MAX6887LETE [MAXIM]
Hex/Quad, Power-Supply Supervisory Circuits; 六/四路,电源设备监控电路型号: | MAX6887LETE |
厂家: | MAXIM INTEGRATED PRODUCTS |
描述: | Hex/Quad, Power-Supply Supervisory Circuits |
文件: | 总14页 (文件大小:789K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
19-0291; Rev 1; 3/07
Hex/Quad, Power-Supply Supervisory Circuits
General Description
Features
The MAX6887/MAX6888 multivoltage supply supervi-
sors provide several voltage-detector inputs, one watch-
dog input, and three outputs. Each voltage-detector
input offers a factory-set undervoltage and overvoltage
threshold. Manual reset and margin disable inputs offer
additional flexibility.
♦ Hex/Quad Voltage Detectors
♦ Undervoltage and Overvoltage Thresholds
♦ 1% Threshold Accuracy
♦ Margining Disable and Manual Reset Input
♦ Watchdog Timer
The MAX6887 offers six voltage-detector inputs, while
the MAX6888 offers four inputs. Output RESET asserts
when any input voltage drops below its respective
undervoltage threshold or manual reset MR is asserted.
Output OV asserts when any input voltage exceeds its
respective overvoltage threshold. Monitor standard
supply voltages listed in the Selector Guide.
♦ Open-Drain RESET, OV, and WDO Outputs
♦ 180ms (min) Reset Timeout Period
♦ Few External Components
♦ Small 5mm x 5mm, 16-Pin Thin QFN Packages
The MAX6887/MAX6888 offer a watchdog timer with an
initial and normal timeout periods of 102.4s and 1.6s,
respectively. Watchdog output WDO asserts when the
watchdog timer expires. Connect WDO to manual reset
input MR to generate resets when the watchdog timer
expires. RESET, OV, and WDO are active-low, open-
drain outputs.
Ordering Information
PIN-
PACKAGE
PKG
CODE
PART
TEMP RANGE
The MAX6887/MAX6888 are available in a 5mm x 5mm
x 0.8mm, 16-pin thin QFN package and operate over
the extended -40°C to +85°C temperature range.
MAX6887_ETE
MAX6888_ETE
-40°C to +85°C 16 Thin QFN
-40°C to +85°C 16 Thin QFN
T1655-2
T1655-2
Applications
Multivoltage Systems
Note: Insert the desired letter from the Selector Guide into the
blank to complete the part number.
Telecom
Networking
Pin Configurations and Typical Operating Circuit appear at
end of data sheet.
Servers/Workstations/Storage Systems
Selector Guide
NOMINAL INPUT VOLTAGE (V)*
TOL
NOMINAL INPUT VOLTAGE (V)*
TOL
PART
PART
MAX6887IETE 5.0
(%)
(%)
IN1 IN2
IN3
2.5
2.5
1.8
1.8
1.8
1.5
Adj
Adj
Adj
IN4
1.8
Adj
Adj
1.5
Adj
Adj
Adj
Adj
Adj
IN5
Adj
Adj
Adj
Adj
Adj
Adj
Adj
Adj
Adj
IN6
Adj
Adj
Adj
Adj
Adj
Adj
Adj
Adj
Adj
IN1 IN2
IN3
2.5
2.5
1.8
1.8
1.8
1.5
Adj
Adj
Adj
IN4
1.8
Adj
Adj
1.5
Adj
Adj
Adj
Adj
Adj
IN5
Adj
Adj
Adj
Adj
Adj
Adj
Adj
Adj
Adj
IN6
Adj
Adj
Adj
Adj
Adj
Adj
Adj
Adj
Adj
MAX6887AETE 5.0
3.3
3.3
3.3
2.5
2.5
2.5
2.5
1.8
5
5
5
5
5
5
5
5
5
3.3
3.3
3.3
2.5
2.5
2.5
2.5
1.8
10
10
10
10
10
10
10
10
10
MAX6887BETE 5.0
MAX6887CETE 5.0
MAX6887DETE 3.3
MAX6887EETE 3.3
MAX6887FETE 3.3
MAX6887GETE 3.3
MAX6887HETE 3.3
MAX6887JETE 5.0
MAX6887KETE 5.0
MAX6887LETE 3.3
MAX6887METE 3.3
MAX6887NETE 3.3
MAX6887OETE 3.3
MAX6887PETE 3.3
MAX6887QETE Adj Adj
MAX6887RETE Adj Adj
*See thresholds options tables (Tables 1 and 2) for actual undervoltage and overvoltage thresholds.
