3-Pin µP Voltage Monitor
Preliminary
Circuit Description
Microprocessor Reset
The RESET pin is asserted whenever VCC falls below the
reset threshold voltage. The reset pin remains asserted for
a period of 240ms after VCC has risen above the reset
threshold voltage. The reset function ensures the micro-
processor is properly reset and powers up into a known
condition after a power failure. RESET will remain valid
with VCC as low as 1.4V.
RESET (ILC803, ILC809
RESET (ILC810)
3
VCC
+
-
Reset
Generator
2
Reset
Threshold (V)
1
GND
Figure 3: Block Diagram
VTH
VCC
Alternate Source Cross Reference Guide
Industry P/N
ILC Direct
Replacement
ILC803YU
ILC809JU
ILC809LU
tR
tR
MAX803XYUR-T
MAX809JEUR-T
MAX809LEUR-T
RESET
Figure 1: Timing Diagram
MAX809MEUR-T ILC809MU
MAX809REUR-T
MAX809SEUR-T
MAX809TEUR-T
MAX810JEUR-T
MAX810LEUR-T
ILC809RU
ILC809SU
ILC809TU
ILC810JU
ILC810LU
VCC Transients
The ILC803, ILC809 and ILC810 are relatively immune to
negative-going VCC glitches below the reset threshold.
Typically, a negative-going transient 125mV below the reset
threshold with a duration of 50µs (25µs for ILC8__R/S/T) or
less will not cause an unwanted reset.
MAX810MEUR-T ILC810MU
MAX810REUR-T
MAX810SEUR-T
MAX810TEUR-T
ILC810RU
ILC810SU
ILC810TU
Interfacing to Bi-directional Reset Pins
The ILC803/ILC809/ILC810 can interface with µPs with bi-
directional reset pins by connecting a 4.7kΩ resistor in
series with the ILC803/ILC809/ILC810 output and the mP
reset pin. ILC803 connects directly with a single pull-up
resistor (figure 2).
Device Markings Information
SC-70 Case
QJX
SOT-23 Case
QJXX
ILC803J
ILC803L
ILC803M
ILC803R
ILC803S
ILC803T
ILC809J
ILC809L
ILC809M
ILC809R
ILC809S
ILC809T
ILC810J
ILC810L
ILC810M
ILC810R
ILC810S
ILC810T
QLX
QMX
QRX
QSX
QTX
QLXX
QMXX
QRXX
QSXX
QTXX
VJXX
RESET Valid to 0V
A resistor can be added from the RESET pin to ground to
ensure the RESET output remains low with VCC down to
0V. A 100kΩ resistor connected from RESET to ground is
recommended. The size of the resistor should be large
enough to not load the RESET output and small enough to
pull-down any stray leakage currents.
VJX
VLX
VLXX
VMX
VRX
VSX
VTX
VMXX
VRXX
VSXX
VTXX
VCC
VCC
VCC
100K
ILC803
only
ZJX
ZJXX
ILC803
ILC809
ZCX
ZMX
ZRX
ZSX
ZCXX
ZMXX
ZRXX
ZSXX
µP
RESET
RESET
100K
ILC809
only
ZTX
ZTXX
Figure 2: Reset valid to VCC
Impala Linear Corporation
X-LOT CODE
XX-LOT CODE
www.impalalinear.com
(408) 574-3939
Sept 1999
3
ILC803/809/810 1.4
IMPALA [ Impala Linear Corporation ]
