MIC845
Micro-Power Comparator /
Battery Monitor
General Description
The MIC845 is a precision micro-power voltage
comparator with an on-chip 2.55V reference voltage
source.
Intended for voltage monitoring applications, the
MIC845 can be used with an external resistor divider
to detect a wide range of voltages, or without
external resistors to directly monitor voltages with its
high input impedance CMOS input.
The MIC845 incorporates a voltage reference and
comparator with fixed internal hysteresis. When the
2.55V internal threshold is crossed, the output
switches polarity.
MIC845 is available with a push-pull or open-drain
output stage. The push-pull output stage is
configured for both active high or active low output;
the open-drain output stage is only configured active
high.
Supply current is extremely low (typically 1µA),
making it ideal for portable applications.
MIC845 is supplied in Micrel’s Teeny™ 5-lead SC-
70 package.
Data sheets and support documentation can be
found on Micrel’s web site at www.micrel.com.
Teeny™
Features
•
•
•
•
Extremely low 1µA supply current (typical)
2.55V on chip reference
±2% voltage threshold accuracy
Optimized for PDAs, cellular telephones, pagers,
and other battery-powered devices
•
Open-drain output can be pulled up to 6V
regardless of supply voltage
•
5-lead SC-70 package
Applications
•
•
•
•
•
•
PDAs
Pagers
Cordless phones
Portable electronics
Motherboards
Bladed servers
____________________________________________________________________________________________________
Typical Applications
V
IN
V
DD
MIC845
3.3V
MIC845
V
DD
R1
OUT
GND
V
OUT
Memory
power
V
DD
INP
OUT
GND
to Host
INP
R2
V
REF
= 2.55V
2.75V < V
DD
< 5.5V
Lithium
Coin Cell
Threshold Detector with
Internal Fixed Hysteresis
Nano-Power Battery Monitor
Teeny™ is a trademark of Micrel, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
July 2005
M9999-070505
(408) 955-1690
Micrel, Inc.
MIC845
Ordering Information
Part Number
Standard
MIC845HBC5
MIC845LBC5
MIC845NBC5
Marking
B19
B20
B21
Pb-Free
MIC845HYC5
MIC845LYC5
MIC845NYC5
Marking*
B19
B20
B21
–40° to +85°C
–40° to +85°C
–40° to +85°C
SC-70
SC-70
SC-70
Temperature Range
Package
* Note:
Underscore on device marking indicates Pb-Free packaging.
Pin Configuration
INP GND NIC
1
3
2
4
OUT
5
VDD
SC-70-5 (C5)
(TOP VIEW)
Pin Description
Pin Number
1
2
3
4
Pin Name
NIC
GND
INP
OUT
(“N” Version)
OUT
(“H” Version)
OUT
(“L” Version)
5
VDD
Pin Function
No Internal Connection. A signal applied to this pin will have no effect
on device operation.
Ground
Input: Analog input to the comparator. When V
INP
> V
REF
+ V
HYST
, V
OUT
is
asserted, and the condition is held until V
INP
< V
REF
.
Output: Active-high, open-drain output. This output is low when
V
INP
< V
REF
, indicating a low voltage input. The output is high when
V
INP
> V
REF
+ V
HYST
.
Output: Active-high, Push-pull output. This output is low when
V
INP
< V
REF
, indicating a low voltage condition. The output is high when
V
INP
> V
REF
+ V
HYST
.
Output: Active-low, Push-pull output. This output is high when
V
INP
< V
REF
, indicating a low voltage condition. The output is low when
V
INP
> V
REF
+ V
HYST
.
Power Supply (Input): Independent supply input for internal circuitry.
July 2005
2
M9999-070505
(408) 955-1690
Micrel, Inc.
