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MIC2779H-1YM5-TR

P1-P3P4-P6
January 2006 1 MIC2779
MIC2779 Micrel, Inc.
MIC2779
Voltage Monitor with Adjustable Hysteresis
General Description
The MIC2779 is a voltage monitor—uniquely designed to
detect two separate voltage thresholds—combined with a
delay generator and logic. It is designed for monitoring the
battery supply of portable digital systems, particularly PDAs,
pagers, and cellular telephones.
High- and low-voltage thresholds can be adjusted inde-
pendently, allowing for wide hysteresis. Voltage detection
thresholds are accurate to 2%.
If the battery voltage falls below the low-voltage threshold,
the output /RST or RST is asserted and latched, preventing
system operation until the battery is replaced or recharged.
Internal logic prevents the output from chattering due to battery
recovery or load removal. The output is asserted for 140ms
(minimum) when a fresh battery is inserted. For applications
requiring open-drain output, see MIC2778/MIC833.
The IC’s power supply input is separate from the detector
inputs, allowing the MIC2779 to be powered from a down-
stream supply, such a boost converter. Supply current is
extremely low (1µA, typical), making it ideal for portable
applications.
A high-precision 1% grade is available. The MIC2779 is sup-
plied in Micrel’s IttyBitty™ 5-pin SOT-23-5 package.
Typical Application
HTH
/ RST
VDD
LTH
GND
MIC2779L
604k
1%
56k
1%
340k
1%
EN
OUT
IN
B Y P
GND
MIC5207-3.0BM5
Li-Ion
Cell
470pF
V
OU T
3.0V
4.7µF
V
BAT(hi)
= 3.6V
V
BAT(lo)
= 3.1V
Cellular Telephone Battery Monitor
Features
• Optimized for PDAs, cellular telephones, pagers,
and other battery-powered devices
• Independently adjustable high- and
low-voltage thresholds
• Internal logic prevents battery-voltage-fluctuation chatter
• High ±2% voltage threshold accuracy; 1% available
• Built in 140ms (minimum) delay deglitches output
• Extremely low 1µA typical supply current
• For applications requiring open-drain output, see
MIC2778/MIC833
• Immune to brief power supply transients
• 5-pin SOT-23 package
Applications
• PDAs
• Pagers
• Cordless phones
• Consumer electronics
• Embedded controllers
• Personal electronics
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.
MIC2779 Micrel, Inc.
MIC2779 2 January 2006
Pin Configuration
HTH
VDDRST
LTH
13
4 5
2
GND
SOT-23-5 (M5)
“H” Version
Ordering Information
Part Number
Output Polarity Accuracy Temperature Range Package
Standard Marking Pb-Free Marking
MIC2779H-2BM5 UPA2 MIC2779H-2YM5 UPA2 Active-High RST 2% –40ºC to +85ºC SOT-23-5
MIC2779H-1BM5 UPA1 MIC2779H-1YM5 UPA1 Active-High RST 1% –40ºC to +85ºC SOT-23-5
MIC2779L-2BM5 UPB2 MIC2779L-2YM5 UPB2 Active-Low /RST 2% –40ºC to +85ºC SOT-23-5
MIC2779L-1BM5 UPB1 MIC2779L-1YM5 UPB1 Active-Low /RST 1% –40ºC to +85ºC SOT-23-5
HTH
VDD/RST
LTH
13
4 5
2
GND
SOT-23-5 (M5)
“L” Version
Pin Description
Pin Number Pin Number Pin Name Pin Function
MIC2779H MIC2779L
1 1 HTH
High-Voltage Theshold (Input): Analog input to a comparator. When the
level on this pin initially rises above V
REF
, the delay generator cycles and the
/RST remains low or RST remains high for a minimum of 140ms.
2 2 GND Ground
3 3 LTH Low-Voltage Threshold (Input): Analog input to a comparator. This is the
