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PDF MAX16028 Data sheet ( Hoja de datos )
| Número de pieza | MAX16028 | |
| Descripción | Sequencing/Supervisory Circuits | |
| Fabricantes | Maxim Integrated Products | |
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19-0525; Rev 1; 6/06
Dual-/Triple-/Quad-Voltage, Capacitor-
Adjustable, Sequencing/Supervisory Circuits
General Description
The MAX16025–MAX16030 are dual-/triple-/quad-volt-
age monitors and sequencers that are offered in a
small TQFN package. These devices offer enormous
design flexibility as they allow fixed and adjustable
thresholds to be selected through logic inputs and pro-
vide sequence timing through small external capaci-
tors. These versatile devices are ideal for use in a wide
variety of multivoltage applications.
wwwA.DsattahSeheveotl4taUg.ceomat each monitored input exceeds its
respective threshold, its corresponding output goes
high after a propagation delay or a capacitor-set time
delay. When a voltage falls below its threshold, its
respective output goes low after a propagation delay.
Each detector circuit also includes its own enable input,
allowing the power-good outputs to be shut off inde-
pendently. The independent output for each detector is
available with push-pull or open-drain configuration
with the open-drain version capable of supporting volt-
ages up to 28V, thereby allowing them to interface to
shutdown and enable inputs of various DC-DC regula-
tors. Each detector can operate independently as four
separate supervisory circuits or can be daisy-chained
to provide controlled power-supply sequencing.
The MAX16025–MAX16030 also include a reset func-
tion that deasserts only after all of the independently
monitored voltages exceed their threshold. The reset
timeout is internally fixed or can be adjusted externally.
These devices are offered in a 4mm x 4mm TQFN
package and are fully specified from -40°C to +125°C.
Applications
Multivoltage Systems
DC-DC Supplies
Servers/Workstations
Storage Systems
Networking/Telecommunication Equipment
Selector Guide
PART
MAX16025
MAX16026
MAX16027
MAX16028
MAX16029
MAX16030
MONITORED
VOLTAGES
2
2
3
3
4
4
INDEPENDENT
OUTPUTS
2 (Open-drain)
2 (Push-pull)
3 (Open-drain)
3 (Push-pull)
4 (Open-drain)
4 (Push-pull)
RESET
OUTPUT
Open-drain
Push-pull
Open-drain
Push-pull
Open-drain
Push-pull
Features
o 2.2V to 28V Operating Voltage Range
o Fixed Thresholds for 3.3V, 2.5V, 1.8V, 1.5V, and
1.2V Systems
o 1.5% Accurate Adjustable Threshold Monitors
Voltages Down to 0.5V
o 2.7% Accurate Fixed Thresholds Over
Temperature
o Fixed (140ms min)/Capacitor-Adjustable Delay
Timing
o Independent Open-Drain/Push-Pull Outputs
o Enable Inputs for Each Monitored Voltage
o 9 Logic-Selectable Threshold Options
o Manual Reset and Tolerance Select (5%/10%) Inputs
o Small, 4mm x 4mm TQFN Package
o Fully Specified from -40°C to +125°C
Ordering Information
PART*
TEMP RANGE
PIN-
PACKAGE
PKG
CODE
MAX16025TE+ -40°C to +125°C 16 TQFN T1644-4
MAX16026TE+ -40°C to +125°C 16 TQFN T1644-4
MAX16027TP+ -40°C to +125°C 20 TQFN T2044-3
MAX16028TP+
MAX16029TG+
-40°C to +125°C 20 TQFN
-40°C to +125°C 24 TQFN
T2044-3
T2444-4
MAX16030TG+ -40°C to +125°C 24 TQFN T2444-4
+Denotes lead-free package.
*For tape and reel, add a “T” after the “+.” All tape and reel
orders are available in 2.5k increments.
Pin Configurations
TOP VIEW
18 17 16 15 14 13
MR 19
12 TH1
CRESET 20
11 EN4
CDLY4 21
CDLY3 22
CDLY2 23
MAX16029
MAX16030
10 EN3
9 EN2
8 EN1
CDLY1 24
7 GND
+1 2 3 4 5 6
THIN QFN
(4mm x 4mm)
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  
Dual-/Triple-/Quad-Voltage, Capacitor-
Adjustable, Sequencing/Supervisory Circuits
Typical Operating Characteristics (continued)
(VCC = 3.3V, TA = +25°C, unless otherwise noted.)
