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PDF MAX6894 Data sheet ( Hoja de datos )
| Número de pieza | MAX6894 | |
| Descripción | (MAX6892 - MAX6894) Power-Supply Sequencers/Supervisors | |
| Fabricantes | Maxim Integrated Products | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de MAX6894 (archivo pdf) en la parte inferior de esta página. Total 19 Páginas | ||
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19-3596; Rev 0; 2/05
Pin-Selectable, Octal/Hex/Quad, Power-Supply
Sequencers/Supervisors
General Description
The MAX6892/MAX6893/MAX6894 pin-selectable, mul-
tivoltage supply sequencers/supervisors monitor sever-
al voltage-detector inputs and one watchdog input,
asserting the respective voltage detector or watchdog
output when the inputs drop below the configured volt-
age thresholds or the watchdog timer expires. The
MAX6892 features eight voltage detector inputs and 10
outputs. The MAX6893 features six voltage-detector
inputs and eight outputs, while the MAX6894 features
four voltage detector inputs and six outputs. A RESET
output ensures all monitored inputs are above the set
thresholds. The voltage detector outputs are configured
as open drain. Manual reset and margin disable inputs
offer additional flexibility.
The thresholds of the MAX6892/MAX6893/MAX6894 are
selected through five logic inputs (TH0–TH4). The logic on
these five inputs selects the supply voltage tolerance (5%
or 10%) and one of 32 factory-set thresholds settings.
Watchdog and reset timeout periods can use factory
default settings or are independently adjustable by con-
necting external capacitors.
When any of the monitored voltages falls below its
threshold, the respective output asserts and remains
asserted for 6.25ms (typ) after the monitored voltage
exceeds the threshold. The outputs can be connected
to the shutdown or enable inputs of DC-DC regulators
to provide turn-on power sequencing to ensure proper
system initialization.
The MAX6892 is available in a 5mm x 5mm x 0.8mm,
32-pin, thin QFN package, while the MAX6893/
www.DMatAaSXh6e8e9t44U.acroemavailable in a 5mm x 5mm x 0.8mm, 28-
pin, thin QFN package. The MAX6892/MAX6893/
MAX6894 are specified to operate over the extended
temperature range (-40°C to +85°C)
Applications
Telecommunication/Central Office Systems
Networking Systems
Servers/Workstations
Base Stations
Storage Equipment
Multimicroprocessor/Voltage Systems
Typical Operating Circuit appears at end of data sheet.
Features
♦ Pin-Selectable or User-Adjustable Voltage
Detector Thresholds
♦ Dedicated RESET and WDO Outputs
♦ Capacitor-Adjustable Reset and Watchdog
Timeout Periods
♦ Factory-Default Reset and Watchdog Timeout
Periods
♦ Up to Eight Independent, Open-Drain Power-Good
Outputs
♦ Enable Margining Disable and Manual Reset
Controls
♦ -40°C to +85°C Operating Temperature Range
♦ Small 5mm x 5mm Thin QFN Package
♦ Few External Components
♦ ±1% Threshold Accuracy
Ordering Information
PART
MAX6892ETJ
MAX6893ETI
MAX6894ETI
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-
PACKAGE
32 Thin QFN
28 Thin QFN
28 Thin QFN
PKG
CODE
T3255-4
T2855-8
T2855-8
Pin Configurations
TOP VIEW
32 31 30 29 28 27 26 25
PG2 1
PG3 2
PG4 3
GND 4
PG5 5
PG6 6
PG7 7
PG8 8
MAX6892
*EXPOSED PADDLE
24 IN7
23 IN8
22 DBP
21 VCC
20 ENABLE
19 SRT
18 SWT
17 TH4
9 10 11 12 13 14 15 16
THIN QFN
*EXPOSED PAD INTERNALLY CONNECTED TO GND.
Pin Configurations 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.
