PIN-PACKAGE
5 SOT23-5
5 SOT23-5
5 SOT23-5
5 SOT23-5
5 SOT23-5
MAX6841_UKD_-T
MAX6842_UKD_-T
MAX6843UKD_-T
MAX6844UKD_-T
MAX6845UKD_-T
voltage from 0 to V
.
CC
The low supply current (5.7µA) and small package
(SOT23-5) make the MAX6841–MAX6845 ideal for use
in portable equipment.
Note: Insert desired suffix letter (from the Threshold Suffix Guide
and the Active Timeout Period tables) into the blanks to com-
plete the part number. For example, the MAX6842GUKD1 has a
reset threshold of 1.11V and a typical reset timeout period of
1.5ms. Sample stock is generally available on standard versions
only (see the Standard Versions table). Standard versions
require a minimum order increment of 2.5k units. Nonstandard
versions must be ordered in 10k-unit increments. Contact factory
for availability. All parts are offered in tape-and-reel only.
Applications
Computers
Controllers
Intelligent Instruments
Critical µP and µC Power Monitoring
Portable/Battery-Powered Equipment
Telecom/Networking Equipment
Basestations
Pin Configurations
TOP VIEW
RESET
Servers/Workstations
RESET
GND
1
2
3
5
4
V
1
2
3
5
V
CC
CC
(RESET)
MAX6841
MAX6842
MAX6843
MAX6844
MAX6845
GND
Selector Guide and Typical Operating Circuit appear at end
of data sheet.
RESET
MR
RESET IN
4
MR
SOT23-5
SOT23-5
( ) ARE FOR 6844
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Ultra-Low-Voltage µP Reset Circuits and
Voltage Detectors
ABSOLUTE MAXIMUM RATINGS
Terminal Voltage (with respect to GND)
Continuous Power Dissipation (T = +70°C)
A
V
.......................................................................-0.3V to +6V
5-Pin SOT23 (derate 7.1mW/°C above +70°C)............571mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
CC
MR, RESET IN, RESET (open-drain).........................-0.3V to +6V
Push-Pull RESET and RESET .....................-0.3V to (V + 0.3V)
Input Current (all pins) ........................................................20mA
Output Current (RESET, RESET).........................................20mA
CC
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
= +0.55V to +1.8V, T = -40°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.) (Note 1)
A A
CC
PARAMETER
SYMBOL
CONDITIONS
MAX6843/MAX6845
MAX6841/MAX6842/MAX6844 (Note 2)
MIN
0.55
0.75
TYP
MAX
1.80
1.80
20
UNITS
Supply Voltage Range
V
V
CC
V
V
V
I
= 0.9V, no load, reset not asserted
= 1.5V, no load, reset not asserted
= 1.8V, no load, reset not asserted
5.7
CC
CC
CC
Supply Current
I
µA
V
7.3
20
CC
8.1
20
1.350
1.275
1.080
1.020
0.810
0.765
181.2
-25
1.388
1.313
1.110
1.050
0.833
0.788
187.4
1.425
1.350
1.140
1.080
0.855
0.810
191.5
+25
H
Reset Threshold
G
F
(V
Falling)
CC
V
TH
E
D, T = 0°C to +85°C
A
RESET IN Threshold
V
MAX6843/MAX6844/MAX6845 (Note 3)
mV
nA
RSTIN
I
RSTIN
RESET IN Leakage Current
Reset Threshold Hysteresis
V
0.75
150
%V
TH
HYS
V
falling, step signal from (V + 10%)
TH
CC
V
or RESET IN to Reset Delay
µs
CC
to (V - 10%) within 1µs
TH
D0 (voltage detector)
0.15
1.5
D1
D2
D3
D4
1
2
Reset Active Timeout Period
t
20
30
40
ms
RP
140
1120
210
1680
280
2240
V
