MIC2785 - Micrel

MIC2785
Dual Supply Voltage Monitor
with Manual Reset
General Description
Features
The MIC2785 is a micropower voltage monitor that
provides undervoltage monitoring and manual reset
capability in a tiny 1.2mm × 1.2mm QFN package. The
MIC2785 provides a monitored voltage input (VIN) separate
from the supply input (VDD). This insures that the reset
(/RST) output maintains a valid output state when the
voltage being monitored ramps up or down. The device
also includes a manual reset input (/MR). The /RST output
is an active low push-pull output.
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The undervoltage detector compares the VIN pin voltage
against the factory-programmed threshold of 1.62V. The
reset output is asserted any time the input voltage drops
below the programmed threshold voltage. A reset can be
generated at any time by asserting the manual reset input,
/MR. This reset output will remain active until the release
of /MR. The /MR input can also be used to daisy-chain the
MIC2785 onto existing power monitoring circuitry or other
supervisors. Hysteresis is included to prevent chattering
due to noise.
The MIC2785 consumes a minimum of quiescent current,
only 5µA, 1.5µA from the main supply pin and 3.5µA from
the input pin. Offered in a tiny space saving 6-pin QFN
1.2mm × 1.2mm package.
No external components
Monitors input voltage for under-voltage condition
Separate inputs for supply (VDD) and monitor (VIN)
+1.5% VIN threshold voltage accuracy
Valid /RST state with VIN down to 0.0V
Valid /RST state with VDD down to 1.20V
Factory-programmed 1.62V reference
Manual reset input (/MR)
Active low RESET (/RST) output
Ultra-low input current – 5µA total (VIN and VDD)
Rejects brief input transients
–40°C to 85°C operating temperature range
RoHS lead-free compliant
Available in 6-pin 1.2mm × 1.2mm Thin QFN package
Applications
• Mobile phones
• PDAs
• GPS Receivers
Datasheets and support documentation are available on
Micrel’s web site at: www.micrel.com.
Typical Application
Memory or Microprocessor Voltage Monitor
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
May 15, 2015
Revision 2.0
Micrel, Inc.
MIC2785
Ordering Information
Part Number(1)
Marking
Typical Application
Voltage
Junction Temperature
Range
Package
MIC2785-16YFT
U1C
1.8V+10%
–40°C to +85°C
6–Pin 1.2mm × 1.2mm Thin QFN Pb-Free
Note:
1. Other voltages are available. Contact Micrel for details.
Pin Configuration
6-Pin (1.2mm × 1.2mm) Thin QFN (FT)
Pin Description
Pin Number
Pin Name
1
NC
Pin Function
Not Internally Connected.
2
VDD
Analog (Input). Independent supply input for internal circuitry.
3
GND
Ground.
4
VIN
Analog (Input). Monitored input voltage. An under-voltage condition will trigger a reset sequence.
/MR
Digital (Input): Asserting this pin low initiates an immediate and unconditional reset. Assuming VIN
is above the threshold when /MR is released (returns high), the reset output will be de-asserted.
/MR may be driven by a logic signal or a mechanical switch. /MR has an internal pull-up to VDD
and may be left floating if unused.
/RST
Digital (Output): Asserted low whenever the VIN pin voltage falls below the reference voltage or
Manual Reset pin (/MR) is asserted. It will remain asserted until VIN voltage rises above the
threshold voltage and the /MR pin is released. The maximum output voltage of the /RST pin is
VIN. /RST is a push-pull output.
5
6
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Micrel, Inc.
MIC2785
Absolute Maximum Ratings(2)
Operating Ratings(3)
Supply Voltage (VDD) ........................................ -0.3V to +6V
Monitor Input (VIN) ............................................ -0.3V to +6V
Input Voltage (V/MR) .......................................... -0.3V to +6V
/RST Current ............................................................. ±20mA
Lead Temperature (soldering, 20sec.) ....................... 260°C
Junction Temperature (TJ) ......................... -40°C to +125°C
Storage Temperature (TS) .......................... -65°C to +150°C
ESD Rating(4) (Human Body Model) ......................... ±1.5kV
Supply Voltage (VDD) .................................... +1.5V to +5.5V
Monitor Input (VIN) ......................................... –0.3V to + VDD
Input Voltage (V/MR) ..................................... –0.3V to + 5.5V
Ambient Temperature (TA) .......................... –40°C to +85°C
Junction Thermal Resistance
6–pin 1.2mm × 1.2mm Thin QFN (θJA) ......... 140.7°C/W
Electrical Characteristics(5)
VDD = 3.1V; VIN = VDD = 3.1V; TA = 25°C, bold values indicate –40°C< TA < +85°C, unless noted.
Symbol
Parameter
Condition
Min.
IDD
Supply Current (VDD)
VIN = VTH +1.6%, /MR & /RST open
1.0
µA
IIN
Supply Current (VIN)
VIN = VTH +1.6%, /MR & /RST open
3.5
µA
VTH Accuracy
Typ.
-1.5
Max.
