MAX16056–MAX16059 125nA Supervisory Circuits with Capacitor- Adjustable Reset and Watchdog Timeouts General Description

MAX16056–MAX16059 125nA Supervisory Circuits with Capacitor- Adjustable Reset and Watchdog Timeouts General Description
MAX16056–MAX16059
125nA Supervisory Circuits with CapacitorAdjustable Reset and Watchdog Timeouts
General Description
Features
The MAX16056–MAX16059 are ultra-low-current 125nA
(typ) microprocessor (µP) supervisory circuits that monitor a single system supply voltage. These devices
assert an active-low reset signal whenever the V CC
supply voltage drops below the factory-trimmed reset
threshold, manual reset is pulled low, or the watchdog
timer runs out (MAX16056/MAX16058). The reset output
remains asserted for an adjustable reset timeout period
after V CC rises above the reset threshold. Factorytrimmed reset threshold voltages are offered from
1.575V to 4.625V in approximately 100mV increments
(see Table 1).
o Ultra-Low 125nA (typ) Supply Current
o 1.1V to 5.5V Operating Supply Range
o Factory-Set Reset Threshold Options from 1.575V
to 4.625V in Approximately 100mV Increments
o Capacitor-Adjustable Reset Timeout
o Capacitor-Adjustable Watchdog Timeout
(MAX16056/MAX16058)
o Watchdog Timer Capacitor Open Detect Function
o Optional Watchdog Disable Function
(MAX16056/MAX16058)
o Manual Reset Input
o Guaranteed RESET Valid for VCC ≥ 1.1V
o Push-Pull or Open-Drain RESET Output Options
o Power-Supply Transient Immunity
o Small, 3mm x 3mm TDFN Package
These devices feature adjustable reset and watchdog
timeout using external capacitors. The MAX16056/
MAX16058 contain a watchdog timer with a watchdog
select input (WDS) that multiplies the watchdog timeout
period by 128. The MAX16057/MAX16059 do not have
the watchdog feature.
The MAX16056–MAX16059 are available in either pushpull or open-drain output-type configurations (see the
Ordering Information). These devices are fully specified
over the -40°C to +125°C automotive temperature range.
The MAX16056/MAX16058 are available in the 8-pin
TDFN package, and the MAX16057/MAX16059 are available in the 6-pin TDFN package.
Applications
Portable/Battery-Powered Equipment
PDAs/Cell Phones
MP3 Players/Pagers
Glucose Monitors/Patient Monitors
Metering/HVAC
Typical Operating Circuit appears at end of data sheet.
Ordering Information
PINPACKAGE
PART
MAX16056ATA_ _+T 8 TDFN-EP*
MAX16057ATT_ _+T
6 TDFN-EP*
RESET
OUTPUT
WATCHDOG
TIMER
Push-Pull
Yes
Push-Pull
No
MAX16058ATA_ _+T 8 TDFN-EP*
Open-Drain
Yes
MAX16059ATT_ _+T
Open-Drain
No
6 TDFN-EP*
Note: All devices are specified over the -40°C to +125°C operating temperature range.
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
*EP = Exposed pad.
“_ _” represents the two number suffix needed when ordering
the reset threshold voltage value (see Table 1).
Standard versions and their package top marks are shown in
Table 3 at the end of data sheet.
Pin Configurations
TOP VIEW
VCC
WDS
WDI
SRT
VCC
N.C.
SRT
8
7
6
5
6
5
4
MAX16056
MAX16058
MAX16057
MAX16059
EP
1
2
RESET GND
EP
3
4
1
2
3
SWT
MR
RESET
GND
MR
TDFN
*CONNECT EXPOSED PAD TO GND.