0.3 × V
CC
IL
MR Input Voltage (Note 3)
V
V
0.7 × V
IH
CC
MR Minimum Input Pulse Width
MR Glitch Rejection
MR driven from V to 0 (Note 3)
1
µs
ns
ns
kΩ
CC
MR driven from V to 0 (Note 3)
150
500
20
CC
MR to Reset Delay
MR driven from V to 0 (Note 3)
CC
MR Pullup Resistance to V
10
26
CC
2
_______________________________________________________________________________________
Ultra-Low-Voltage µP Reset Circuits and
Voltage Detectors
ELECTRICAL CHARACTERISTICS (continued)
(V
= +0.55V to +1.8V, T = -40°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.) (Note 1)
A A
CC
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
V
V
≥ 0.55V, I
≥ 0.83V, I
= 10µA, reset asserted
0.2 × V
CC
CC
SINK
SINK
CC
CC
Open-Drain RESET Output
Voltage
V
V
OL
= 80µA, reset asserted
0.2 × V
Open-Drain RESET Output
Leakage Current
I
V
> V , reset not asserted
1
µA
V
LKG
CC
TH
V
V
V
≥ 0.55V, I
≥ 0.83V, I
≥ 0.83V, I
= 10µA, reset asserted
= 80µA, reset asserted
0.2 × V
0.2 × V
CC
CC
SINK
CC
CC
V
OL
SINK
Push-Pull RESET Output Voltage
= 40µA, reset not
= 10µA, reset
= 40µA, reset
CC
SOURCE
SOURCE
SOURCE
V
V
0.8 × V
0.8 × V
0.8 × V
OH
CC
CC
CC
asserted
V
≥ 0.75V, I
CC
asserted
OH
V
≥ 0.83V, I
CC
Push-Pull RESET Output Voltage
V
asserted
V
≥ 0.83V, I
= 80µA, reset not
SINK
CC
V
0.2 × V
OL
CC
asserted
Note 1: 100% production tested at +25°C. Overtemperature limits are guaranteed by design.
Note 2: The active-low output RESET has V = 0.55V (MAX6841/MAX6842).
CC(MIN)
Note 3: For V
> 0.788V, T = 0°C to +85°C, and for V
> 0.833V, T = -40°C to +85°C.
CC A
CC
A
Typical Operating Characteristics
(V
= 1.5V, T = +25°C, unless otherwise noted.)
CC
A
SUPPLY CURRENT
vs. TEMPERATURE
POWER-DOWN RESET DELAY
vs. TEMPERATURE
NORMALIZED RESET TIMEOUT PERIOD
vs. TEMPERATURE
9
350
300
250
200
150
100
50
1.06
1.04
1.02
1.00
0.98
0.96
0.94
8
7
6
5
4
3
2
1
0
V
= 1.8V
CC
D2 OPTION
D3 OPTION
V
OD
= 10mV
V
= 1.5V
CC
V
= 20mV
OD
V
= 0.9V
CC
D4 OPTION
V
= 100mV
OD
V
= OVERDRIVE (mV)
OD
0
-40
-20
0
20
40
60
80
-40
-20
0
20
40
60
80
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
_______________________________________________________________________________________
3
Ultra-Low-Voltage µP Reset Circuits and
Voltage Detectors
Typical Operating Characteristics (continued)
(V
= 1.5V, T = +25°C, unless otherwise noted.)
A
CC
NORMALIZED V RESET THRESHOLD
CC
NORMALIZED RESET IN THRESHOLD
vs. TEMPERATURE
POWER-UP/POWER-DOWN
vs. TEMPERATURE
CHARACTERISTICS (MAX6843AUKD3)
MAX6841-45 toc06
1.015
1.015
1.010
1.005
1.000
0.995
0.990
0.985
V
= 0.833V
TH
1.010
1.005
1.000
0.995
0.990
0.985
V
CC
1V/div
RESET
1V/div
-40
-20
0
20
40
60
80
-40
-20
0
20
40
60
80
200ms/div
TEMPERATURE (°C)
TEMPERATURE (°C)
Pin Description
PIN
NAME
FUNCTION
MAX6841 MAX6843
MAX6842 MAX6845
MAX6844
Push-Pull (MAX6841) or Open-Drain (MAX6842) Active-Low Reset Output. RESET
changes from high to low when V drops below the selected reset threshold or
CC
1
—
—
MR is pulled low. RESET remains low for the reset timeout period after V
exceeds the device reset threshold and MR is released high.