Selector Guides continued at end of data sheet.
________________________________________________________________ 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.
Hex/Quad, Power-Supply Supervisory Circuits
ABSOLUTE MAXIMUM RATINGS
(All voltages referenced to GND.)
Maximum Junction Temperature .....................................+150°C
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
IN1–IN6, V , RESET, OV, WDO .............................-0.3V to +6V
CC
WDI, MR, MARGIN ...................................................-0.3V to +6V
BP.............................................................................-0.3V to +3V
Input/Output Current (all pins).......................................... 20mA
Continuous Power Dissipation (T = +70°C)
A
16-Pin 5mm x 5mm Thin QFN
(derate 20.8mW/°C above +70°C)..............................1667mW
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 –V
IN1 IN4
or V
= 2.7V to 5.8V, WDI = GND, MARGIN = MR = BP, T = -40°C to +85°C, unless otherwise noted. Typical values are
CC A
at T = +25°C.) (Notes 1, 2)
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
V
Operating Voltage Range
(Note 3)
Voltage on either one of IN1–IN4 or V
guarantee the part is fully operational
to
CC
2.7
5.8
Supply Current
I
V
= 5.8V, IN2–IN6 = GND, no load
IN1
0.9
1.2
+1
mA
CC
IN1–IN6, IN_ falling, T = +25°C to +85°C
-1
A
Threshold Accuracy
(See the Selector Guide)
V
% V
TH
TH
IN1–IN6, IN_ falling, T = -40°C to +85°C
-1.5
+1.5
A
Threshold Hysteresis
Threshold Tempco
V
0.3
10
% V
TH-HYST
TH
∆V /°C
ppm/°C
TH
For V
< highest V
and
IN_
IN1–IN4
< V (not ADJ), thresholds are not set
CC
IN_ Input Impedance
R
V
130
200
300
kΩ
IN
IN_
as adjustable
IN5, IN6 (MAX6887 only)
IN_ Input Leakage Current
I
-150
+150
2.5
nA
IN
IN1–IN4 set as adjustable thresholds
Power-Up Delay
t
V
≥ 2.5V
CC
ms
µs
D-PO
IN_ to RESET or OV Delay
RESET Timeout Period
OV Timeout Period
t
IN_ falling/rising, 100mV overdrive
20
200
25
D-R
t
180
-1
220
ms
µs
RP
OP
t
RESET, OV, and WDO Output
Low
V
I
= 4mA, output asserted
0.4
+1
V
OL
SINK
RESET, OV, and WDO Output
Open-Drain Leakage Current
I
Output high impedance
µA
LKG
2
_______________________________________________________________________________________
Hex/Quad, Power-Supply Supervisory Circuits
ELECTRICAL CHARACTERISTICS (continued)
(V –V
IN1 IN4
or V
= 2.7V to 5.8V, WDI = GND, MARGIN = MR = BP, T = -40°C to +85°C, unless otherwise noted. Typical values are
CC A
at T = +25°C.) (Notes 1, 2)
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
V
0.6
IL
IH
MR, MARGIN, WDI Input Voltage
V
V
1.4
1
MR Input Pulse Width
t
µs
ns
ns
µA
MR
MR Glitch Rejection
100
200
10
MR to RESET or OV Delay
MR to Internal BP Pullup Current
t
D-MR
I
V
V
V
= 1.4V
5
5
15
15
15
MR
MR
MARGIN to Internal BP Pullup
Current
I
= 1.4V
= 0.6V
WDI
10
10
µA
MARGIN
MARGIN
WDI Pulldown Current
WDI Input Pulse Width
I
t
5
µA
ns
WDI
50
Initial
92.16
1.44
102.4 112.64
1.6 1.76
WDI
Watchdog Timeout Period
s
t
Normal
WD
Note 1: 100% production tested at T = +25°C and T = +85°C. Specifications at T = -40°C are guaranteed by design.
A
A
A
Note 2: Device may be supplied from any one of IN1–IN4 or V
.
CC
Note 3: The internal supply voltage, measured at V , equals the maximum of IN1–IN4.
CC
Note 4: Versions Q and R require that power be applied through V
.