TDFN
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
19-4686; Rev 2; 4/13
MAX16056–MAX16059
125nA Supervisory Circuits with CapacitorAdjustable Reset and Watchdog Timeouts
ABSOLUTE MAXIMUM RATINGS
Junction-to-Ambient Thermal Resistance (θJA) (Note 1)
6-Pin TDFN ...................................................................42°C/W
8-Pin TDFN ...................................................................41°C/W
Junction-to-Case Thermal Resistance (θJC) (Note 1)
6-Pin TDFN .....................................................................9°C/W
8-Pin TDFN .....................................................................8°C/W
Operating Temperature Range .........................-40°C to +125°C
Storage Temperature Range .............................-65°C to +150°C
Junction Temperature .....................................................+150°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) .......................................+260°C
VCC to GND ..............................................................-0.3V to +6V
SRT, SWT, WDS, MR, WDI, to GND ...........-0.3V to (VCC + 0.3V)
RESET (Push-Pull) to GND .........................-0.3V to (VCC + 0.3V)
RESET (Open-Drain) to GND ...................................-0.3V to +6V
Input Current (all pins) .................................................... ±20mA
Output Current (RESET) ................................................. ±20mA
Continuous Power Dissipation (TA = +70°C)
6-Pin TDFN (derate 23.8mW/°C above +70°C) .........1905mW
8-Pin TDFN (derate 24.4mW/°C above +70°C) .........1951mW
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer
board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
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
(VCC = 1.2V to 5.5V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = 3.3V, TA = +25°C.) (Note 2)
PARAMETER
Supply Voltage
Supply Current
SYMBOL
VCC
ICC
CONDITIONS
MIN
Hysteresis
VTH
VHYST
5.5
TA = -40°C to 0°C
1.2
5.5
VCC > VTH + 150mV,
no load, reset output
deasserted (Note 3)
VCC = 5.0V, TA =
-40°C to +85°C
142
210
VCC = 3.3V, TA =
-40°C to +85°C
132
185
VCC = 1.8V, TA =
-40°C to +85°C
125
175
VCC = 5.0V, TA =
-40°C to +125°C
142
430
VCC = 3.3V, TA =
-40°C to +125°C
132
415
VCC = 1.8V, TA =
-40°C to +125°C
125
400
VCC falling (see Table 1)
UNITS
V
nA
7
15
TA = +25°C
VTH 1.5%
VTH +
1.5%
TA = -40°C to
+125°C
VTH 2.5%
VTH +
2.5%
µA
V
VCC rising
0.5
%
80
µs
VCC to Reset Delay
tRD
VCC falling from (VTH + 100mV) to
(VTH - 100mV) at 10mV/µs
Reset Timeout Period
tRP
CSRT = 2700pF (Note 4)
2
MAX
1.1
VCC < VTH, no load, reset output asserted
VCC Reset Threshold
TYP
TA = 0°C to +125°C
10.5
14.18
17.0
ms
Maxim Integrated
MAX16056–MAX16059
125nA Supervisory Circuits with CapacitorAdjustable Reset and Watchdog Timeouts
ELECTRICAL CHARACTERISTICS (continued)
(VCC = 1.2V to 5.5V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = 3.3V, TA = +25°C.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
SRT Ramp Current
IRAMP1
TA = -40°C to
VSRT = 0V to VRAMP1, +125°C
VCC = 1.6V to 5V
TA = +25°C
SRT Ramp Threshold
VRAMP1
VCC = 1.6V to 5V (VRAMP rising)
Watchdog Timeout Clock Period
SWT Ramp Current
SWT Ramp Threshold
tWDPER
IRAMP2
VRAMP2
VOL
TA = +25°C
TA = -40°C to +125°C
TA = -40°C to
VSWT = 0V to VRAMP2, +125°C
VCC = 1.6V to 5V
TA = +25°C
VCC = 1.6V to 5V (VRAMP2 rising)
MIN
TYP
MAX
197
240
282
210
240
270
1.173
1.235
1.297
5
6.4
8
3.5
6.4
9.5
197
240
282
210
240
270
1.173
1.235
1.297
0.3
VCC ≥ 2.7V, ISINK = 1.2mA
0.3
VCC ≥ 4.5V, ISINK = 3.2mA
VOH
RESET Output-Leakage Current,
Open Drain
ILKG
MAX16056/MAX16057
0.8 x
VCC
VCC ≥ 2.25V,
ISOURCE = 500µA
0.8 x
VCC
VCC ≥ 4.5V,
ISOURCE = 800µA
0.8 x
VCC
1.0
0.7 x
VCC
tMPW
µs
200
tMRD
ns
250
WDI Minimum Pulse Width
(Note 5)
150
Input Leakage Current
MR, WDI, WDS is connected to GND or VCC
-100
Note 2:
Note 3:
Note 4:
Note 5:
µA
V
1
MR Glitch Rejection
MR to RESET Delay
V
0.3 x
VCC
VIL
MR Minimum Pulse Width
ms
V
VCC > VTH, reset not asserted, VRESET =
5.5V (MAX16058/MAX16059)
Input-Logic Levels
V
0.4
VCC ≥ 1.8V,
ISOURCE = 200µA
VIH
nA
nA
VCC ≥ 1.0V, ISINK = 50µA
RESET Output Voltage
UNITS
ns
ns
+100
nA
Devices are production tested at TA = +25°C. Specifications over temperature limits are guaranteed by design.
