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MIC2772
Dual Voltage Supervisor
General Description
The MIC2772 is a dual power supply supervisor that provides under-voltage monitoring and power-on reset generation. It may replace two discrete voltage supervisors such as MIC1810, MIC1815, MIC809, MIC811, MIC6315, etc. The two voltage supervisors are completely independent. Each functional block features an under-voltage detector, a delay-generator, and a de-bounced manual reset input. A wide choice of voltage thresholds is available. The reset output is asserted at power-on and any time the input voltage drops below the reference voltage. It remains asserted for the chosen timeout period after the input rises back above the threshold. Reset timeouts of 20, 140, and 1100ms (minimum) are available. A reset can be generated at any time by asserting the manual reset input, /MR. This input is internally de-bounced, and the reset output will remain active for the timeout period after the release of /MR. The /MR input can also be used to daisy-chain one or more of the MIC2772's supervisors onto existing power monitoring circuitry or other supervisors. The tiny 2x2mm MLF package has a footprint smaller than that of a single SOT23 voltage supervisor. Data sheets and support documentation can be found on Micrel's web site at www.micrel.com.
Features
* * * * * * * * * Two independent voltage supervisors Directly replaces discrete supervisors Generates power-on reset pulses De-bounced manual reset Inputs Choice of voltage thresholds 20, 140, or 1100ms reset timeouts Reset output may be pulled above VCC Rejects brief input transients Ultra-small 2x2mm MLF package
Applications
* * * * * * Servers Embedded Controllers Telecommunications Systems Power Supply Sequencing Hot-swapping Power supplies
____________________________________________________________________________________________________
Typical Application
VCC1 10k MR1 VCC1 RESET1 GND1 VCC2 10k MR2 VCC2 RESET2 GND2 VCC RESET GND P VCC RESET GND P
MIC2772 Typical Application Circuit
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MIC2772
Ordering Information
Part Number Standard Pb-Free MIC2772-L2L3YML(2) MIC2772-M2M3YML (2) MIC2772-L3L3YML(1) MIC2772-M3M3YML(1) MIC2772-T3T3YML(1) MIC2772-S3S3YML(1) MIC2772-T2T3YML(2) MIC2772-S2S3YML(2) MIC2772-L3T3YML(2) MIC2772-M3S3YML(2) Top Mark Standard Pb-Free UP0 UP1 UP2 UP3 UP4 UP5 UP6 UP7 UP8 UP9 Supervisor 1 tRESET VTH (V) (ms) 4.63 20 4.38 20 4.63 140 4.38 140 3.08 140 2.93 140 3.08 20 2.93 20 4.63 140 4.38 140 Supervisor 2 tRESET VTH (V) (ms) 4.63 140 4.38 140 4.63 140 4.38 140 3.08 140 2.93 140 3.08 140 2.93 140 3.08 140 2.93 140
MIC2772-L3L3BML(1) MIC2772-M3M3BML(1) MIC2772-T3T3BML(1) MIC2772-S3S3BML(1)
UP2 UP3 UP4 UP5
Note: 1. 2. Available now. Contact factory.
Pin Configuration
MR1 GND1 MR2 GND2 1 2 3 4 8 7 6 5 VCC1 RESET1 VCC2 RESET2
8-lead 2mm X 2mm MLF(ML)
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Pin Description
Pin Number Pin Name Pin Function
Digital Input; supervisor 1. Driving this pin low initiates an immediate and unconditional reset. If VCC1 is above the threshold when /MR1 is released (returns high), RESET1 will be de-asserted no less than tRESET1 later. /MR1 may be driven by a CMOS or TTL logic signal or a mechanical switch. De-bouncing is performed internally. /MR1 has an internal pull-up to VCC1; leave open if unused. Ground return for supervisor 1. Digital Input; supervisor 2. Driving this pin low initiates an immediate and unconditional reset. If VCC2 is above the threshold when /MR2 is released (returns high), the /RESET2 will be de-asserted no less than tRESET2 later. /MR2 may be driven by a CMOS or TTL logic signal or a mechanical switch. Debouncing is performed internally. /MR2 has an internal pull-up to VCC2; leave open if unused. Ground return for supervisor 2. Digital Output; open-drain; supervisor 2. Asserted low whenever VCC2 falls below the threshold voltage. It remains asserted for no less than tRESET2 and is de-asserted after VCC2 returns above the threshold. Analog Input. Power supply input for supervisor 2. Digital Output; open-drain; supervisor 1. Asserted low whenever VCC1 falls below the threshold voltage. It remains asserted for no less than tRESET1 and is de-asserted after VCC1 returns above the threshold. Analog Input. Power supply input for supervisor 1.