MIC845
Absolute Maximum Ratings
(1)
Supply Voltage (V
DD
) ..............................-0.3V to +6V
Input Voltage (V
INP
).................................-0.3V to +6V
Output Current (I
OUT
)......................................... 20mA
Junction Temperature (T
J
) .............. –40°C to +125°C
Storage Temperature (T
s
)............... –65°C to +150°C
Lead Temperature (soldering, 5 sec.) ..............260°C
ESD Rating
(3)
........................................................3kV
Operating Ratings
(2)
Supply voltage (V
DD
) ........................ +2.75V to +5.5V
Input Voltage............................................... -0.3 to 6V
Ambient Temperature (T
A
)................ –40°C to +85°C
Junction to Ambient Thermal Resistance:
SC-70 (θ
JA
) ............................................ 450°C/W
Electrical Characteristics
2.75V < V
DD
< 5.5V; T
A
= 25°C,
Bold
values indicate –40°C< T
A
< +85°C, unless noted.
Parameter
I
DD
I
INP
I
INP_PD
V
REF
V
HYST
V
OUT
V
OUT
Parameter
Supply Current
Input Leakage Current
Input Leakage Current in power down
V
REF
Comparator Hysteresis
Output Voltage, ‘N’
Output Voltage, ‘L’ and ‘H’
I
SINK
= 1.6mA, VDD
≥
2.75V
I
SINK
= 1.6mA, VDD
≥
2.75V
I
SOURCE
= 500µA,
VDD
≥
2.75V
t
D
Propagation Delay
V
INP
= 2.7V to 2.4V
V
INP
= 2.4V to 2.7V
Notes:
1. Exceeding the absolute maximum rating may damage the device.
2. The device is not guaranteed to function outside its operating rating.
3. Devices are ESD sensitive. Handling precautions recommended. Human body model: 1.5k in series with 100pF.
4. VDD is tied to Gnd, not left floating.
Conditions
No load on output
V
DD
= 5.5V, V
INP
= 0V
V
DD
= 0V
(note 4),
V
INP
= 5.5V
–40°C to 85°C
Min
Typ.
1
.005
.005
Max
3
10
10
2.60
40
0.3
0.3
Units
µA
nA
nA
V
mV
V
V
V
2.50
8
2.55
25
0.95
× V
DD
0.99
× V
DD
12
8
39
26
µs
µs
July 2005
3
M9999-070505
(408) 955-1690
Micrel, Inc.
MIC845
Typical Characteristics
I
DD
vs. Temperature
800
600
I
DD
(nA)
400
200
0
V
DD
= 4.5V
V
IN
= 0V
1500
1000
500
0
-500
-1000
V
DD
= 0V
V
IN
= 4.5V
-1500
80
-2000
-40 -20 0
20 40 60
TEMPERATURE (°C)
80
V
DD
= 4.5V
V
IN
= 0V
V
DD
= 0V
V
IN
= 4.5V
I
IN
vs. Temperature
-200
-40 -20 0
20 40 60
TEMPERATURE (°C)
I
DD
vs. Temperature
1200
1000
800
I
DD
(nA)
600
400
200
0
V
DD
= 0V
V
IN
= 4.2V
V
DD
= 3V
V
IN
= 4.2V
I
IN
vs. Temperature
800
600
400
200
0
V
DD
= 3V
V
IN
= 4.2V
80
V
DD
= 0V
V
IN
= 4.2V
-200
-40 -20 0
20 40 60
TEMPERATURE (°C)
80
-200
-40 -20 0
20 40 60
TEMPERATURE (°C)
July 2005
4
M9999-070505
(408) 955-1690
Micrel, Inc.
MIC845
Block Diagrams
V
DD
V
IN
5
V
DD
V
IN
5
V
DD
V
DD
V
TH
INP
3
High-Voltage
Detect
V
TH
OUT
4
INP
3
High-Voltage
Detect
OUT
4
2.55V
Bandgap
Reference
2.55V
Bandgap
Reference
2
GND
MIC845H
2
GND
MIC845L
V
DD
V
IN
5
V
DD
V
TH
INP
3
High-Voltage
Detect
OUT
4
2.55V
Bandgap
Reference
2
GND
MIC845N
V
OUT
V
OUT
V
IN
V
REF
+ Hysteresis
V
REF
V
IN
V
REF
+ Hysteresis
V
REF
Type H and N
Type L
July 2005
5
M9999-070505
(408) 955-1690
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