WDI input period is 1s with tRISE and tFALL < 50ns.
Worst case of SRT ramp current and voltage is used to guarantee minimum and maximum limits.
Guaranteed by design, not production tested.
Maxim Integrated
3
MAX16056–MAX16059
125nA Supervisory Circuits with CapacitorAdjustable Reset and Watchdog Timeouts
Typical Operating Characteristics
(VCC = 2.5V, TA = +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
TA = -40NC
TA = +25NC
1.4
200
150
1.2
1.0
0.8
0.6
100
0.1
MAX16056 toc03
1.6
VCC = 3.3V
50
VCC = 1.8V
0.4
0.2
0
0
0
50
100
150
200
250
300
-40 -25 -10 5 20 35 50 65 80 95 110 125
VCC (V)
TEMPERATURE (NC)
CSRT (nF)
NORMALIZED RESET TIMEOUT PERIOD
vs. TEMPERATURE
NORMALIZED WATCHDOG
TIMEOUT PERIOD vs. TEMPERATURE
MAXIMUM VCC TRANSIENT DURATION
vs. RESET THRESHOLD OVERDRIVE
1.03
1.02
1.00
0.98
1.02
1.01
1.00
0.99
0.96
0.98
0.94
0.97
0.92
0.96
0.90
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (NC)
TEMPERATURE (NC)
VCC FALLING FROM VTH + 100mV
10
100
1000
VCC TO RESET DELAY
vs. TEMPERATURE
MAX16056 toc07
120
VCC = VTH + 100mV TO VTH - 100mV
110
1.010
100
1.005
tRD (Fs)
NORMALIZED VTH
10
RESET THRESHOLD OVERDRIVE (mV)
NORMALIZED RESET THRESHOLD
VOLTAGE vs. TEMPERATURE
1.015
RESET OCCURS ABOVE THIS LINE
100
1
0.95
-40 -25 -10 5 20 35 50 65 80 95 110 125
1.020
1000
MAX16056 toc08
NORMALIZED tWD
1.04
1.04
TRANSIENT DURATION (Fs)
1.06
MAX16056 toc05
1.05
MAX16056 toc04
1.08
MAX16056 toc06
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
1.10
NORMALIZED tRP
1.8
VCC = 5.5V
250
VCC = 2.5V
1.000
0.995
90
80
70
0.990
60
0.985
50
0.980
4
2.0
MAX16056 toc02
300
RESET IS NOT ASSERTED
VTH = 1.575V
tRP (s)
1.0
TA = +85NC
350
SUPPLY CURRENT (nA)
ICC (FA)
VTH = 2.23V
MAX16056 toc01
10.0
TA = +125NC
RESET TIMEOUT PERIOD
vs. CSRT
SUPPLY CURRENT vs. TEMPERATURE
-40 -25 -10 5 20 35 50 65 80 95 110 125
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (NC)
TEMPERATURE (NC)
Maxim Integrated
MAX16056–MAX16059
125nA Supervisory Circuits with CapacitorAdjustable Reset and Watchdog Timeouts
Typical Operating Characteristics (continued)
(VCC = 2.5V, TA = +25°C, unless otherwise noted.)