CC
Typical Operating Characteristics
(V –V
IN1 IN4
or V
= 5V, WDI = GND, MARGIN = MR = BP, T = +25°C, unless otherwise noted.)
CC A
V
SUPPLY CURRENT
CC
RESET TIMEOUT PERIOD
vs. TEMPERATURE
IN1–IN4 SUPPLY CURRENT
vs. IN1–IN4 SUPPLY VOLTAGE
CC
vs. V SUPPLY VOLTAGE
1.00
0.95
0.90
0.85
0.80
0.75
0.70
1.00
0.95
0.90
0.85
0.80
0.75
0.70
220
215
210
205
200
195
190
185
180
T
= +85°C
A
T
= +85°C
A
T
= +25°C
T = +25°C
A
A
T = -40°C
A
T
= -40°C
A
2.6
3.6
4.6
5.6
2.6
3.6
4.6
5.6
-40
-15
10
35
60
85
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
_______________________________________________________________________________________
3
Hex/Quad, Power-Supply Supervisory Circuits
Typical Operating Characteristics (continued)
(V –V
IN1 IN4
or V
= 5V, WDI = GND, MARGIN = MR = BP, T = +25°C, unless otherwise noted.)
A
CC
IN_ TO RESET OR OV
PROPAGATION DELAY vs. TEMPERATURE
WATCHDOG TIMEOUT PERIOD
vs. TEMPERATURE
NORMALIZED IN_ THRESHOLD
vs. TEMPERATURE
30
29
28
27
26
25
24
23
22
21
20
1.700
1.675
1.650
1.625
1.600
1.575
1.550
1.525
1.500
1.005
1.004
1.003
1.002
1.001
1.000
0.999
0.998
0.997
0.996
0.995
100mV OVERDRIVE
-40
-15
10
35
60
85
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
MAXIMUM IN_ TRANSIENT
vs. IN_THRESHOLD OVERDRIVE
MR TO RESET OUTPUT PROPAGATION
DELAY vs. TEMPERATURE
OUTPUT-VOLTAGE LOW vs. SINK CURRENT
200
175
150
125
100
75
400
350
300
250
200
150
100
50
3.00
2.75
2.50
2.25
2.00
1.75
1.50
1.25
1.00
PO_ ASSERTION OCCURS
ABOVE THIS LINE
50
25
0
0
1
10
100
1000
0
2
4
6
8
10
12
14
-40
-15
10
35
60
85
IN_ THRESHOLD OVERDRIVE (mV)
SINK CURRENT (mA)
TEMPERATURE (°C)
Pin Description
PIN
MAX6887 MAX6888
NAME
FUNCTION
Open-Drain, Active-Low Reset Output. RESET asserts when any input voltage falls below its
undervoltage threshold or when MR is pulled low. RESET remains low for 200ms after all
assertion-causing conditions are cleared. An external pullup resister is required.
1
2
1
2
RESET
Open-Drain, Active-Low Watchdog Timer Output. Logic output for the watchdog timer function.
WDO goes low when WDI is not strobed high-to-low or low-to-high within the watchdog timeout
period.
WDO
Open-Drain Active-Low Overvoltage Output. OV asserts when any input voltage exceeds its
3
4
3
4
OV
overvoltage threshold. OV remains low for 25µs after all overvoltage conditions are cleared.
An external pullup resistor is required.
GND
Ground
4
_______________________________________________________________________________________
Hex/Quad, Power-Supply Supervisory Circuits
Pin Description (continued)
PIN
NAME
FUNCTION
MAX6887 MAX6888
Manual Reset Input. Pull MR low to assert RESET. Connect MR to WDO to generate resets
when the watchdog timer expires. Leave MR unconnected or connect to DBP if unused. MR is
internally pulled up to BP through a 10µA current source.
5
5
MR
Margin Input. When MARGIN is pulled low, RESET is held in its existing state independent of
subsequent changes in monitored input voltages or the watchdog timer expiration. MARGIN is
internally pulled up to BP through a 10µA current source. Leave MARGIN unconnected or
connect to BP if unused. MARGIN overrides MR if both are asserted at the same time.
6
6
MARGIN
Watchdog Timer Input. Logic input for the watchdog timer function. If WDI is not strobed with a
valid low-to-high or high-to-low transition within the selected watchdog timeout period, WDO
asserts. WDI is internally pulled down to GND through a 10µA current sink.
7
8
7
8
WDI
I.C.