RESET OUTPUT LOW VOLTAGE
vs. SINK CURRENT
1.0
0.9
0.8
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0.6
0.5
0.4
0.3
0.2
0.1
0
0123456
SINK CURRENT (mA)
7
RESET OUTPUT HIGH VOLTAGE
vs. SOURCE CURRENT
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
0
PUSH-PULL VERSIONS
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
SOURCE CURRENT (mA)
ENABLE TURN-ON
MAX16025 toc13
CRESET = VCC
CDLY_ = OPEN
EN_
RESET TIMEOUT DELAY
MAX16025 toc14
CRESET = VCC
CDLY_ = OPEN
IN_
ENABLE TURN-OFF
MAX16025 toc12
CRESET = VCC
CDLY_ = OPEN
EN_
4µs/div
OUT_
RESET
MR FALLING vs. RESET
MAX16025 toc15
CRESET = VCC
CDLY_ = OPEN
MR
OUT_
RESET
OUT_
RESET
RESET
40ms/div
100ms/div
4µs/div
MR RISING vs. RESET
MAX16025 toc16
CRESET = VCC
CDLY_ = OPEN
MR
RESET
40ms/div
MAXIMUM TRANSIENT DURATION
vs. THRESHOLD OVERDRIVE
100
90 OUTPUT ASSERTED ABOVE THIS LINE
80
70
60
50
40
30
20
10
0
1 10 100 1000
THRESHOLD OVERDRIVE (mV)
_______________________________________________________________________________________ 5
5 Page 
Dual-/Triple-/Quad-Voltage, Capacitor-
Adjustable, Sequencing/Supervisory Circuits
Calculate the reset timeout period as follows:
tRP
=
VTH−RESET
ICH−RESET
× CCRESET
+ 30 × 10−6
where VTH-RESET is 0.5V, ICH-RESET is 0.5µA, tRP is in
seconds, and CCRESET is in Farads. To ensure timing
accuracy and proper operation, minimize leakage at
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Adjustable Delay (CDLY_)
When VIN rises above VTH with EN_ high, the internal
250nA current source begins charging an external
capacitor connected from CDLY_ to GND. When the
voltage at CDLY_ reaches 1V, OUT_ goes high. When
OUT_ goes high, CDLY_ is immediately held low.
Adjust the delay (tDELAY) from when VIN rises above
VTH (with EN_ high) to OUT_ going high according to
the equation:
tDELAY
=
VTH−CDLY
ICH−CDLY
× CCDLY
+ 35 × 10−6
where VTH-CDLY is 1V, ICH-CDLY is 0.25µA, CCDLY is in
Farads, tDELAY is in seconds, and tDELAY+ is the inter-
nal propagation delay of the device. To ensure timing
accuracy and proper operation, minimize leakage
at CDLY.
Manual-Reset Input (MR)
Many µP-based products require manual-reset capabil-
ity, allowing the operator, a test technician, or external
logic circuitry to initiate a reset. A logic-low on MR
asserts RESET low. RESET remains asserted while MR
is low and during the reset timeout period (140ms fixed
or capacitor adjustable) after MR returns high. The MR
input has a 500nA internal pullup, so it can be left
unconnected, if not used. MR can be driven with TTL or
CMOS logic levels, or with open-drain/collector outputs.
Connect a normally open momentary switch from MR to
GND to create a manual-reset function. External
debounce circuitry is not required. If MR is driven from
long cables or if the device is used in a noisy environ-
ment, connect a 0.1µF capacitor from MR to GND to
provide additional noise immunity.
Pullup Resistor Values
The exact value of the pullup resistors for the open-
drain outputs is not critical, but some consideration
should be made to ensure the proper logic levels
when the device is sinking current. For example, if
VCC = 2.25V and the pullup voltage is 28V, keep the
sink current less than 0.5mA as shown in the Electrical
Characteristics table. As a result, the pullup resistor
should be greater than 56kΩ. For a 12V pullup, the
resistor should be larger than 24kΩ. Note that the ability
to sink current is dependent on the VCC supply voltage.
Power-Supply Bypassing
The device operates with a VCC supply voltage from
2.2V to 28V. When VCC falls below the UVLO threshold,
all the outputs go low and stay low until VCC falls below
1.2V. For noisy systems or fast rising transients on VCC,
connect a 0.1µF ceramic capacitor from VCC to GND
as close to the device as possible to provide better
noise and transient immunity.
Ensuring Valid Output with VCC Down to
0V (MAX16026/MAX16028/MAX16030 Only)
When VCC falls below 1.2V, the ability for the output to
sink current decreases. In order to ensure a valid out-
put as VCC falls to 0V, connect a 100kΩ resistor from
OUT/RESET to GND.
Typical Application Circuits
Figures 4 and 5 show typical applications for the
MAX16025–MAX16030. In high-power applications,
using an n-channel device reduces the loss across the
MOSFETs as it offers a lower drain-to-source on-resis-
tance. However, an n-channel MOSFET requires a suffi-
cient VGS voltage to fully enhance it for a low RDS_ON.
The application in Figure 4 shows the MAX16027 con-
figured in a multiple-output sequencing application.
Figure 5 shows the MAX16029 in a power-supply
sequencing application using n-channel MOSFETs.
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 15 Páginas | |
| PDF Descargar | [ Datasheet MAX16028.PDF ] | |
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