RESET OUTPUT-LOW VOLTAGE
vs. SINK CURRENT
VCC = 1.8V
0.15
0.10
VCC = 3.3V
0.05
0
1.0
0.40
0.9
0.8
0.35
0.30
VCC = 1.8V
0.25
0.20
VCC = 3.3V
0.15
VCC = 2.5V
0.10
0.7
0.6
0.5
0.4
0.3
0.2
0.05
0.1
0
0
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
0
ISINK (mA)
MAX16056 toc11
0.45
SUPPLY CURRENT (FA)
VOL (V)
0.20
SUPPLY CURRENT vs. WATCHDOG
SWITCHING FREQUENCY
MAX16056 toc10
VCC = 2.5V
0.50
OUTPUT-HIGH VOLTAGE (VCC-VOH) (V)
0.25
MAX16056 toc09
0.30
RESET OUTPUT-HIGH VOLTAGE
vs. SOURCE CURRENT
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
0.01
ISOURCE (mA)
0.1
1
10
1000 10,000
100
WATCHDOG SWITCHING FREQUENCY (kHz)
MANUAL RESET DELAY
vs. TEMPERATURE
MANUAL RESET DELAY
MAX16056 toc13
MAX16056 toc12
270
268
266
MR
1V/div
tMRD (ns)
264
262
260
RESET
1V/div
258
256
254
252
250
-40 -25 -10 5 20 35 50 65 80 95 110 125
200ns/div
TEMPERATURE (NC)
RESET SOURCE CAPABILITY
vs. SUPPLY VOLTAGE
RESET SINK CAPABILITY
vs. SUPPLY VOLTAGE
VRESET = 0.8 x VCC
3.5
SOURCE CURRENT (mA)
SINK CURRENT (mA)
8
7
6
5
4
3
2
MAX16056 toc15
VRESET = 0.3V
9
4.0
MAX16056 toc14
10
3.0
2.5
2.0
1.5
1.0
0.5
1
0
0
0
0.5
1.0
1.5
2.0
VCC (V)
2.5
3.0
3.5
4.0
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VCC (V)
Maxim
Integrated
_______________________________________________________________________________________________________
55
MAX16056–MAX16059
125nA Supervisory Circuits with CapacitorAdjustable Reset and Watchdog Timeouts
Pin Description
PIN
MAX16056/
MAX16058
MAX16057/
MAX16059
NAME
FUNCTION
Push-Pull or Open-Drain Reset Output. RESET asserts whenever VCC drops below the
selected reset threshold voltage (VTH) or manual reset is pulled low. RESET remains low
for the reset timeout period after all reset conditions are deasserted, and then goes high.
The watchdog timer triggers a reset pulse (tRP) whenever a watchdog fault occurs
(MAX16056/MAX16058).
1
1
RESET
2
2
GND
Ground
3
—
SWT
Watchdog Timeout Input. Connect a capacitor between SWT and GND to set the basic
watchdog timeout period (tWD). Determine the period by the formula tWD = Floor[CSWT x
5.15 x 106/6.4ms] x 6.4ms + 3.2ms (Note 6) with tWD in seconds and CSWT in Farads, or
use Table 2. Extend the basic watchdog timeout period by using the WDS input. Connect
SWT to ground to disable the watchdog timer function. The value of the capacitor must be
between 2275pF and 0.54µF to have a valid watchdog timeout period.
4
3
MR
Manual-Reset Input. Drive MR low to manually reset the device. RESET remains asserted
for the reset timeout period after MR is released. There is no internal pullup on MR. MR
must not be left unconnected. Connect MR to VCC if not used.
SRT
Reset Timeout Input. Connect a capacitor from SRT to GND to select the reset timeout
period. Determine the period as follows: tRP = 5.15 x 106 x CSRT with tRP in seconds and
CSRT in Farads, or use Table 2. The value of the capacitor must be between 39pF and
4.7µF.
WDI
Watchdog Input. A falling transition must occur on WDI within the selected watchdog
timeout period or a reset pulse occurs. The watchdog timer clears when a falling transition
occurs on WDI or whenever RESET is asserted. Connect SWT to ground to disable the
watchdog timer function.
5
6
4
—
7
—
WDS
Watchdog Select Input. WDS selects the watchdog timeout mode. Connect WDS to
ground to select normal mode. The watchdog timeout period is tWD. Connect WDS to VCC
to select extended mode, multiplying the basic timeout period (tWD) by a factor of 128. A
change in the state of WDS clears the watchdog timer.
8
6
VCC
Supply Voltage. VCC is the power-supply input and the input for fixed threshold VCC
monitor. For noisy systems, bypass VCC with a 0.1µF capacitor to GND.
