|
|
PDF MAX696 Data sheet ( Hoja de datos )
| Número de pieza | MAX696 | |
| Descripción | Microprocessor Supervisory Circuits | |
| Fabricantes | Maxim Integrated | |
| Logotipo |  |
|
1. MAX696  Hay una vista previa y un enlace de descarga de MAX696 (archivo pdf) en la parte inferior de esta página. Total 16 Páginas | ||
|
No Preview Available !
MAX696/MAX697
Microprocessor Supervisory Circuits
General Description
The MAX696/MAX697 supervisory circuits reduce the
complexity and number of components required for
power-supply monitoring and battery-control functions
in microprocessor (μP) systems. These include μP reset
and backup-battery switchover, watchdog timer, CMOS
RAM write protection, and power-failure warning. The
MAX696/MAX697 significantly improve system reliability
and accuracy compared to that obtained with separate
ICs or discrete components.
The MAX696 and MAX697 are supplied in 16-pin pack-
ages and perform six functions:
1) A reset output during power-up, power-down, and
brownout conditions. The threshold for this “lowline”
reset is adjustable by an external voltagedivider.
2) A reset pulse if the optional watchdog timer has not
been toggled within a specified time.
3) Individual outputs for low-line and watchdog fault con-
ditions.
4) The reset time may be left at its default value of 50ms,
or may be varied with an external capacitor or clock
pulses.
5) A separate 1.3V threshold detector for power-fail warn-
ing, low-battery detection, or to monitor a power supply
other than VCC.
The MAX696 also has battery-backup switching for CMOS
RAM, CMOS microprocessor, or other lowpower logic.
The MAX697 lacks battery-backup switching, but has
write-protection pins (CE IN and CE OUT) for CMOS
RAM or EPROM. In addition, it consumes less than 250
microamperes.
Applications
●● Computers
●● Controllers
●● Intelligent Instruments
●● Critical μP Power Monitoring
Typical Operating Circuit appears at end of data sheet.
Pin Configurations continued at end of data sheet.
Features
●● Adjustable Low-Line Monitor and Power-Down Reset
●● Power-OK/Reset Time Delay
●● Watchdog Timer—100ms, 1.6s, or Adjustable
●● Minimum Component Count
●● 1μA Standby Current
●● Battery-Backup Power Switching (MAX696)
●● On-Board Gating of Chip-Enable Signals (MAX697)
●● Separate Monitor for Power-Fail or Low-Battery
Warning
Ordering Information
PART
MAX696C/D
MAX696CPE
MAX696CWE
MAX696EPE
MAX696EJE
MAX696EWE
MAX696MJE
TEMP RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
PIN-PACKAGE
Dice
16 PDIP
16 Wide SO
16 PDIP
16 CERDIP
16 Wide SO
16 CERDIP
Ordering Information continued at end of data sheet.
Devices in PDIP and SO packages are available in both leaded
and lead(Pb)-free packaging. Specify lead free by adding the +
symbol at the end of the part number when ordering. Lead free
not available for CERDIP package.
Pin Configurations
TOP VIEW
VBATT 1
VOUT 2
16 RESET
15 RESET
VCC 3
GND 4
MAX696
14 WDO
13 LLIN
BATT ON 5
12 N.C.
LOW LINE 6
11 WDI
OSC IN 7
10 PFO
OSC SEL 8
9 PFI
19-0829; Rev 5; 7/14
1 page  
MAX696/MAX697
Microprocessor Supervisory Circuits
Pin Description
PIN
MAX696
MAX697
1—
2—
33
45
5—
66
77
88
99
10 10
11 11
12 2
13 4
14 14
15 15
16 16
NAME
FUNCTION
VBATT
VOUT
VCC
GND
BATT ON
LOW LINE
OSC IN
OSC SEL
PFI
PFO
WDI
N.C.
LLIN
WDO
RESET
RESET
Backup-Battery Input. Connect to ground if a backup battery is not used.
The higher of VCC or VBATT is internally switched to VOUT. Connect VOUT to VCC if
VOUT and VBATT are not used.
+5V Input
0V Ground Reference for All Signals
BATT ON goes High when VOUT is Internally Switched to the VBATT Input. It goes
low when VOUT is internally switched to VCC. The output typically sinks 7mA and
can directly drive the base of an external pnp transistor to increase the output current
above the 50mA rating of VOUT.
LOW LINE goes Low when LLIN Falls Below 1.3V. It returns high as soon as LLIN
rises above 1.3V. See Figure 5.