Internal Connection. Leave unconnected.
Internal Power-Supply Voltage. Bypass V
to GND with a 1µF ceramic capacitor as close to
CC
the device as possible. V
from the highest of the monitored IN1–IN4 voltages. Do not use V
supplies power to the internal circuitry. V is internally powered
CC
CC
9
9
V
CC
to supply power to external
CC
circuitry. To externally supply V , see the Powering the MAX6887/MAX6888 section.
CC
Bypass Voltage. The internally generated voltage at BP supplies power to internal logic and
output RESET. Connect a 1µF capacitor from BP to GND as close to the device as possible. Do
not use BP to supply power to external circuitry.
10
11
10
—
BP
Input Voltage Detector 6. IN6 monitors both undervoltage and overvoltage conditions. See the
thresholds options (Tables 1 and 2) for available thresholds. IN6 cannot power the device. For
improved noise immunity, bypass IN6 to GND with a 0.1µF capacitor installed as close to the
device as possible.
IN6
IN5
IN4
IN3
IN2
IN1
Input Voltage Detector 5. IN5 monitors both undervoltage and overvoltage conditions. See the
thresholds options (Tables 1 and 2) for available thresholds. IN5 cannot power the device. For
improved noise immunity, bypass IN5 to GND with a 0.1µF capacitor installed as close to the
device as possible.
12
13
14
15
16
—
13
14
15
16
Input Voltage Detector 4. IN4 monitors both undervoltage and overvoltage conditions. See the
thresholds options (Tables 1 and 2) for available thresholds. Power the device through IN1–IN4
or V
(see the Powering the MAX6887/MAX6888 section). For improved noise immunity,
CC
bypass IN4 to GND with a 0.1µF capacitor installed as close to the device as possible.
Input Voltage Detector 3. IN3 monitors both undervoltage and overvoltage conditions. See the
thresholds options (Tables 1 and 2) for available thresholds. Power the device through IN1–IN4
or V
(see the Powering the MAX6887/MAX6888 section). For improved noise immunity,
CC
bypass IN3 to GND with a 0.1µF capacitor installed as close to the device as possible.
Input Voltage Detector 2. IN2 monitors both undervoltage and overvoltage conditions. See the
thresholds options (Tables 1 and 2) for available thresholds. Power the device through IN1–IN4
or V
(see the Powering the MAX6887/MAX6888 section). For improved noise immunity,
CC
bypass IN2 to GND with a 0.1µF capacitor installed as close to the device as possible.
Input Voltage Detector 1. IN1 monitors both undervoltage and overvoltage conditions. See the
thresholds options (Tables 1 and 2) for available thresholds. Power the device through IN1–IN4
or V
(see the Powering the MAX6887/MAX6888 section). For improved noise immunity,
CC
bypass IN1 to GND with a 0.1µF capacitor installed as close to the device as possible.
—
—
11, 12
—
N.C.
EP
No Connection. Not internally connected.
Exposed Paddle. Internally connected to GND. Connect EP to GND or leave unconnected.
_______________________________________________________________________________________
5
Hex/Quad, Power-Supply Supervisory Circuits
Functional Diagram
WDI
*IN_
DETECTOR
IN1
MARGIN
MR
RESET
RESET TIMING BLOCK
IN2
IN3
IN4
IN2 DETECTOR
IN3 DETECTOR
IN4 DETECTOR
IN5 DETECTOR
OV
IN5
(N.C.)
OV TIMING BLOCK
IN6
(N.C.)
IN6 DETECTOR
WDO
WDO TIMING BLOCK
V
CC
REFERENCE
1µF
2.55V
LDO
MAX6887
MAX6888
BP
1µF
( ) MAX6888 ONLY
GND
*FOR ADJUSTABLE INPUTS REFER TO THE ADJUSTABLE THRESHOLD INPUTS SECTION.
6
_______________________________________________________________________________________
Hex/Quad, Power-Supply Supervisory Circuits
The MAX6887/MAX6888 generate a supply voltage at
Detailed Description
BP for the internal logic circuitry. Bypass BP to GND with
The MAX6887/MAX6888 provide several supply-detector
a 1µF ceramic capacitor installed as close to the device
inputs, one watchdog input, and three outputs for power-
as possible. The nominal BP output voltage is +2.55V.
supply monitoring applications. The MAX6887 offers six
Do not use BP to provide power to external circuitry.
voltage-detector inputs, while the MAX6888 offers four.