CC
RESET
Push-Pull (MAX6843) or Open-Drain (MAX6845) Active-Low Reset Output. RESET
changes from high to low when RESET IN drops below the 187.4mV reset
—
1
—
threshold (referenced to V ) or MR is pulled low. RESET remains low for the
CC
reset timeout period after RESET IN exceeds the reset threshold and MR is
released high.
2
3
2
2
GND
Ground
Push-Pull Active-High Reset Output. RESET changes from low to high when V
input drops below the selected reset threshold or MR is pulled low. RESET
remains high for the reset timeout period after V exceeds the device reset
CC
CC
—
—
threshold and MR is released high.
RESET
Push-Pull Active-High Reset Output. RESET changes from low to high when the
RESET IN input drops below the 187.4mV reset threshold (referenced to V ).
CC
RESET remains high for the reset timeout period after RESET IN exceeds the reset
threshold.
—
—
—
1
3
Adjustable Reset Input. High-impedance input for reset comparator. Connect this
pin to an external resistive-divider network to set the reset threshold voltage; the
RESET IN typical threshold is 187.4mV (referenced to V ). The MAX6843/MAX6844/
CC
3
MAX6845 assert a reset signal when the V
its threshold voltage.
to RESET IN differential falls below
CC
Active-Low Manual Reset Input. Internal 20kΩ pullup to V . Pull low to force a
CC
reset. Reset remains active as long as MR is low and for the reset timeout period
4
5
4
5
4
5
MR
after MR goes high. Leave unconnected or connect to V
if unused.
CC
V
Supply Voltage. Monitored supply for the MAX6841/MAX6842.
CC
4
_______________________________________________________________________________________
Ultra-Low-Voltage µP Reset Circuits and
Voltage Detectors
Functional Diagrams
MR
MR
V
V
CC
CC
MR
PULLUP
MAX6841
MAX6842
MR
MAX6843
MAX6844
MAX6845
PULLUP
MANUAL
RESET
DETECT
MANUAL
RESET
DETECT
V
V
= 187.4mV
REF
REF
RESET IN
RESET
TIMEOUT
PERIOD
RESET
TIMEOUT
PERIOD
RESET
RESET
RESET
OUTPUT
RESET
OUTPUT
RESET
RESET
GND
GND
tion, connect a normally open momentary switch from
MR to ground; external debounce circuitry is not
required. If MR is driven from long cables or the device
is used in a noisy environment, connect a 0.1µF capac-
itor from MR to ground to provide additional noise
immunity.
Detailed Description
Reset Output
A microprocessor’s (µP’s) reset input starts the µP in a
known state. The MAX6841–MAX6845 assert a reset dur-
ing power-up, power-down, and brownout conditions.
When the V supply voltage falls below a preset thresh-
CC
RESET IN
The MAX6843/MAX6844/MAX6845 feature a RESET IN
input, which allows users to adjust the reset threshold
voltage. The internal reference voltage is 187.4mV with
old (MAX6841/MAX6842) or RESET IN falls below the
adjustable threshold (MAX6843/MAX6844/MAX6845),
reset asserts and stays asserted for a fixed timeout delay
(Table 2) after V
or RESET IN has risen above the
CC
respect to V . An external resistive-divider network
CC
reset threshold. The MAX6841–MAX6845 are available
with five typical timeout options for each part: 150µs
(voltage detector), 1.5ms, 30ms, 210ms, and 1.68s.
can be used to set voltage monitoring thresholds, as
shown in Figure 1. The resistive-divider network must
be referenced to V . As V
falls, the voltage at
CC
CC
The MAX6841/MAX6842 have two reset outputs
(RESET and RESET); one is the inverse of the other.