+1.5
1.5
Units
%
VHYST
Hysteresis Voltage
tPROP_TH
Propagation Delay
VIN = VTH ±1 .5%, ±100mV
VOL
Output Voltage Low
VIN ≤ VTH -1.5%, ISINK = 100µA, VDD > 1.2V
VOH
Output Voltage High
VIN > VTH +1.5%, ISOURCE = 500µA
VIH
Input High Voltage
VDD = 3.1V
VIL
Input Low Voltage
VDD = 3.1V
tPROP_MR
Propagation Delay
V/MR < (VIL –100mV)
0.5
tMIN
Minimum Input Pulse Width
V/MR < VIL reset occurs
33
ns
IPU
Internal Pull-up Current
100
nA
5
%
25
µs
0.3
V
0.8 * VIN
V
1.7
V
/MR Input
0.4
V
25
µs
Notes:
2. Exceeding the absolute maximum ratings may damage the device.
3. The device is not guaranteed to function outside its operating ratings.
4. Devices are ESD sensitive. Handling precautions are recommended. Human body model, 1.5kΩ in series with 100pF.
5. Specification for packaged product only.
May 15, 2015
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Revision 2.0
Micrel, Inc.
MIC2785
Timing Diagram
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MIC2785
Functional Diagram
VREF. The VIN pin circuitry includes hysteresis to
prevent /RST pin chattering due to noise. The VIN pin is
relatively immune to very brief negative-going transients.
Application Information
Design and Product Advantages
The MIC2785’s tiny 1.2mm × 1.2mm Thin QFN package
combined with no external components offers several
advantages
compared
to
conventional
voltage
supervisors.
Reset Output (/RST)
The /RST pin is a complementary push-pull output, which
source and sink current. The reset output is asserted any
time the VIN pin voltage is less than the threshold voltage
(VIN < VTH) or the /MR pin is asserted. The /RST pin
responds very quickly to reset conditions, typically
asserting within 5µs of VIN < VTH.
Tremendous savings are captured with decreased board
size, reduced circuit complexity, and decreased bill of
material (BOM) cost.
Power Supply Input (VDD)
The VDD pin provides a stable input power for the
internal circuitry. This insures that the reference circuitry
and monitoring circuitry have a stable voltage over the
entire operating voltage range.
The MIC2785 securely monitors the supply voltage of
critical
components
like
microcontrollers
and
microprocessors. With the MIC2785’s /RST pin
connected to the μP’s reset pin, the processor will be
properly reset at power on and during power-down and
brown-out conditions.
Supply bypassing is not required. However, bypassing
may be valuable depending on the quality of the system
voltage to which the VDD pin is connected. If bypassing
is added, connect the capacitor(s) as closely as possible
to the VDD pin. Place the lowest value capacitors closest
to the VDD pin.
Manual Reset Input (/MR)
The /MR pin provides the ability to initiate a reset via
external logic or a manual switch. This is in addition to
the MIC2785’s automatic voltage monitoring function.
Asserting the /MR input to a logic low causes an
immediate and unconditional reset. Assuming the VIN pin
voltage is within tolerance when /MR is released (returns
high), the reset output will be de-asserted. /MR is
internally pulled-up to VDD and may be left floating/ open
if unused.
Under-Voltage Detector Input (VIN)
The largest portion of the monitoring circuitry is the VIN
comparator. The VIN pin is connected to the noninverting terminal of the comparator. The internal
reference is connected to the inverting terminal of the
comparator. A reset is triggered when VIN falls below
May 15, 2015
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Revision 2.0
Micrel, Inc.
MIC2785
Package Information and Recommended Landing Pattern(6)
6-Pin (1.2mm × 1.2mm) Thin QFN (FT)
Note:
6. Package information is correct as of the publication date. For updates and most current information, go to www.micrel.com.
May 15, 2015
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Revision 2.0
Micrel, Inc.
MIC2785
Package Information and Recommended Landing Pattern(6) (Continued)
May 15, 2015
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Micrel, Inc.
MIC2785
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com
Micrel, Inc. is a leading global manufacturer of IC solutions for the worldwide high performance linear and power, LAN, and timing & communications
markets. The Company’s products include advanced mixed-signal, analog & power semiconductors; high-performance communication, clock
management, MEMs-based clock oscillators & crystal-less clock generators, Ethernet switches, and physical layer transceiver ICs. Company
customers include leading manufacturers of enterprise, consumer, industrial, mobile, telecommunications, automotive, and computer products.
Corporation headquarters and state-of-the-art wafer fabrication facilities are located in San Jose, CA, with regional sales and support offices and
advanced technology design centers situated throughout the Americas, Europe, and Asia. Additionally, the Company maintains an extensive network
of distributors and reps worldwide.
Micrel makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this datasheet. This
information is not intended as a warranty and Micrel does not assume responsibility for its use. Micrel reserves the right to change circuitry,
specifications and descriptions at any time without notice. No license, whether express, implied, arising by estoppel or otherwise, to any intellectual
property rights is granted by this document. Except as provided in Micrel’s terms and conditions of sale for such products, Micrel assumes no liability
whatsoever, and Micrel disclaims any express or implied warranty relating to the sale and/or use of Micrel products including liability or warranties
relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright, or other intellectual property right.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product
can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical
implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A
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© 2009 Micrel, Incorporated.
May 15, 2015
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