—
5
N.C.
—
—
EP
No Connection. Not internally connected.
Exposed Pad. Connect EP to GND or leave unconnected.
Note 6: Floor: take the integral value.
6
Maxim Integrated
MAX16056–MAX16059
125nA Supervisory Circuits with CapacitorAdjustable Reset and Watchdog Timeouts
Detailed Description
The MAX16056–MAX16059 are ultra-low-current 125nA
(typ) µP supervisory circuits that monitor a single system supply voltage. These devices assert an active-low
reset signal whenever the VCC supply voltage drops
below the factory-trimmed reset threshold, manual
reset is pulled low, or the watchdog timer runs out
(MAX16056/MAX16058). The reset output remains
asserted for an adjustable reset timeout period after
VCC rises above the reset threshold. The reset and
watchdog delay periods are adjustable using external
capacitors.
RESET Output
The MAX16056–MAX16059 µP supervisory circuits assert
a reset to prevent code-execution errors during powerup, power-down, and brownout conditions. The reset
output is guaranteed to be valid for VCC down to 1.1V.
When VCC falls below the reset threshold, the RESET
output asserts low. Once VCC exceeds the reset threshold plus the hysteresis, an internal timer keeps the reset
output asserted for the capacitor-adjusted reset timeout
period (tRP), then after this interval the reset output
deasserts (see Figure 1). The reset function features
immunity to power-supply voltage transients.
Manual-Reset Input (MR)
Many µP-based products require manual-reset capability, allowing the operator, a test technician, or external
logic circuitry to initiate a reset. The MAX16056–
MAX16059 feature an MR input. A logic-low on MR
asserts a reset. RESET remains asserted while MR is
low and for the timeout period, tRP, after MR returns
high. Connect MR to VCC if unused. MR can be driven
with CMOS logic levels or with open-drain/collector outputs (with a pullup resistor). Connect a normally open
momentary switch from MR to GND and a resistor from
MR to VCC to implement a manual-reset function; external debounce circuitry is not required. If MR is driven
by long cables or the device is used in a noisy environment, connect a 0.1µF capacitor from MR to GND to
provide additional noise immunity.
Maxim Integrated
Watchdog Timer
The MAX16056/MAX16058’s watchdog timer circuitry
monitors the µP’s activity. If the µP does not toggle
(high-to-low) the watchdog input (WDI) within the
capacitor-adjustable watchdog timeout period (tWD),
RESET asserts for the reset timeout period (tRP). The
internal watchdog timer is cleared by: 1) any event that
asserts RESET, by 2) a falling transition at WDI (that
can detect pulses as short as 150ns) or by 3) a transition (high-to-low or low-to-high) at WDS. While reset is
asserted, the watchdog timer remains cleared and
does not count. As soon as reset deasserts, the watchdog timer resumes counting.
There are two modes of watchdog operation, normal
mode and extended mode. In normal mode (Figure 2),
the watchdog timeout period is determined by the
value of the capacitor connected between SWT and
ground. In extended mode (Figure 3), the watchdog
timeout period is multiplied by 128. For example, in
extended mode, a 0.33µF capacitor gives a watchdog
timeout period of 217s (see Table 2). To disable the
watchdog timer function, connect SWT to ground.
When VCC ramps above VTH + VHYST, the value of the
external SWT capacitor is sampled after RESET goes
high. When sampling is finished, the capacitor value is
stored in the device and is used to set watchdog timeout. If RESET goes low before sampling is finished, the
device interrupts sampling, and sampling is restarted
when RESET goes high again.
If the external SWT capacitor is less than 470pF, the
sampling result sets the watchdog timeout to zero. This
causes the watchdog to assert RESET continuously
after sampling is finished. If a PCB manufacturing
defect caused the connection to CSWT to be broken,
the capacitance is very low and RESET is continuously
asserted. If the external SWT capacitor is greater than
0.47µF, the sampling result sets the watchdog timeout
to be infinite, disabling the watchdog function.