Each voltage-detector input offers both an undervoltage
and overvoltage threshold.
Inputs
The MAX6887 offers six voltage-detector inputs, while
the MAX6888 offers four voltage-detector inputs. Each
voltage-detector input offers an undervoltage and over-
voltage threshold set at the factory to monitor standard
supply voltages (see the Selector Guide). The 5% and
10% tolerances are based on maximum and minimum
threshold values. Actual thresholds for the
MAX6887/MAX6888 are shown in Tables 1 and 2.
Inputs in the Selector Guide listing “Adj” allow an exter-
nal voltage-divider to be connected to set a user-
defined threshold.
The undervoltage and overvoltage thresholds are facto-
ry-set for monitoring standard supply voltages (see the
Selector Guide). Inputs in the Selector Guide that con-
tain “Adj” allow an external voltage-divider to be con-
nected to set a user-defined threshold.
RESET goes low when any input voltage drops below
its undervoltage threshold or when MR is brought low.
RESET stays low for 200ms after all assertion-causing
conditions have been cleared. OV goes low when an
input voltage rises above its overvoltage threshold. OV
typically stays low for 25µs (typ) after all inputs fall
back under their overvoltage thresholds.
Adjustable Threshold Inputs
Inputs listed in the Selector Guide containing “Adj” for
inputs allow external resistor voltage-dividers to be
connected at the voltage-detector inputs. These inputs
monitor any voltage supply higher than 0.6V (see
Figure 1). Use the following equation to set a voltage-
The MAX6887/MAX6888 offer a watchdog timer with
initial and normal timeout periods of 102.4s and 1.6s,
respectively. WDO goes low when the watchdog timer
expires and deasserts when WDI transitions from low-
to-high or high-to-low.
Powering the MAX6887/MAX6888
The MAX6887/MAX6888 derive power from the voltage-
detector inputs IN1–IN4 or through an externally sup-
V
IN
plied V . A virtual diode-ORing scheme selects the
CC
MAX6887
MAX6888
R1
R2
positive input that supplies power to the device (see
the Functional Diagram). The highest input voltage on
IN1–IN4 supplies power to the device. One of IN1–IN4
must be at least 2.7V to ensure proper operation.
IN_
Internal hysteresis ensures that the supply input that
initially powered the device continues to power the
device when multiple input voltages are within 50mV of
each other.
*V
REFUV
V
powers the analog circuitry and is the bypass con-
CC
nection for the MAX6887/MAX6888 internal supply.
Bypass V to GND with a 1µF ceramic capacitor
CC
installed as close to the device as possible. The inter-
nal supply voltage, measured at V , equals the maxi-
CC
*V
REFOV
mum of IN1–IN4. If V
is externally supplied, V
CC
CC
must be at least 200mV higher than any voltage
applied to IN1–IN4 and V must be brought up first.
CC
V
always powers the device when all IN_ are factory
set as “Adj.” Do not use the internally generated V
provide power to external circuitry.
CC
to
CC
*V
REFOV
AND V
ARE REFERENCED
REFUV
TO 0.6V ACCORDING TO THE DEVICE'S TOLERANCE
Figure 1. Adjusting the Monitored Threshold
_______________________________________________________________________________________
7
Hex/Quad, Power-Supply Supervisory Circuits
detector input (IN1–IN6) to monitor a user-defined sup-
ply voltage:
V
and V
are the undervoltage and overvolt-
REFOV
REFUV
age thresholds listed in Tables 1 and 2 that allow
adjustable thresholds. Their values are based on toler-
ances of 7.5% and 12.5% from a 0.6V reference.
See the Selector Guide to find which thresholds in
Tables 1 and 2 are adjustable.
⎛
⎞
⎟
R2
0.6V = V
×
MON
⎜
R1+R2
⎝
⎠
where V
is the desired voltage to be monitored.
Manual Reset (MR)
Many µP-based products require manual reset capability
to allow an operator or external logic circuitry to initiate a
reset. The manual reset input (MR) can be connected
directly to a switch without an external pullup resistor or
debouncing network. MR is internally pulled up to BP.
Leave unconnected if not used. MR is internally pulled
up to BP through a 10µA current source. MR is designed
to reject fast, falling transients (typically 100ns pulses)
and MR must be held low for a minimum of 1µs to assert
RESET. Connect a 0.1µF capacitor from MR to ground to
provide additional noise immunity. After MR transitions
from low to high, RESET remains asserted for the dura-
tion of its time delay.