voltage monitor input assigned to detect a low voltage condition. When the
level on this pin falls below V
REF
, /RST or RST is asserted and the condition
is latched until V
HTH
> V
REF
.
4 RST Reset (Output): Push-pull output. This output is asserted and latched when
V
LTH
<V
REF
, indicating a low voltage condition. This state remains latched
until V
HTH
> V
REF
. The polarity of this signal (active-high or low) is deter
mined by the part number suffix. See ordering information.
4 /RST Reset (Output): Push-pull output. This output is asserted and latched when
V
LTH
<V
REF
, indicating a low voltage condition. This state remains latched
until V
HTH
> V
REF
. The polarity of this signal (active-high or low) is deter
mined by the part number suffix. See ordering information.
5 5 VDD Power Supply (Input): Independent supply input for internal circuitry.
January 2006 3 MIC2779
MIC2779 Micrel, Inc.
Absolute Maximum Ratings (Note 1)
Supply Voltage (V
DD
) .......................................–0.3V to +7V
Input Voltages (V
LTH
, V
HTH
, V
/RST
, V
RST
) ........–0.3V to +7V
/RST, RST Output Current (I
/RST
), (I
RST
) .................... 20mA
Storage Temperature (T
S
) ........................ –65°C to +150°C
ESD Rating, Note 3 ....................................................... 2kV
Operating Ratings (Note 2)
Supply Voltage (V
DD
) .................................. +1.5V to +5.5V
Input Voltages (V
LTH
, V
HTH
, V
/RST
, V
RST
) .....–0.3V to +6.0V
Ambient Temperature Range (T
A
) .............. –40°C to +85°C
Package Thermal Resistance ................................
256°C/W
Electrical Characteristics
1.5V ≤ V
DD
≤ 5.5V; T
A
= +25°C, bold values indicate –40°C ≤ T
A
≤ +85°C; unless noted
Symbol Parameter Condition Min Typ Max Units
I
DD
Supply Current /RST, RST not asserted 1 2
µA
I
LTH,
I
HTH
Input Leakage Current 5 pA
10
nA
V
REF
Reference Voltage 1.240 V
MIC2779H/L-2
1.215 1.265 V
MIC2779H/L-1
1.228 1.252 V
t
D
Propagation Delay V
LTH
= V
REF(max)
+100mV to 5 µs
V
REF(min)
– 100mV
t
RESET
Reset Pulse Width 140 420 ms
V
OL
Reset Output Low Voltage /RST asserted or RST not asserted,
I
SINK
= 1.6mA, V
DD
≥ 1.6V 0.3 V
/RST asserted or RST not asserted,
I
SINK
= 100µA, V
DD
≥ 1.2V, 0.4 V
V
OH
Reset Output High Voltage /RST not asserted or RST asserted,
I
SOURCE
= 500µA, V
DD
≥ 1.6V 0.8V
DD
V
/RST not asserted or RST asserted,
I
SOURCE
= 50µA, V
DD
≥ 1.2V, 0.8V
DD
V
Note 1. Exceeding the absolute maximum rating may damage the device.
Note 2. The device is not guaranteed to function outside its operating rating.
Note 3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
Note 4. V
DD
operating range is 1.5V to 5.5V. Output is guaranteed to be held low down to V
DD
= 1.2V.
Timing Diagram
V
HTH
V
BATT
V
LTH
0V
V
OH
V
OL
t
RST
t
RST
A
A
V
/RST
V
OH
V
OL
V
RST
Propagation delays not shown for clarity.
Note A. The MIC2779 ignores very brief transients.
See “Applications Information” for details.
P1-P3P4-P6

MIC2779H-1YM5-TR

Mfr. #:
Buy MIC2779H-1YM5-TR
Manufacturer:
Microchip Technology / Micrel
Description:
Supervisory Circuits V-Supervisor w/Adj. Hysteresis, Open-Drain Ouput, 1% Accuracy
Lifecycle:
New from this manufacturer.
Delivery:
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