7
MAX16056–MAX16059
125nA Supervisory Circuits with CapacitorAdjustable Reset and Watchdog Timeouts
VTH + VHYST
VTH
VCC
tRP
tRP
tMRD
tRD
RESET
tMPW
MR
Figure 1. RESET Timing Relationship
VCC
tRP
tWD
WDI
0V
VCC
RESET
0V
NORMAL MODE (WDS = GND)
Figure 2. Watchdog Timing Diagram, Normal Mode, WDS = GND
VCC
tWD x 128
WDI
0V
VCC
tRP
RESET
0V
EXTENDED MODE (WDS = VCC)
Figure 3. Watchdog Timing Diagram, Extended Mode, WDS = VCC
8
Maxim Integrated
MAX16056–MAX16059
125nA Supervisory Circuits with CapacitorAdjustable Reset and Watchdog Timeouts
Applications Information
Selecting the Reset Timeout Capacitor
The reset timeout period is adjustable to accommodate
a variety of µP applications. To adjust the reset timeout
period (tRP), connect a capacitor (CSRT) between SRT
and ground. The reset timeout capacitor is calculated
as follows:
CSRT = tRP/(5.15 x 106)
with tRP in seconds and CSRT in Farads.
CSRT must be a low-leakage (< 10nA) type capacitor. A
ceramic capacitor with low temperature coefficient
dielectric (i.e., X7R) is recommended.
Selecting Watchdog Timeout Capacitor
The watchdog timeout period is adjustable to accommodate a variety of µP applications. With this feature,
the watchdog timeout can be optimized for software
execution. The programmer can determine how often
the watchdog timer should be serviced. Adjust the
watchdog timeout period (tWD) by connecting a capacitor (CSWT) between SWT and GND. For normal mode
operation, calculate the watchdog timeout as follows:
tWD = Floor[CSWT x 5.15 x 106/6.4ms] x 6.4ms + 3.2ms
with tWD in seconds and CSWT in Farads.
(Floor: take the integral value) (Figures 2 and 3)
The maximum tWD is 296s. If the capacitor sets tWD
greater than the 296s, tWD = infinite and the watchdog
timer is disabled.
CSWT must be a low-leakage (< 10nA) type capacitor.
A ceramic capacitor with low temperature coefficient
dielectric (i.e., X7R) is recommended.
Watchdog Timeout Accuracy
The watchdog timeout period is affected by the SWT
ramp current (IRAMP2) accuracy, the SWT ramp threshold (VRAMP2) and the watchdog timeout clock period
(tWDPER). In the equation above, the constant 5.15 x
106 is equal to VRAMP2/IRAMP2, and 6.4ms equals the
watchdog timeout clock period. Calculate the timeout
Maxim Integrated
accuracy by substituting the minimum, typical, and
maximum values into the equation.
For example, if CSWT = 100nF.
tWDMIN = Floor[100 x 10-9 x 1.173/(282 x 10-9)/9.5ms] x
3.5ms + 0.5 x 3.2ms = 141.7ms
tWDNOM = Floor[100 x 10-9 x 1.235/(240 x 10-9)/6.4ms]
x 6.4ms + 0.5 x 6.4ms = 515.2ms
tWDMAX = Floor[100 x 10-9 x 1.297/(197 x 10-9)/3.5ms]
x 9.5ms + 0.5 x 9.5ms = 1790.75ms
Transient Immunity
For applications with higher slew rates on VCC during
power-up, additional bypass capacitance may be
required.
The MAX16056–MAX16059 are relatively immune to
short-duration supply voltage transients, or glitches on
VCC. The Maximum VCC Transient Duration vs. Reset
Threshold Overdrive graph in the Typical Operating
Characteristics shows this transient immunity. The area
below the curve of the graph is the region where these
devices typically do not generate a reset pulse. This
graph was generated using a falling pulse applied to
VCC, starting 100mV above the actual reset threshold
(VTH) and ending below this threshold (reset threshold
overdrive). As the magnitude of the transient increases,
the maximum allowable pulse width decreases.
Typically, a 100mV VCC transient duration of 40µs or
less does not cause a reset.
Using the MAX16056–MAX16059 for
Reducing System Power Consumption
Using the RESET output to control an external p-channel
MOSFET to control the on-time of a power supply can
result in lower system power consumption in systems that
can be regularly put to sleep. By tying the WDI input to
ground, the RESET output becomes a low-frequency
clock output. When RESET is low, the MOSFET is turned
on and power is applied to the system. When RESET is
high, the MOSFET is turned off and no power is consumed by the system. This effectively reduces the shutdown current of the system to zero (Figure 4).