The MAX6841 has one active-high push-pull output and
one active-low push-pull output. The MAX6842 has one
active-high push-pull output and one active-low open-
drain output. The MAX6843 features an active-low
push-pull output. The MAX6844 features an active-
high push-pull output, and the MAX6845 has an active-
low open-drain output stage. Connect a pullup resistor
from the open-drain RESET output to any voltage
between 0 and 6V.
V
CC
R1
R2
V
CC
RESET IN
MAX6843
MAX6844
MAX6845
RESET
(RESET)
Manual Reset Input
Many µP-based systems require a manual reset capa-
bility, allowing the operator, a test technician, or exter-
nal logic circuitry to initiate a reset. Reset remains
asserted while MR is low, and for a fixed timeout delay
after MR returns high. This input has an internal 20kΩ
pullup resistor, so it can be left open if it is not used.
MR can be driven with CMOS logic level or with open-
drain/collector outputs. To create a manual reset func-
MR
GND
R2
( ) ARE FOR
MAX6844
R1 =
V
CC-TH
REF
- 1
V
WHERE V = 187.4mV (WITH RESPECT TO V ) AND
REF
CC
V
IS THE V THRESHOLD.
CC-TH
CC
Figure 1. Setting the Adjustable Threshold Externally
_______________________________________________________________________________________
5
Ultra-Low-Voltage µP Reset Circuits and
Voltage Detectors
RESET IN decreases. The MAX6843/MAX6844/
MAX6845 assert a reset when the voltage at RESET IN
most applications, because most µP and other circuitry
are inoperative with V lower than 0.55V. However, in
CC
falls below the RESET IN threshold (V
). The low-
applications in which RESET must be valid down to 0,
adding a pulldown resistor to RESET causes any stray
leakage currents to flow to ground, holding RESET low
(Figure 3). R3’s value is not critical; 200kΩ is large
enough not to load RESET and small enough to pull
RESET to ground.
RSTIN
leakage current at RESET IN allows for relatively large-
value resistors to be used, which reduces power
consumption. For example, for V
= 0.9V, if R2 =
CC-TH
100kΩ, then R1 = 26.3kΩ.
Applications Information
V
Falling Transients
CC
The MAX6841–MAX6845 are relatively immune to short-
duration falling V transients (glitches). Figure 2
CC
V
CC
shows typical transient duration vs. reset comparator
overdrive, for which the MAX6841–MAX6845 do not
generate a reset pulse. The graph was generated using
MAX6841
MAX6843
a falling pulse applied to V , starting 0.1V above the
CC
actual reset threshold and ending below it by the mag-
nitude indicated (reset comparator overdrive). The
graph indicates the maximum pulse width that a falling
RESET
R3
GND
V
transient can have without causing a reset pulse.
CC
As the magnitude of the transient increases (goes fur-
ther below the reset threshold), the maximum allowable
pulse width decreases. A 0.1µF bypass capacitor
Figure 3. RESET Valid to V
= 0
CC
mounted as close as possible to the V
additional transient immunity.
pin provides
CC
A 200kΩ pullup resistor to V
is also recommended
CC
Ensuring a Valid Reset Output
Down to V = 0
for the MAX6841/MAX6842/MAX6844 if push-pull
CC
falls below 0.55V, the MAX6841/MAX6843
RESET is required to remain valid for V
≤ 0.75V.
CC
When V
CC
Interfacing to µPs with Bidirectional
Reset Pins
push-pull RESET output no longer sinks current; it
becomes an open circuit. Therefore, high-impedance
CMOS-logic inputs connected to RESET can drift to
undetermined voltages. This presents no problem in
Because the RESET output on the MAX6842/MAX6845
is open drain, these devices interface easily with µPs
that have bidirectional reset pins. Connecting the µP
supervisor’s RESET output directly to the µP’s RESET
pin with a single pullup resistor allows either device to
assert reset (Figure 4).