MON
Use the following procedure to design the proper volt-
age-divider and calculate thresholds:
1) Pick a value for R2. Use the equation above with
the desired supply voltage to be monitored and
solve for R1. Use high-value resistors R1 and R2 to
minimize current consumption due to low leakage
currents.
2) To find the actual undervoltage and overvoltage
thresholds, use the following equations:
V
⎛
⎜
⎞
⎟
REFUV
V
= V
×
×
ACTUALUV
MON
⎝ 0.6V ⎠
V
⎛
⎞
Margin Output Disable (MARGIN)
MARGIN allows system-level testing while power sup-
plies exceed the normal operating ranges. Drive
MARGIN low to hold RESET, OV, and WDO in their
REFOV
0.6V
V
= V
MON
⎜
⎝
⎟
⎠
ACTUALOV
Table 1. MAX6887 Threshold Options
UV THRESHOLDS (V)
PART
OV THRESHOLDS (V)
IN1
IN2
IN3
IN4
IN5
IN6
IN1
IN2
IN3
IN4
IN5
IN6
MAX6887AETE
MAX6887BETE
MAX6887CETE
MAX6887DETE
MAX6887EETE
MAX6887FETE
MAX6887GETE
MAX6887HETE
MAX6887QETE
MAX6887IETE
MAX6887JETE
MAX6887KETE
MAX6887LETE
MAX6887METE
MAX6887NETE
MAX6887OETE
MAX6887PETE
MAX6887RETE
4.620
4.620
4.620
3.060
3.060
3.060
3.060
3.060
0.557
4.380
4.380
4.380
2.880
2.880
2.880
2.880
2.880
0.527
3.060
3.060
3.060
2.310
2.310
2.310
2.310
1.670
0.557
2.880
2.880
2.880
2.190
2.190
2.190
2.190
1.580
0.527
2.310
2.310
1.670
1.670
1.670
1.390
0.557
0.557
0.557
2.190
2.190
1.580
1.580
1.580
1.310
0.527
0.527
0.527
1.670
0.557
0.557
1.390
0.557
0.557
0.557
0.557
0.557
1.580
0.527
0.527
1.310
0.527
0.527
0.527
0.527
0.527
0.557
0.557
0.557
0.557
0.557
0.557
0.557
0.557
0.557
0.527
0.557
0.557
0.557
0.557
0.557
0.557
0.557
0.527
0.557
0.557
0.557
0.557
0.557
0.557
0.557
0.557
0.557
0.527
0.557
0.557
0.557
0.557
0.557
0.557
0.557
0.527
5.360
5.360
5.360
3.540
3.540
3.540
3.540
3.540
0.643
5.620
5.620
5.620
3.700
3.700
3.700
3.700
3.700
0.673
3.540
3.540
3.540
2.680
2.680
2.680
2.680
1.930
0.643
3.700
3.700
3.700
2.810
2.810
2.810
2.810
2.020
0.673
2.680
2.680
1.930
1.930
1.930
1.610
0.643
0.643
0.643
2.810
2.810
2.020
2.020
2.020
1.680
0.673
0.673
0.673
1.930
0.643
0.643
1.610
0.643
0.643
0.643
0.643
0.643
2.020
0.673
0.673
1.680
0.673
0.673
0.673
0.673
0.673
0.643
0.643
0.643
0.643
0.643
0.643
0.643
0.643
0.643
0.673
0.673
0.673
0.673
0.673
0.673
0.673
0.673
0.673
0.643
0.643
0.643
0.643
0.643
0.643
0.643
0.643
0.643
0.673
0.673
0.673
0.673
0.673
0.673
0.673
0.673
0.673
8
_______________________________________________________________________________________
Hex/Quad, Power-Supply Supervisory Circuits
Table 2. MAX6888 Threshold Options
UV THRESHOLDS (V)
OV THRESHOLDS (V)
PART
IN1
IN2
IN3
IN4
IN1
IN2
IN3
IN4
MAX6888AETE
MAX6888BETE
MAX6888CETE
MAX6888DETE
MAX6888EETE
MAX6888FETE
MAX6888GETE
MAX6888HETE
MAX6888QETE
MAX6888IETE
MAX6888JETE
MAX6888KETE
MAX6888LETE
MAX6888METE
MAX6888NETE
MAX6888OETE
MAX6888PETE
MAX6888RETE
4.620
4.620
4.620
3.060
3.060
3.060
3.060
3.060
0.527
4.380
4.380
4.380
2.880
2.880
2.880
2.880
2.880
0.557
3.060
3.060
3.060
2.310
2.310
2.310
2.310
1.670
0.527
2.880
2.880
2.880
2.190
2.190
2.190
2.190
1.580
0.557
2.310
2.310
1.670
1.670
1.670
1.390
0.557
0.557