OSC IN Sets the Reset Delay Timing and Watchdog Timeout Period when OSC SEL
Floats or is Driven Low. The timing can also be adjusted by connecting an external
capacitor to this pin. See Figure 7. When OSC SEL is high, OSC IN selects between
fast and slow watchdog timeout periods
When OSC SEL is Unconnected or Driven High, the Internal Oscillator Sets the
Reset Time Delay and Watchdog Timeout Period. When OSC SEL is low, the
external oscillator input, OSC IN, is enabled. OSC SEL has a 3µA internal pullup. See
Table 1.
PFI is the Noninverting Input to the Power-Fail Comparator. When PFI is less than
1.3V, PFO goes low. Connect PFI to GND or VOUT when not used. See Figure 1.
PFO is the Output of the Power-Fail Comparator. It goes low when PFI is less than
1.3V. The comparator is turned off and PFO goes low when VCC is below VBATT.
The Watchdog Input, WDI, is a Three-Level Input. If WDI remains either high or low
for longer than the watchdog timeout period, RESET pulses low and WDO goes low.
The watchdog timer is disabled when WDI is left floating or is driven to mid-supply.
The timer resets with each transition at the watchdog timer input.
No Connection. Leave this pin open.
Low-Line Input. LLIN is the CMOS input to a comparator whose other input is a
precision 1.3V reference. The output is LOW LINE and is also connected to the reset
pulse generator. See Figure 2.
The Watchdog Output, WDO, goes Low if WDI Remains either High or Low for
Longer than the Watchdog Timeout Period. WDO is set high by the next transition at
WDI. If WDI is unconnected or at mid-supply, WDO remains high. WDO also goes
high when LOW LINE goes low.
RESET goes Low whenever LLIN Falls Below 1.3V or VCC Falls Below the VBATT
Input Voltage. RESET remains low for 50ms after LLIN goes above 1.3V. RESET also
goes low for 50ms if the watchdog timer is enabled but not serviced within its timeout
period. The RESET pulse width can be adjusted as shown in Table 1.
RESET is an Active-High Output. It is the inverse of RESET.
www.maximintegrated.com
Maxim Integrated │ 5
5 Page 
MAX696/MAX697
Microprocessor Supervisory Circuits
WATCHDOG INPUT
VCC 2.7V
+
-
+
-
1.0V
TRANSITION
DETECTOR
FOR EACH TRANSITION
LOW LINE
(HI IF LLIN < 1.3V)
HI IF WATCHDOG
INPUT IS FLOATING
PRESCALER
Q6
10.24kHz FROM INTERNAL OSCILLATOR
OR EXTERNALLY SET FREQUENCY FROM
OSC IN PIN
WATCHDOG TIMEOUT SELECT
RESET
COUNTER
R Q10/12
WATCHDOG
COUNTER
Q11
Q13
R Q15
WATCHDOG
TIMEOUT
SELECTOR
LOGIC
GOES HIGH AT THE
END OF WATCHDOG
TIMEOUT PERIOD
SR
RESET
FLIP FLOP
QQ
SQ
RS
LONG/SHORT
FF
R
LOW
LINE
WATCHDOG
FAULT FF
Q
RESET RESET
WATCHDOG OUTPUT
Figure 6. Watchdog Timer Block Diagram
a reset is issued. The normal timeout period becomes
effective following the first transition of WDI after RESET
has gone high. The watchdog timer is restarted at the end
of reset, whether the reset was caused by lack of activ-
ity on WDI or by LLIN falling below 1.3V. If WDI remains
either high or low, reset pulses will be issued every 1.6s.
The watchdog monitor can be deactivated by floating the
watchdog input (WDI).
The watchdog output (WDO) goes low if the watchdog
timer times out, and it remains low until set high by the
next transition on the watchdog input. WDO is also set
high when LLIN goes below 1.3V. The watchdog timeout
period defaults to 1.6s and the reset pulse width defaults
to 50ms. The MAX696 and MAX697 allow these times to
be adjusted per Table 1.
The internal oscillator is enabled when OSC SEL is high
or floating. In this mode, OSC IN selects between the
1.6s and 100ms watchdog timeout periods. In either case,
immediately after a reset, the timeout period is 1.6s. This
gives the microprocessor time to reinitialize the system.
WD transmissions while RESET is low are ignored. If OSC
IN is low, then the 100ms watchdog period becomes effec-
tive after the first transition of WDI. The software should
be written so the I/O port driving WDI is left in its power-up
reset state until the initialization routines are completed
and the microprocessor is able to toggle WDI at the mini-
mum 70ms watchdog timeout period.
www.maximintegrated.com
Maxim Integrated │ 11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet MAX696.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| MAX690 | Microprocessor Supervisory Circuits | Maxim Integrated |
| MAX690 | I2C-Compatible RTC in a TDFN | Maxim Integrated |
| MAX690 | Microprocessor Supervisory Circuits | Maxim Integrated |
| MAX6900 | I2C-Compatible RTC in a TDFN | Maxim Integrated |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |