MAXIM MAX6877, MAX6878, MAX6879 User Manual

General Description
The MAX6877/MAX6878/MAX6879 multivoltage power trackers/sequencers/supervisors monitor up to three system voltages and provide proper power-up and power-down control for systems requiring voltage track­ing or sequencing. These devices ensure controlled voltage tracking within a specified range or sequencing in the proper order as system power supplies are enabled. The MAX6877/MAX6878/MAX6879 generate all required voltages and timing to control up to three external n-channel pass FETs for the OUT1/OUT2/ OUT3 supply voltages (see the Selector Guide for dif­ferent features of each device).
The MAX6877/MAX6878/MAX6879 feature adjustable undervoltage thresholds for each input supply. When all the voltages are above these adjustable thresholds, the devices turn on the external n-channel MOSFETs to either sequence or track the voltages to the system. During voltage-tracking mode, the voltage at the GATE of each MOSFET is increased to slowly bring up all supplies at a controlled slew rate. The MAX6877/ MAX6878/MAX6879 feature an autoretry or latch-off mode with capacitor-adjusted timing.
These devices also provide a controlled power-down (tracking mode) when the system shuts off in an orderly manner. When an unexpected fault occurs, the outputs are all pulled down simultaneously with an internal 100pulldown to help discharge capactive loads at the MOSFET’s source. The MAX6877/MAX6878/ MAX6879 feature independent internal charge pumps to fully enhance the external FETs for low-voltage drop at highpass current. The MAX6877 and MAX6878 also feature a power-good output with a selectable timeout period that can be used for system reset.
The MAX6877/MAX6878/MAX6879 are available in small 4mm x 4mm 24-pin and 16-pin thin QFN pack­ages and are fully specified over the -40°C to +85°C extended operating temperature range.
Applications
Multivoltage Systems
Networking Systems
Telecom
Storage Equipment
Servers/Workstations
Features
Pin-Selectable Tracking or Sequencing Control
for Up to Three Supply Voltages
Capacitor-Adjustable Power-Up/Down Tracking
Slew Rate
Capacitor-Adjustable Power-Up Sequencing DelayInternal Charge Pumps to Enhance External
n-Channel FETs
Capacitor-Adjustable Timeout Period Power-Good
Output (MAX6877/MAX6878)
Adjustable Undervoltage Lockout or
Logic-Enable Input
Internal 100Ω Pulldown for Each Output to
Discharge Capacitive Load Quickly
0.5V to 5.5V Nominal IN_/OUT_ Range2.7V to 5.5V Operating Voltage RangeImmune to Short Voltage TransientsSmall 4mm x 4mm 24-Pin or 16-Pin Thin QFN
Packages
MAX6877/MAX6878/MAX6879
Dual-/Triple-Voltage, Power-Supply
Trackers/Sequencers/Supervisors
________________________________________________________________ Maxim Integrated Products 1
Pin Configurations
Ordering Information
19-3771; Rev 0; 7/05
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.
Ordering Information continued at end of data sheet.
+Denotes lead-free package.
Selector Guide appears at end of data sheet.
Pin Configurations continued at end of data sheet.
查询MAX6877供应商
PART TEMP RANGE
MAX6877ETG+ -40°C to +85°C 24 Thin QFN T2444-4
MAX6877ETG -40°C to +85°C 24 Thin QFN T2444-4
PIN­PACKAGE
PKG
CODE
TOP VIEW
GATE2
19
OUT1
20
GATE1
21
22
IN3
IN2
23
24
IN1
*EXPOSED PADDLE CONNECTED TO GND.
GATE3
OUT2
1718 16 14 13
+
12
CC
V
ABP
4mm x 4mm THIN QFN
OUT3
15
MAX6877
EP*
456
3
SET3
FAULT
SET2
PG/RST
SET1
MARGIN
12
11
10
9
8
7
EN/UV
TRK/SEQ
LTCH/RTR
TIMEOUT
SLEW
DELAY
GND
MAX6877/MAX6878/MAX6879
Dual-/Triple-Voltage, Power-Supply Trackers/Sequencers/Supervisors
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VCC, IN1, IN2, or IN3 = +2.7V to +5.5V, EN/UV = MARGIN = ABP, TA= -40°C to +85°C, unless otherwise specified. Typical values are at T
A
= +25°C, unless otherwise noted.) (Note 1)
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.