1
/MR1
2
GND1
3
/MR2
4 5 6 7 8
GND2 /RESET2 VCC2 /RESET1 VCC1
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Absolute Maximum Ratings(1)
Supply Voltage, VCC ...............................-0.3V to 6.0V Input Voltage, /MR ....................... -0.3V to VCC + 0.3V Input Voltage, /RESET ..........................-0.3V to 6.0V Input Current (VCC, /MR) ................................. 20mA Output Current (/RESET) ................................ 20mA Storage Temperature....................... -65C to +150C ESD Rating (Note 3) .............................................3kV
Operating Ratings(2)
Supply Voltage...........................................1V to 5.5V Input Voltage (/MR )..................................... 0 to 5.5V Input Voltage (/RESET ) ............................ 0 to +5.5V Operating Temperature Range (TA).... -40C to +85C Lead Temperature - Soldering, 10s .................300C Package Thermal Resistance (JA)................ 93C/W
Electrical Characteristics
For typical values, TA = 25C, 2.5V VCCn 5.5V; values in bold are for 2.5V VCCn 5.5V, TMIN TA TMAX, unless otherwise noted.
Symbol
IDD
Parameter
Supply Current
Condition
/MR1 = /MR2 = /RESET1 = /RESET2 = open, VCC1 = VCC2 = 5.5V /MR1 = /MR2 = /RESET1 = /RESET2 = open, VCC1 = VCC2 = 3.6V /MR1 = /MR2 = /RESET1 = /RESET2 = open, VCCn = 0V, VCCm = 5.5V /MR1 = /MR2 = /RESET1 = /RESET2 = open, VCCn = 0V, VCCm = 3.6V
Min
Typ
10 10 5 5
Max 30 20 15 10
Units
A A A A
Power Supply
/RESETn OUTPUTS VTHn Reset-voltage threshold L voltage code M voltage code S voltage code T voltage code tRESET Reset Pulse Width timeout code = 2 timeout code = 3 timeout code = 4 VOL /RESET Output Voltage Low VCCn 4.25V, ISINK = 3.2mA VCCn 2.5V, ISINK = 1.2mA VCCn 1V, ISINK = 50A ILEAK VIH Output leakage Input Voltage, High /RESET not asserted VTHn > 4.0V VTHn < 4.0V VIL Input Voltage, Low VTHn > 4.0V VTHn < 4.0V /MRn INPUTS
4.5 4.25 2.85 3.00 20 140 1100
4.63 4.38 2.93 3.08
4.75 4.50 3.00 3.15 44
V V V V ms
320 2500 0.4 0.3 0.3 1
V V V
A
V V
2.3 0.7*V CC 0.8 0.25* VCC
V V
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Electrical Characteristics cont.
Symbol
tPROP tMIN tREJECT RPU
Parameter
/MR to /RESET Propagation Delay Minimum Input Pulse Width Widest Pulse Ignored Pull-up Resistance
Condition
/MRn < VIL /RESETn < VIL Reset Occurs No Reset Occurs
Min
Typ
0.5
Max
Units
s s
10
100
ns
10
20
30
k
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.