0.527
2.190
2.190
1.580
1.580
1.580
1.310
0.527
0.527
0.557
1.670
0.557
0.557
1.390
0.557
0.557
0.557
0.557
0.527
1.580
0.527
0.527
1.310
0.527
0.527
0.527
0.527
0.557
5.360
5.360
5.360
3.540
3.540
3.540
3.540
3.540
0.673
5.620
5.620
5.620
3.700
3.700
3.700
3.700
3.700
0.643
3.540
3.540
3.540
2.680
2.680
2.680
2.680
1.930
0.673
3.700
3.700
3.700
2.810
2.810
2.810
2.810
2.020
0.643
2.680
2.680
1.930
1.930
1.930
1.610
0.643
0.643
0.673
2.810
2.810
2.020
2.020
2.020
1.680
0.673
0.673
0.643
1.930
0.643
0.643
1.610
0.643
0.643
0.643
0.643
0.673
2.020
0.673
0.673
1.680
0.673
0.673
0.673
0.673
0.643
existing state while system-level testing occurs. Leave
MARGIN unconnected or connect to BP if unused. An
internal 10µA current source pulls MARGIN to BP.
MARGIN overrides MR if both are asserted at the
same time. The state of RESET, OV, and WDO does not
change while MARGIN = GND.
RESET asserts when any monitored input is below its
undervoltage threshold or MR is asserted. RESET
remains asserted for 200ms after all assertion-causing
conditions have been cleared. Configure RESET to
assert when the watchdog timer expires by connecting
WDO to MR. RESET requires a pullup resistor.
WDO asserts when the watchdog timer expires. See
the Configuring the Watchdog Timer section for a com-
plete description. WDO requires a pullup resistor.
RESET, OV, and WDO Outputs
The MAX6887/MAX6888 feature three active-low open-
drain outputs: RESET, OV, and WDO. After power-up or
overvoltage/undervoltage conditions, RESET and OV
remain in their active states until their timeout periods
expire and no undervoltage/overvoltage conditions are
present (see Figure 2).
Configuring the Watchdog Timer
A watchdog timer monitors microprocessor (µP) soft-
ware execution for a stalled condition and resets the µP
if it stalls. Connect the watchdog timer output WDO to
the reset input or a nonmaskable interrupt of the µP.
The watchdog timer features independent initial and
normal watchdog timeout periods of 102.4s and 1.6s,
respectively.
OV asserts when any monitored input is above its over-
voltage threshold and remains asserted until all inputs
are below their thresholds and its respective 25µs time-
out period expires. Connect OV to MR to bring RESET
low during an overvoltage condition. OV requires a
pullup resistor (unless connected to MR).
_______________________________________________________________________________________
9
Hex/Quad, Power-Supply Supervisory Circuits
OVERVOLTAGE
THRESHOLD
V
IN
PRIMARY
THRESHOLD
OV
t
OP
RESET
t
RP
Figure 2. Output Timing Diagram
2.5V
.
2.5V
V
CC
OR IN1–IN4
V
CC
OR IN1–IN4
WDO
WDO
RESET
WDI
RESET
WDI
t
t
*t
WDI
t
t
RP
*t
DWI
D-PO
RP
WD
t
t
RP
*t
WDI
t
*t
WDI
D-PO
WD
WDO CONNECTED TO MR
WDO NOT CONNECTED TO MR
*t IS THE INITIAL WATCHDOG TIMER PERIOD
WDI
Figure 3. Watchdog, Reset, and Power-Up Timing Diagram
10 ______________________________________________________________________________________
Hex/Quad, Power-Supply Supervisory Circuits
At power-up, WDO goes high after t
(see Figure 3).
