November 2005 1 MIC2777
MIC2777 Micrel, Inc.
MIC2777
Dual Micro-Power Low Voltage Supervisor
General Description
The MIC2777 is a dual power supply supervisor that provides
under-voltage monitoring, manual reset capability, and power-
on reset generation in a compact 5-pin SOT package. Fea-
tures include two under-voltage detectors, one fixed and one
adjustable, and both active-high and active-low reset outputs.
One under-voltage detector compares V
DD
against a fixed
threshold. Ten factory-programmed thresholds are available.
The other under-voltage detector is user-adjustable.
The reset outputs are asserted for no less than 140ms at
power-on and any time V
DD
or the input voltage drops below
the corresponding reference voltage. They remain asserted
for the timeout period after the input voltage and V
DD
sub-
sequently rise back above the threshold boundaries. A reset
can be generated at any time by pulling down on the adjust-
able input. Hysteresis is included to prevent chattering due
to noise. Typical supply current is a low 3.5µA.
Typical Application
IN
R1
R2
/RST
VDD
RST
OTHER
LOGIC
MIC2777
MICROPROCESSOR
Manual
Reset
/RESET
V
CORE
V
CORE
1.0V
V
I/O
1.8V
V
I/O
GND
GND
Typical Application
Features
• Monitors two independent power supplies for under-volt-
age conditions
• One fixed and one user adjustable input
• 1.5% theshold accuracy
• Choice of factory-programmed thresholds
• User-adjustable input can monitor supplies as low as
0.3V
• Generates 140ms (minimum) power-on RESET pulse
• Manual reset capability
• Both active-high and active-low RESET outputs
• Input may be pulled above V
DD
(abs. max.)
• /RST output valid down to 1.2V
• Ultra-low supply current, 3.5µA typical
• Rejects brief input transients
• IttyBitty™ 5-pin SOT-23 package
Applications
• Monitoring processor, ASIC, or FPGA core and I/O volt-
ages
• Computer systems
• PDAs, hand-held PCs
• Embedded controllers
• Telecommunications systems
• Power supplies
• Wireless / Cellular systems
• Networking hardware
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
IttyBitty™ is a trademark of Micrel, Inc.
Ordering Information
Part Number
Junction Tem. Range
Package
Standard Marking Pb-Free Marking
MIC2777-XXBM5 UNXX MIC2777-XXYM5 UNXX –40ºC to +85ºC SOT-23-5