IN1, IN2, IN3, VCC....................................................-0.3V to +6V
ABP
.....................................-0.3V to the highest of V
IN1
- V
IN3
or V
CC
SET1, SET2, SET3 ....................................................-0.3V to +6V
GATE1, GATE2, GATE3 .........................................-0.3V to +12V
OUT1, OUT2, OUT3 .................................................-0.3V to +6V
LTCH/RTR, TRK/SEQ, MARGIN ...............................-0.3V to +6V
FAULT, PG/RST, EN/UV ...........................................-0.3V to +6V
DELAY, SLEW, TIMEOUT .........................................-0.3V to +6V
OUT_ Current....................................................................±50mA
GND Current.....................................................................±50mA
Input/Output Current (all pins except
OUT_ and GND) ...........................................................±20mA
Continuous Power Dissipation (T
A
= +70°C) 16-Pin 4mm x 4mm Thin QFN
(derate 16.9mW/°C above +70°C).............................1349mW
24-Pin 4mm x 4mm Thin QFN
(derate 20.8mW/°C above +70°C).............................1667mW
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Maximum Junction Temperature .....................................+150°C
Lead Temperature (soldering, 10s) .................................+300°C
(All voltages referenced to GND, unless otherwise noted.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Operating Voltage Range V
Supply Current I
SET_ Threshold Range V
SET_ Threshold Hysteresis V
SET_ Input Current I
EN/UV Input Voltage
EN/UV Input Current I EN/UV Input Pulse Width t
DELAY, TIMEOUT Output Current I
DELAY, TIMEOUT Threshold Voltage
SLEW Output Current (Note 4) I
Track/Sequence Slew-Rate Timebase Accuracy
Timebase/C
S l ew - Rate Accur acy d ur i ng P ow er ­U p and P ow er - D ow n
Power-Good Threshold V
Ratio 100pF < C
SLEW
TH_HYS
V
V
CC
CC
TH
SET
EN_R
EN_F
EN
EN
D
S
SR C
TH_PG
Voltage on ABP (the highest of VCC or IN_) to ensure that PG/RST and FAULT are valid and GATE_ = 0V
Voltage on ABP (the highest of VCC or IN_) to ensure the device is fully operational
V
= 5.5V , IN 1 = IN 2 = IN 3 = 3.3V , no l oad 1.1 1.8 mA
C C
SET_ falling, TA = +25oC 0.4925 0.5 0.5075
SET_ falling, TA = -40oC to +85oC 0.4875 0.5 0.5125
SET_ rising 0.5 %
SET_ = 0.5V -100 +100 nA
Input rising 1.286
Input falling 1.22 1.25 1.28
EN/UV falling, 100mV overdrive 7 µs
(Notes 2, 3) 2.12 2.5 2.88 µA
= 3.3V 1.25 V
V
C C
= 200pF (Note 4) -15 +15 %
SLEW
C
= 200pF, ABP = 5.5V (Note 4) -50 +50 %
SLEW
V
falling 91.5 92.5 93.5 %
OUT_
< 1nF (Note 4) 104 k
SLEW
1.4
2.7 5.5
-5 +5 µA
22.5 25 27.5 µA
V
V
V
MAX6877/MAX6878/MAX6879
Dual-/Triple-Voltage, Power-Supply
Trackers/Sequencers/Supervisors
_______________________________________________________________________________________ 3
Note 1: Specifications guaranteed for the stated global conditions. 100% production tested at TA= +25°C and TA= +85°C.
Specifications at T
A
= -40°C to +85°C are guaranteed by design. These devices meet the parameters specified when at
least one of V
CC
, IN1/IN2/IN3 is between 2.7V to 5.5V, while the remaining IN1/IN2/IN3 are between 0 and 5.5V.