Timing Diagram
VCCn VTH
/MRn
/RESETn
tRST
tRST
MIC2772 Timing Diagram
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Functional Block Diagram
VCC
MR1 (1)
RESET GENERATOR
RESET1 (7)
VCC1 (8) Reset Threshold (V) GND1 (2)
+
VCC
MR2 (3)
RESET GENERATOR
RESET2 (5)
VCC2 (6) Reset Threshold (V) GND2 (4)
+
MIC2772 Block Diagram
Application Information
Reset Output, /RESET The /RESET pin is active low (open drain) pin. The /RESET pin is asserted whenever VCC falls below the reset threshold voltage or if /MR (manual reset) is forced low. The /RESET pin remains asserted for the duration of the threshold timeout period after VCC has risen above the reset threshold and/or /MR has returned high. The reset function ensures the microprocessor is properly reset and power up in a known condition after a power failure. /RESET will remain valid with VCC as low as 1.0V. The /RESET output is a simple open-drain Nchannel MOSFET structure. A pull-up resistor must be used to pull this output to some voltage. For most applications, this voltage will be the same power supply that supplies VCC to MIC2772. It is possible however to tie this resistor to some other voltage. This will allow the MIC2772 to monitor one voltage while level-shifting the /RESET output to some other voltage. The pull-up voltage must be limited to 6.0V or less (absolute maximum) to avoid damage to the MIC2772. The resistor must be small enough to supply current to the inputs and leakage paths that are driven by the /RESET output. April 2005 6 Manual Reset Input, /MR The ability to initiate a reset via external logic or a manual switch is provided in addition to the MIC2772's automatic supervisory functions. Driving the /MR input to a logic low causes an immediate and unconditional reset to occur. Assuming VCC is within tolerance when /MR is released (returns high), the /RESET output will be de-asserted no less than tRESET later. /MR may be driven by a CMOS or TTL logic signal, or a mechanical switch. Typically, a momentary push-button switch is connected such that /MR is shorted to ground when the switch contacts close. Switch de-bouncing is performed internally; the switch may be connected directly between /MR and GND. /MR has an internal 20k pull-up resistor (typical) to VCC and may be left open if unused.
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MIC2772
Transients on VCC The MIC2772 is inherently immune to very short "glitches" on VCC. In the case of very brief transients, VCC may drop below the reset-voltage threshold without triggering a reset. As shown in the graph, the MIC2772 is relatively immune to transients with typical duration of 25us. The lines on the graph represent the typical allowable transient duration for a given amount of threshold overdrive that will not generate a reset. The data was taken by adding negative-going square-wave pulse to a DC input voltage set at 0.5V above actual measured threshold for the part being characterized. Figure 1 shows the graph for the MIC2772[UP3] and Figure 2 shows the graph for the MIC2772[UP5]
35 30 25 20 15 10 5 0 VTH = 4.393V
Motorola 68HC11 family is one example. Because the MIC2772's output is active-low, open-drain, it can be connected directly to the processor's reset pin with only the pull-up resistor normally required.
MIC2772 Replaces Single Supervisor
The table below lists common single voltage supervisors that can be considered for replacement by MIC2772.
P/N Suffix L2L3
Supervisor #1 MIC6315-46D2
Supervisor #2 MIC1810-5, MIC6315-46D3, MIC809L, MIC811L MIC1810-10, MIC6315-44D3, MIC809M, MIC811M MIC1810-5, MIC6315-46D3, MIC809L, MIC811L MIC1810-10, MIC6315-44D3, MIC809M, MIC811M MIC6315-31D3, MIC809T, MIC811T MIC1815-10, MIC6315-29D3, MIC809S, MIC811S MIC6315-31D3, MIC809T, MIC811T MIC1815-10, MIC6315-29D3, MIC809S, MIC811S MIC6315-31D3, MIC809T, MIC811T MIC1815-10, MIC6315-29D3, MIC809S, MIC811S
Typical Transient Response
M2M3
MIC6315-44D2
MAX. TRANSIENT DURATION (s)
L3L3
MIC1810-5, MIC6315-46D3, MIC809L, MIC811L MIC1810-10, MIC6315-44D3, MIC809M, MIC811M MIC6315-31D3, MIC809T, MIC811T MIC1815-10, MIC6315-29D3, MIC809S, MIC811S MIC6315-31D2 MIC6315-29D2
M3M3
0 200 400 600 800 1000 RESET COMP. OVERDRIVE VTH - VCC (mV)
T3T3 S3S3
Figure 1
40 35 30 25 20 15 10 5 VTH = 2.933V
Typical Transient Response
MAX. TRANSIENT DURATION (s)
T2T3 S2S3
L3T3
0 0 200 400 600 800 1000 RESET COMP. OVERDRIVE VTH - VCC (mV)
MIC1810-5, MIC6315-46D3, MIC809L, MIC811L MIC1810-10, MIC6315-44D3, MIC809M, MIC811M
M3S3
Figure 2
Interfacing to Processors with Bi-directional Reset Pins Some microprocessors have reset signal pins that are bi-directional, rather than input only. The
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Package Information
8-Pin 2mm X 2mm MLF (ML)
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
The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer. 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 Purchaser's use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser's own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. (c) 2005 Micrel, Incorporated.
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