1 page  
Pin-Selectable, Octal/Hex/Quad, Power-Supply
Sequencers/Supervisors
Typical Operating Characteristics
(VIN1 = VIN6–VIN8 = GND, VIN2–VIN5 = 2.7V to 5.5V, WDI = GND, TH0–TH4 = MARGIN = MR = DBP. Typical values are at TA = +25°C.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE (IN2–IN5)
1.1
1.0
0.9 TA = +85°C
0.8
TA = +25°C
0.7 TA = -40°C
0.6
0.5
2.5
3.0 3.5 4.0 4.5 5.0
SUPPLY VOLTAGE (V)
5.5
IN_TO PG_ PROPAGATION DELAY
vs. TEMPERATURE
30
100mV OVERDRIVE
28
26
24
22
20
18
16
www.DataS14heet4U.com
12
10
-40
-15 10 35 60
TEMPERATURE (°C)
85
NORMALIZED DEFAULT WATCHDOG
TIMEOUT PERIOD vs. TEMPERATURE
1.04
1.03
1.02
1.01
1.00
0.99
0.98
0.97
0.96
-40
tRP = 1.6s
VSWT = VCC
-15 10 35 60
TEMPERATURE (°C)
85
SUPPLY CURRENT
vs. SUPPLY VOLTAGE (VCC)
1.1
1.0
0.9
TA = +85°C
0.8
0.7
TA = +25°C
TA = -40°C
0.6
0.5
2.5
3.0 3.5 4.0 4.5 5.0
SUPPLY VOLTAGE (V)
5.5
NORMALIZED DEFAULT RESET
TIMEOUT PERIOD vs. TEMPERATURE
1.020
1.015
1.010
1.005
1.000
0.995
0.990
0.985
0.980
-40
tRP = 200ms
VSRT = VCC
-15 10 35 60
TEMPERATURE (°C)
85
NORMALIZED ADJUSTABLE WATCHDOG
TIMEOUT PERIOD vs. TEMPERATURE
1.20
1.15
1.10
1.05
1.00
0.95
0.90
0.85
0.80
-40
tRP = 1.6s
CSWT = 0.33µF
-15 10 35 60
TEMPERATURE (°C)
85
NORMALIZED PG_ TIMEOUT PERIOD
vs. TEMPERATURE
1.3
1.2
1.1
1.0
0.9
0.8
0.7
-40
-15 10 35 60
TEMPERATURE (°C)
85
NORMALIZED ADJUSTABLE RESET
TIMEOUT PERIOD vs. TEMPERATURE
1.10
1.08
1.06
1.04
1.02
1.00
0.98
0.96
0.94 tRP = 200ms
0.92 CSRT = 47nF
0.90
-40
-15 10 35 60
TEMPERATURE (°C)
85
1.005
1.004
1.003
1.002
1.001
1.000
0.999
0.998
0.997
0.996
0.995
-40
NORMALIZED IN_ THRESHOLD
vs. TEMPERATURE
-15 10 35 60
TEMPERATURE (°C)
85
_______________________________________________________________________________________ 5
5 Page 
Pin-Selectable, Octal/Hex/Quad, Power-Supply
Sequencers/Supervisors
Detailed Description
The MAX6892/MAX6893/MAX6894 pin-selectable, mul-
tivoltage supply sequencers/supervisors monitor sever-
al voltage detector inputs and one watchdog input,
asserting the outputs when the respective input thresh-
olds have been reached or a timeout occurs. All ver-
sions have an enable manual reset and margin input
disable. The MAX6892/MAX6893/MAX6894 voltage
thresholds are selected by logic inputs and/or an exter-
nal voltage-divider. A RESET output ensures all moni-
tored inputs are above the pin-selected/adjustable
thresholds. Watchdog and reset timeout periods can
use factory default settings or are independently
adjustable by connecting external capacitors. In addi-
tion, all devices can be powered through the voltage
detector inputs alone, or externally supplied from a
constant supply on the VCC pin (see the Powering the
MAX6892/MAX6893/MAX6894 section). The outputs
are factory configured as open drain.
Powering the
MAX6892/MAX6893/MAX6894
The MAX6892/MAX6893/MAX6894 derive power from
the voltage detector inputs: IN2–IN5 (MAX6892/
MAX6893), IN2–IN4 (MAX6894), or through an external-
ly supplied VCC. A virtual diode-ORing scheme selects
the positive input that supplies power to the device
(see the Functional Diagram). The highest input voltage
on IN2–IN5 (MAX6892/MAX6893)/IN2–IN4 (MAX6894)
supplies power to the device. One of IN2–IN5
(MAX6889/MAX6890)/IN2–IN4 (MAX6891) or VCC must
be at least 2.7V to ensure proper operation.
www.DataSheet4U.com
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.
VCC powers the analog circuitry and is the bypass con-
nection for the MAX6892/MAX6893/MAX6894 internal
supply. Bypass VCC to GND with a 1µF ceramic capac-
itor installed as close to the device as possible. The
internal supply voltage, measured at VCC, equals the
maximum of IN2–IN5. If VCC is externally supplied, VCC
must be at least 200mV higher than any voltage
applied to IN2–IN5 and VCC must be brought up first.
VCC always powers the device when all IN_ are factory
set as “ADJ.” Do not use the internally generated VCC
to provide power to external circuitry.
The MAX6892/MAX6893/MAX6894 also generate a dig-
ital supply voltage (DBP) for the internal logic circuitry
and the output stages. Bypass DBP to GND with a 1µF
ceramic capacitor installed as close to the device as
possible. The nominal DBP output voltage is 2.55V. Do
not use DBP to provide power to external circuitry.
Inputs
The MAX6892/MAX6893/MAX6894 contain multiple
logic and voltage detector inputs. Each voltage detec-
tor input is monitored for undervoltage thresholds.
Voltage Detector Inputs (IN_)
The MAX6892/MAX6893/MAX6894 offer several moni-
tor options with both pin-selectable and adjustable
reset thresholds. The threshold voltage at each
adjustable IN_ input is typically 0.6V. To monitor a volt-
age >0.6V, connect a resistor-divider network to the
circuit as shown in Figure 1:
VIN_TH = VTH (R1 + R2) / R2 (Equation 1)
where VIN_TH is the desired reset threshold voltage for
the respective IN_ and VTH is the input threshold
(0.6V).
Resistors R1 and R2 can have high values to minimize
current consumption due to low-leakage currents. Set
R2 to some conveniently high value (10kΩ, for exam-
ple) and calculate R1 based on the desired reset
threshold voltage, using the following formula:
R1 = R2 x (VIN_TH/VTH - 1)
VIN_TH
R1 VCC
IN_ MAX6892 VCC
MAX6893
R2 MAX6894
GND
VIN_TH = 0.6 x (R1 + R2) / R2
Figure 1. Adjusting the Monitored Threshold
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 19 Páginas | |
| PDF Descargar | [ Datasheet MAX6894.PDF ] | |
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