9
MAX16056–MAX16059
125nA Supervisory Circuits with CapacitorAdjustable Reset and Watchdog Timeouts
BAT
1MΩ
0.1μF
0.1μF
VCC
VCC1
RESET
μP
MAX16056
MR
WDI
MANUAL
POWER-ON
SRT
SWT
CSWT
GND
WDS
CSRT
VCC
RESET
VCC1
tRP
tWD
tRP
Figure 4. Using MAX16056–MAX16059 to Reduce System Power Consumption
10
Maxim Integrated
MAX16056–MAX16059
125nA Supervisory Circuits with CapacitorAdjustable Reset and Watchdog Timeouts
Interfacing to Other Voltages
for Logic Compatibility
The open-drain RESET output can be used to interface
to a µP with other logic levels. The open-drain output is
connected to a voltage from 0V to 5.5V as shown in
Figure 5. Generally, the pullup resistor connected to
RESET connects to the supply voltage that is being
monitored at the device’s VCC input. However, some
systems use the open-drain output to level-shift from
the supervisor’s monitored supply to another supply
voltage. As the supervisor’s VCC decreases, so does
the device’s ability to sink current at RESET.
Ensuring a Valid RESET Down to VCC = 0V
(Push-Pull RESET)
When VCC falls below 1.1V, the current-sinking capability of RESET decreases drastically. The high-impedance CMOS logic inputs connected to RESET can drift
to undetermined voltages. This presents no problems in
most applications, since most µPs and other circuitry
do not operate with VCC below 1.1V. In those applications where RESET must be valid down to 0, add a pulldown resistor between the MAX16056/MAX16057
push-pull RESET output and GND. The resistor sinks
any stray leakage currents, holding RESET low (Figure
6). Choose a pulldown resistor that accommodates
leakages, such that RESET is not significantly loaded
and is capable of pulling to GND. The external pulldown cannot be used with the open-drain RESET output of the MAX16058/MAX16059.
3.3V
5V
VCC
VCC
VCC
MAX16058
MAX16059
VCC
100kΩ
μP
RESET
MAX16056
MAX16057
RESET
RESET
2MΩ
GND
GND
Figure 5. Interfacing with Other Voltage Levels
Maxim Integrated
GND
Figure 6. Ensuring RESET Valid to VCC = GND
11
MAX16056–MAX16059
125nA Supervisory Circuits with CapacitorAdjustable Reset and Watchdog Timeouts
Table 1. Threshold Suffix Guide
SUFFIX
12
VCC THRESHOLD FALLING (V)
MIN
TYP
MAX
46
4.509
4.625
4.741
45
4.388
4.500
4.613
44
4.266
4.375
4.484
43
4.193
4.300
4.408
42
4.095
4.200
4.305
41
3.998
4.100
4.203
40
3.900
4.000
4.100
39
3.802
3.900
3.998
38
3.705
3.800
3.895
37
3.608
3.700
3.793
36
3.510
3.600
3.690
35
3.413
3.500
3.588
34
3.315
3.400
3.485
33
3.218
3.300
3.383
32
3.120
3.200
3.280
31
2.998
3.075
3.152
30
2.925
3.000
3.075
29
2.852
2.925
2.998
28
2.730
2.800
2.870
27
2.633
2.700
2.768
26
2.559
2.625
2.691
25
2.438
2.500
2.563
24
2.340
2.400
2.460
23
2.255
2.313
2.371
225
2.180
2.235
2.290
22
2.133
2.188
2.243
21
2.048
2.100
2.153
20
1.950
2.000
2.050
19
1.853
1.900
1.948
18
1.755
1.800
1.845
17
1.623
1.665
1.707
16
1.536
1.575
1.614
Maxim Integrated
MAX16056–MAX16059
125nA Supervisory Circuits with CapacitorAdjustable Reset and Watchdog Timeouts
Table 2. Capacitor Selection Guide
CAPACITANCE (pF)
tRP (ms)
tWD (ms)
tWD x 128 (ms)
39
47
56
68
82
100
120
0
(no capacitor is connected)
150
180
220
270
330
Not recommended
390
470
560
680
820
1000