MAXIMUM TRANSIENT DURATION
vs. OVERDRIVE
600
550
RESET OCCURS ABOVE THIS LINE
500
450
400
350
300
250
200
150
100
V
CC
V
V
CC
CC
MAX6842
MAX6845
µP
RESET
INPUT
RESET
GND
GND
1
10
OVERDRIVE V - V (mV)
100
TH
CC
Figure 4. Interfacing to Microprocessors with Bidirectional
Reset I/0
Figure 2. Maximum Transient Duration vs. Overdrive
6
_______________________________________________________________________________________
Ultra-Low-Voltage µP Reset Circuits and
Voltage Detectors
+5.0V
Table 1. Threshold Suffix Guide
0.9V
SUFFIX
RESET THRESHOLD (V)
V
V
CC
CC
I
1.388
1.313
1.110
1.050
0.833
0.788
H
G
F
R
PULLUP
MAX6842
MAX6845
µP
RESET
RESET
E
D
GND
GND
Table 2. Active Timeout Period Guide
Figure 5. Using the MAX6842/MAX6845 Open-Drain RESET
Output with Multiple Supplies
RESET ACTIVE TIMEOUT PERIOD (ms)
SUFFIX
MIN
—
TYP
0.15
1.5
MAX
—
D0
D1
D2
D3
D4
1
2
Using the MAX6842/MAX6845 Open-Drain
RESET Output with Multiple Supplies
20
30
40
140
1120
210
1680
280
2240
Generally, the pullup connected to the MAX6842/
MAX6845 connects to the supply voltage being moni-
tored at the IC’s V
pin. However, some systems use
CC
the open-drain output to level-shift from the monitored
supply to reset circuitry powered by some other supply
Table 3. Standard Versions
(Figure 5). Note that as the MAX6842/MAX6845’s V
DEVICE
TOP MARK
CC
decreases, so does the IC’s ability to sink current at
RESET. Also, with any pullup, RESET is pulled high as
CC
depends on the pullup resistor value and the voltage to
which it is connected.
MAX6841HUKD0
MAX6841HUKD3
MAX6841FUKD0
MAX6841FUKD3
MAX6841DUKD0
MAX6841DUKD3
MAX6842HUKD0
MAX6842HUKD3
MAX6842FUKD0
MAX6842FUKD3
MAX6842DUKD0
MAX6842DUKD3
MAX6843UKD0
MAX6843UKD3
MAX6844UKD0
MAX6844UKD3
MAX6845UKD0
MAX6845UKD3
AEDR
AEDS
AEDP
AEDQ
AEDN
AEDO
AEDX
AEDY
AEDV
AEDW
AEDT
AEDU
AEDZ
AEEA
AEEB
AEEC
AEED
AEEE
V
decays toward 0. The voltage where this occurs
Chip Information
TRANSISTOR COUNT: 788
PROCESS: BiCMOS
_______________________________________________________________________________________
7
Ultra-Low-Voltage µP Reset Circuits and
Voltage Detectors
Selector Guide
ADJUSTABLE
RESET INPUT
PUSH-PULL
RESET
PUSH-PULL
RESET
OPEN-DRAIN
PART
MANUAL RESET
RESET
MAX6841
MAX6842
MAX6843
MAX6844
MAX6845
✔
✔
✔
✔
✔
—
—
✔
✔
✔
✔
—
✔
✔
✔
—
✔
—
—
✔
—
—
✔
—
—
Typical Operating Circuit
V
IN
3.3V
0.9V
DC/DC
CONVERTER
CORE
SUPPLY
I/O
SUPPLY
V
CC
µP
MAX6842D/E
RESET
RESET
RESET
PUSHBUTTON
SWITCH
GND
MR
GND
8
_______________________________________________________________________________________
Ultra-Low-Voltage µP Reset Circuits and
Voltage Detectors
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 9
© 2002 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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