) applies imme-
Selector Guide (continued)
D-PO
The initial watchdog timeout period (t
WDI
NOMINAL INPUT
diately after WDO is high. The initial watchdog timeout
TOLERANCE
VOLTAGE (V)*
PART
period allows the µP to perform its initialization process.
(%)
A normal watchdog timeout period (t ) applies when-
WD
IN1
5.0
5.0
5.0
3.3
3.3
3.3
3.3
3.3
Adj
5.0
5.0
5.0
3.3
3.3
3.3
3.3
3.3
Adj
IN2
3.3
3.3
3.3
2.5
2.5
2.5
2.5
1.8
Adj
3.3
3.3
3.3
2.5
2.5
2.5
2.5
1.8
Adj
IN3
2.5
2.5
1.8
1.8
1.8
1.5
Adj
Adj
Adj
2.5
2.5
1.8
1.8
1.8
1.5
Adj
Adj
Adj
IN4
1.8
Adj
Adj
1.5
Adj
Adj
Adj
Adj
Adj
1.8
Adj
Adj
1.5
Adj
Adj
Adj
Adj
Adj
ever WDI transitions from high to low after the initial
watchdog timeout period occurs. WDI monitors the tog-
gling output of the µP, indicating normal processor
behavior. If WDI does not toggle during the normal
MAX6888AETE
MAX6888BETE
MAX6888CETE
MAX6888DETE
MAX6888EETE
MAX6888FETE
MAX6888GETE
MAX6888HETE
MAX6888QETE
MAX6888IETE
MAX6888JETE
MAX6888KETE
MAX6888LETE
MAX6888METE
MAX6888NETE
MAX6888OETE
MAX6888PETE
MAX6888RETE
5
5
5
watchdog timeout period (t
), indicating that the
5
WD
processor has stopped operating or is stuck in an infinite
execution loop, WDO goes low. WDO stays low until the
next transition on WDI. An initial watchdog timeout peri-
5
5
5
od (t ) starts when WDO goes high.
WDI
5
If WDO is connected to MR, the WDO will assert for a
short duration (~5µs), long enough to assert the RESET
output. Asserting RESET clears the watchdog timer and
WDO goes high. The reset output will remain asserted
for its timeout period after a watchdog fault. The watch-
dog timer stays cleared as long as RESET is low.
5
10
10
10
10
10
10
10
10
10
Applications Information
Layout and Bypassing
For better noise immunity, bypass each of the voltage-
detector inputs to GND with 0.1µF capacitors installed
as close to the device as possible. Bypass V
and BP
CC
to GND with 1µF capacitors installed as close to the
device as possible. V (when not externally supplied)
CC
*See thresholds options tables (Tables 1 and 2) for actual under-
and BP are internally generated voltages and should
not be used to supply power to external circuitry.
voltage and overvoltage thresholds.
Chip Information
PROCESS: BiCMOS
______________________________________________________________________________________ 11
Hex/Quad, Power-Supply Supervisory Circuits
Pin Configurations
TOP VIEW
12
11
10
9
12
11
10
9
IN4
13
13
14
15
16
IN4
8
7
6
5
I.C.
8
7
6
5
I.C.
IN3 14
IN3
IN2
WDI
WDI
MAX6888
MAX6887
15
IN2
MARGIN
MR
MARGIN
MR
16
IN1
*EXPOSED PAD
*EXPOSED PAD
IN1
1
2
3
4
1
2
3
4
THIN QFN
THIN QFN
*EXPOSED PAD CONNECTED TO GND.
*EXPOSED PAD CONNECTED TO GND.
Typical Operating Circuit
12V
5V
12V
DC-DC
1
DC-DC
2
3.3V
2.5V
DC-DC
3
DC-DC
1.8V
4
1.5V
1.2V
IN1
IN2
IN3
IN4
IN5*
IN6*
V
CC
LOGIC INPUT
OV
V
CC
WDO
LOGIC INPUT
µP
RESET
WDI
BP
RESET
MAX6887
MAX6888
LOGIC OUTPUT
GND
MARGIN
MR
GND
*MAX6887 ONLY
12 ______________________________________________________________________________________
Hex/Quad, Power-Supply Supervisory Circuits
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.)
______________________________________________________________________________________ 13
Hex/Quad, Power-Supply Supervisory Circuits
Package Information (continued)
(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.)
Revision History
Pages changed at Rev 1: 1, 5, 14
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.
14 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2007 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products, Inc.
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