Precision Power Supply Voltage Monitor
— 5 V, 3.3 V and 3 V systems
— Five threshold voltage options
„ Active High or Low Reset
— Valid reset guaranteed at VCC = 1 V
„ 400 kHz I
2
C Bus
„ 2.7 V to 5.5 V Operation
„ Low power CMOS technology
„ 16-Byte Page Write Buffer
„ Built-in inadvertent write protection
— WP pin (CAT1025)
„ 1,000,000 Program/Erase cycles
„ Manual Reset Input
„ 100 year data retention
„ Industrial and extended temperature ranges
„ Green packages available with NiPdAu Lead
finished
For Ordering Information details, see page 19.
DESCRIPTION
The CAT1024 and CAT1025 are complete memory
and supervisory solutions for microcontroller-based
systems. A 2k-bit serial EEPROM memory and a
system power supervisor with brown-out protection
are integrated together in low power CMOS techno–
logy. Memory interface is via a 400 kHz I
2
C bus.
The CAT1025 provides a precision VCC sense circuit
and two open drain outputs: one (RESET) drives high
and the other (RESET ¯¯¯¯¯¯) drives low whenever VCC falls
below the reset threshold voltage. The CAT1025 also
has a Write Protect input (WP). Write operations are
disabled if WP is connected to a logic high.
The CAT1024 also provides a precision VCC sense
circuit, but has only a RESET ¯¯¯¯¯¯ output and does not
have a Write Protect input.
The power supply monitor and reset circuit protect
memory and system controllers during power up/down
and against brownout conditions. Five reset threshold
voltages support 5 V, 3.3 V and 3 V systems. If power
supply voltages are out of tolerance reset signals
become active, preventing the system microcontroller,
ASIC or peripherals from operating. Reset signals
become inactive typically 200 ms after the supply
voltage exceeds the reset threshold level. With both
active high and low reset signals, interface to
microcontrollers and other ICs is simple. In addition,
the RESET ¯¯¯¯¯¯ pin or a separate input, MR ¯¯¯, can be used
as an input for push-button manual reset capability.
The CAT1024/25 memory features a 16-byte page. In
addition, hardware data protection is provided by a
VCC sense circuit that prevents writes to memory
whenever VCC falls below the reset threshold or until
VCC reaches the reset threshold during power up.
Available packages include an 8-pin PDIP and a
surface mount 8-pin SO, 8-pin TSSOP, 8-pin TDFN
and 8-pin MSOP packages. The TDFN package thick
ness is 0.8 mm maximum. TDFN footprint is 3 x 3 mm