Note 2: A current I
D
= 2.5µA ±15% is generated internally and is used to set the DELAY and TIMEOUT periods and used as a refer-
ence for t
DELAY
and t
TIMEOUT
.
Note 3: The total DELAY is t
DELAY
= 200ms + (500kx C
DELAY
). Leave DELAY unconnected for 200µs delay. The total TIMEOUT is
t
TIMEOUT
= 200µs + (500kx C
TIMEOUT
). Leave TIMEOUT unconnected for 200µs timeout.
Note 4: A current I
S
= 25µA ±10% is generated internally and used as a reference for t
FAULT
, t
RETRY
, and slew rate.
Note 5: During power-up, only the condition OUT_ < ramp - V
TRK
is checked in order to stop the ramp. However, both conditions
OUT_ < ramp - V
TRK_F
and OUT_ > ramp + V
TRK_F
cause a fault. During power-down, only the condition OUT > ramp +
V
TRK
is checked in order to stop the ramp. However, both conditions OUT_ < ramp - V
TRK_F
and OUT_ > ramp + V
TRK_F
cause a fault (see Figure 10). Therefore, if OUT1, OUT2, and OUT3 (during power-up tracking and power-down) differ by more than 2 x V
TRK_F
, a fault condition is asserted.
Note 6: A 100pulldown to GND activated by a fault condition. See the Internal Pulldown section.
ELECTRICAL CHARACTERISTICS (continued)
(VCC, IN1, IN2, or IN3 = +2.7V to +5.5V, EN/UV = MARGIN = ABP, TA= -40°C to +85°C, unless otherwise specified. Typical values are at T
A
= +25°C, unless otherwise noted.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Power-Good Threshold Hysteresis V
GATE_ Output High V
GATE_ Pullup Current I
HYS_PGVOUT_
GOH
GUP
I
GD
GATE_ Pulldown Current
I
GDS
SET_ to GATE_ Delay t
FAULT, PG/RST Output Low V
Tracking Differential Voltage Stop Ramp
Tracking Differential Fault Voltage V
D-GATE
OL
V
TRK
TRK_F
Tracking Differential Voltage Hysteresis
Power-Low Threshold V
Power-Low Hysteresis V
TH_PL
TH_PLHYS
OUT to GND Pulldown Impedance V MARGIN, TRK/SEQ, LTCH/RTR
Pullup Current
MARGIN, TRK/SEQ, LTCH/RTR Input Voltage
I
IN
V
IL
V
IH
MARGIN, TRK/SEQ, LTCH/RTR Glitch Rejection
rising 0.5 %
I
SOURCE
= 0.5µA
During power-up and power-down, V
= 1V
GATE_
During power-up and power-down, V
= 5V
GATE_
When disabled, V
When disabled, V
GATE_
GATE_
= 5V, V
= 5V, V
IN_
IN_
IN_ +
4.2
2.5 4 µA
2.5 4 µA
2.7V 9.5
4V 20
IN_ +
5.0
IN_ +
5.8
V
mA
SET falling, 25mV overdrive 6 µs
V
IN_
V
IN_
2.7V, I
4.0V, I
= 1mA, output asserted 0.3
SINK
= 4mA, output asserted 0.4
SINK
V
Differential between each of the OUT_ and the ramp voltage during power-up and
75 125 180 mV
power-down, Figure 10 (Note 5)
Differential between each of the OUT_ and the ramp voltage, Figure 10 (Note 5)
200 250 310 mV
20 %
OUT_ falling 125 142 170 mV
OUT_ rising 10 mV
> 2.7V (Note 6) 100
ABP
7101A
0.8
2.0
V
100 ns
MAX6877/MAX6878/MAX6879
Dual-/Triple-Voltage, Power-Supply Trackers/Sequencers/Supervisors
4 _______________________________________________________________________________________
Figure 1. Tracking Timing Diagram in Normal Mode
EN/UV
V
EN_R
IN_
OUT_
EN/UV
IN1 = 2.5V
IN2 = 1.8V
IN3 = 0.7V
CAPACITOR­ADJUSTED SLEW RATE
t
DELAY
BUS VOLTAGE MONITORED THROUGH EN/UV INPUT
MONITORED THROUGH SET THRESHOLDS ON SET_ INPUTS
OUT1 = 2.5V
OUT2 = 1.8V
OUT3 = 0.7V
EN/UV
V
EN_F
PG/RST
t
TIMEOUT
MAX6877/MAX6878/MAX6879
Dual-/Triple-Voltage, Power-Supply
Trackers/Sequencers/Supervisors
_______________________________________________________________________________________ 5
Figure 2. Tracking in Fast Shutdown Mode
EN/UV
V
EN_R
PG/RST
IN_
OUT_
IN1 = 2.5V
IN2 = 1.8V
IN3 = 0.7V
CAPACITOR­ADJUSTED SLEW RATE
t
DELAY
t
TIMEOUT
BUS VOLTAGE MONITORED THROUGH EN/UV INPUT
MONITORED THROUGH SET THRESHOLDS ON SET_ INPUTS
OUT1 = 2.5V
OUT2 = 1.8V
OUT3 = 0.7V
EN/UV
V
EN_F
IN1 GOES BELOW SET1 THRESHOLD
FAULT = HIGH
FORCED INTO QUICK SHUTDOWN AFTER NORMAL SHUTDOWN WHEN IN1 GOES BELOW ITS SET VOLTAGE
MAX6877/MAX6878/MAX6879
Dual-/Triple-Voltage, Power-Supply Trackers/Sequencers/Supervisors
6 _______________________________________________________________________________________
Figure 3. Sequencing in Normal Mode
EN/UV
V
EN_R
IN1 = 2.5V
IN2 = 1.8V
IN_
OUT_
IN3 = 0.7V
CAPACITOR­ADJUSTED SLEW RATE
t
DELAY
BUS VOLTAGE MONITORED THROUGH EN/UV INPUT
MONITORED THROUGH SET THRESHOLDS ON SET_ INPUTS
OUT1 = 2.5V
OUT2 = 1.8V
OUT3 = 0.7V
t
t
DELAY
DELAY
EN/UV
V
EN_F
t
PG/RST
TIMEOUT
MAX6877/MAX6878/MAX6879
Dual-/Triple-Voltage, Power-Supply
Trackers/Sequencers/Supervisors
_______________________________________________________________________________________ 7
V
Figure 4. Sequencing in Fast Shutdown Mode
EN_R
IN_
EN/UV
EN/UV
BUS VOLTAGE MONITORED THROUGH EN/UV INPUT
IN1 = 2.5V
IN2 = 1.8V
IN3 = 0.7V
MONITORED THROUGH SET THRESHOLDS ON SET_ INPUTS
CAPACITOR­ADJUSTED SLEW RATE
OUT_
t
DELAY
PG/RST
FAULT
FORCED INTO QUICK SHUTDOWN WHEN OUT1 FALLS BELOW 92.5% of IN1
t
DELAY
OUT1 = 3.3V
t
DELAY
t
TIMEOUT
OUT2 = 1.8V
OUT3 = 0.7V
OUT_ FORCED BELOW V
TH_PG
MAX6877/MAX6878/MAX6879
Dual-/Triple-Voltage, Power-Supply Trackers/Sequencers/Supervisors
8 _______________________________________________________________________________________
Figure 5. Timing Diagram (Aborted Tracking)
EN/UV
V
EN_R
IN1 = 2.5V
IN2 = 1.8V
IN3 = 0.7V
IN_
CAPACITOR­ADJUSTED SLEW RATE
OUT_
t
PG/RST = LOW
DELAY
EN/UV
BUS VOLTAGE MONITORED THROUGH EN/UV INPUT
V
EN_F
MONITORED THROUGH SET THRESHOLDS ON SET_ INPUTS
OUT1 = 2.5V
OUT2 = 1.8V
OUT3 = 0.7V
*t
TIMEOUT
*ANY POWER-DOWN CONDITION BEFORE t
(PG/RST ASSERTED) CAUSES A SHUTDOWN.
TIMEOUT
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