Indeterminate
(0, 9.6, or 16)
1200
Indeterminate
(0, 1228.8, or 1636)
1500
1800
2200
2700
14.18
16
1641
3300
16.99
16
1641
3900
20.1
22.4
2460
2460
4700
24.21
22.4
5600
28.84
28.8
3280
6800
35.00
35.2
4099
8200
42.23
41.6
4918
10,000
51.5
54.4
6556
12,000
61.8
60.8
7376
15,000
77.25
80
9833
18,000
92.7
92.8
11,472
Maxim Integrated
13
MAX16056–MAX16059
125nA Supervisory Circuits with CapacitorAdjustable Reset and Watchdog Timeouts
Table 2. Capacitor Selection Guide (continued)
CAPACITANCE (pF)
14
tRP (ms)
tWD (ms)
tWD x 128 (ms)
22,000
113.3
112
13,929
27,000
139.05
137.6
17,206
33,000
169.95
169.6
21,302
39,000
200.85
201.6
25,398
47,000
242.05
240
30,313
56,000
288.4
291.2
36,867
68,000
350.2
348.8
44,240
82,000
422.3
419.2
53,251
100,000
515
515.2
65,539
120,000
618
617.6
78,646
150,000
772.5
771.2
98,307
180,000
927
924.8
117,968
220,000
1133
1129.6
144,182
270,000
1390.5
1392
177,769
330,000
1699.5
1699.2
217,091
390,000
2008.5
2006.4
256,412
470,000
2420.5
2416
308,841
680,000
3502
820,000
4223
1,000,000
5150
1,500,000
7725
2,200,000
11,330
3,300,000
16,995
4,700,000
24,205
Indeterminate
(may be infinite and watchdog is disabled)
Infinite
(watchdog is disabled)
Maxim Integrated
MAX16056–MAX16059
125nA Supervisory Circuits with CapacitorAdjustable Reset and Watchdog Timeouts
Table 3. Standard Versions
Maxim Integrated
PART
TOP MARK
MAX16056ATA17+
BKZ
MAX16056ATA23+
BLA
MAX16056ATA26+
BLB
MAX16056ATA29+
BLC
MAX16056ATA31+
BLD
MAX16056ATA46+
BLE
MAX16057ATT17+
ATQ
MAX16057ATT23+
ATR
MAX16057ATT26+
ATS
MAX16057ATT29+
ATT
MAX16057ATT31+
AUC
MAX16057ATT46+
AUD
MAX16058ATA16+
BLF
MAX16058ATA22+
BLG
MAX16058ATA26+
BLH
MAX16058ATA29+
BLI
MAX16058ATA31+
BLJ
MAX16058ATA44+
BLK
MAX16059ATT16+
ATW
MAX16059ATT22+
ATX
MAX16059ATT26+
ATY
MAX16059ATT29+
ATZ
MAX16059ATT31+
AUA
MAX16059ATT44+
AUB
15
MAX16056–MAX16059
125nA Supervisory Circuits with CapacitorAdjustable Reset and Watchdog Timeouts
Typical Operating Circuit
BAT
1MΩ
0.1μF
VCC
VCC
RESET
MAX16056
MR
μP
WDI
MANUAL
RESET
SRT
SWT
CSWT
GND
CSRT
Package Information
Chip Information
PROCESS: BiCMOS
16
WDS
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a
“+”, “#”, or “-” in the package code indicates RoHS status only.
Package drawings may show a different suffix character, but the
drawing pertains to the package regardless of RoHS status.
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
8 TDFN-EP
T833-2
21-0137
90-0059
6 TDFN-EP
T633-2
21-0137
90-0058
Maxim Integrated
MAX16056–MAX16059
125nA Supervisory Circuits with CapacitorAdjustable Reset and Watchdog Timeouts
Revision History
REVISION
NUMBER
REVISION
DATE
0
6/09
DESCRIPTION
Initial release
PAGES
CHANGED
—
1
6/10
Updated Absolute Maximum Ratings, Electrical Characteristics, and Table 3.
2
4/13
Removed Automotive Infotainment from Applications sections
2, 3, 15
1
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent
licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and
max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000 ________________________________ 17
© 2013 Maxim Integrated Products, Inc.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
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