MIC2774H-23YM5-TR [MICROCHIP]

2-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO5;


型号：	MIC2774H-23YM5-TR
厂家：	MICROCHIP
描述：	2-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO5 输入元件光电二极管
文件：	总11页 (文件大小：435K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

MIC2774

Dual Micro-Power Low Voltage Supervisor

General Description

Features

The MIC2774 is a dual power supply supervisor that

provides undervoltage monitoring, manual reset capability,

and power-on reset generation in a compact 5-pin SOT-23

package. Features include two undervoltage detectors,

one fixed and one adjustable, and a choice of reset

outputs. One undervoltage detector compares V_DDagainst

a fixed threshold. Ten factory-programmed thresholds are

available. The second, user-adjustable input is compared

against a 300mV reference. This low reference voltage

allows for the monitoring of voltages lower than those

supported by previous supervisor ICs.

• Monitors two independent power supplies for

undervoltage conditions

• One fixed and one user-adjustable input

• Choice of ten factory-programmed thresholds

• Adjustable input can monitor supplies as low as 0.3V

• Generates 140ms (min.) power-on reset pulse

• Manual reset input

• Choice of active-high, active-low, or open-drain active-

low reset outputs

• Inputs may be pulled above V_DD(7V abs. max.)

• /RST output valid down to 1.2V

• Ultra-low supply current, 3.5µA typical

• Rejects brief input transients

• IttyBitty™ 5-pin SOT-23 package

• Pin-compatible upgrade for MAX6306/09/12

The reset outputs are asserted at power-on and at any

time either voltage drops below the programmed threshold

voltage and remains asserted for 140ms (min.) after they

subsequently rise back above the threshold boundaries.

Manual reset functionality can be provided by a switch

connected between ground and the /MR input. A wide

choice of voltage thresholds provides for a variety of

supply voltages and tolerances. Hysteresis is included to

prevent chattering due to noise. Typical supply current is a

low 3.5µA.

Applications

• Monitoring processor ASIC or FPGA core and I/O

voltages

Datasheets and support documentation are available on

Micrel’s website at: www.micrel.com.

• PDAs, hand-held PCs

• Embedded controllers

• Telecommunications systems

• Power supplies

• Wireless/cellular systems

• Networking hardware

Typical Application

IttyBitty 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

March 16, 2015 Revision 2.0

Micrel, Inc.

MIC2774

Ordering Information

Part Number^(1,2)

Marking^(1,3)

Reset Output

Junction Temperature Range

–40°C to +85°C

Package⁽⁴⁾

MIC2774N-XXYM5

MIC2774H-XXYM5

MIC2774L-XXYM5

UGXX

UHXX

UIXX

Open-Drain. Active-Low (/RST)

Active-High. Complementary (RST)

Active-Low. Complementary (/RST)

SOT-23-5

–40°C to +85°C

Note:

1. XX = voltage code, see table below.

2. Order entry part number, add “ TR”. Example: MIC2774N-22YM5 TR.

3. Underbar symbol (__) may not be to scale.

4. Standard reel SOT-23: Reel diameter is 7 inches, hub diameter is 2 inches, width is 8mm.

Standard Voltage Options⁽⁵⁾

Voltage Code

Typical Application (V_DD

)

Nominal Threshold Voltage (V_TH)

5.0V ±5%

4.68V

4.43V

3.09V

2.93V

2.81V

2.67V

2.53V

2.34V

2.25V

1.69V

5.0V ±10%

3.3V ±5%

3.3V ±10%

3.0V ±5%

2.85V ±5%

2.7V ±5%

2.5V ±5%

2.4V ±5%

1.8V ±5%

Note:

5. There are ten standard versions available with an order increment of 3,000 pieces. Samples of standard versions are normally available from stock.

Contact factory for information on non-standard versions. Available in tape-and-reel only.

Part Number Convention

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MIC2774

Pin Configuration

SOT-23-5 (M5)

“H” Version

SOT-23-5 (M5)

“L” and “N” Version

Pin Description

Pin Number

MIC2774L

MIC2774N

Pin Number

MIC2774H

Pin Name

Pin Function

Digital (Output): Asserted high whenever V_INor V_DDfalls below the threshold

voltage. It will remain asserted for no less than 140ms after V_INand V_DDreturn

above the threshold limits.

RST

Digital (Output): Asserted low whenever V_INor V_DDfalls below the threshold

voltage. It will remain asserted for no less than 140ms after V_INand V_DDreturn

above the threshold limits. (Open-drain for “N” version, requires an external

pull-up resistor).

/RST

GND

Ground

Digital (Input): Driving this pin low initiates immediate and unconditional reset.

Assuming V_INand V_DDare above the thresholds when /MR is released

(returns high), the reset output will be de-asserted no less than 140ms later.

/MR may be driven by a logic signal or a mechanical switch. /MR has an

internal pull-up to V_DDand may be left open if unused.

/MR

Analog (Input): The voltage on this pin is compared to the internal 300mV

reference. An undervoltage condition will trigger a reset sequence.

Analog (Input): Power supply input for internal circuitry and input to the fixed

voltage monitor. The voltage on this pin is compared against the internal

reference. An undervoltage condition will trigger a reset sequence.

VDD

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Micrel, Inc.

MIC2774

Absolute Maximum Ratings⁽⁶⁾

Operating Ratings⁽⁷⁾

Supply Voltage (V_DD).................................... –0.3V to +7.0V

Input Voltages (V_IN, V_/MR) ............................. –0.3V to +7.0V

Output Voltages (V_/RST, V_RST) ....................... –0.3V to +7.0V

RST, (/RST) Current ...................................................20mA

Storage Temperature (Ts).........................–65°C to +150°C

ESD Rating⁽⁸⁾...............................................................1.5kV

Supply Voltage (V_DD).................................... +1.5V to +5.5V

Input Voltages (V_IN, V_/MR) ............................. –0.3V to +6.0V

Output Voltages

V_/RST(N version) .................................... –0.3V to +6.0V

V_/RST, V_RST(H and L versions) .... –0.3V to V_DDto +0.3V

Ambient Temperature (T_A)..........................–40°C to +85°C

Package Thermal Resistance (θ_JA)........................256°C/W

Electrical Characteristics⁽⁹⁾

Note 10; T_A= +25°C, bold values indicate –40°C≤ T_A≤ +85°C, unless noted.

Symbol

Parameter

Condition

Min.

Typ.

Max.

Units

V_DD= V_IN= V_TH+ 1.6%;

Note 10; /MR, RST, /RST open

I_DD

Supply Current

3.5

µA

VDD Voltage Threshold

Undervoltage Threshold on V_DD

V_TH

1.5%

V_TH+

1.5%

(See Standard Voltage Options

table)

V_TH

V_HYST

Hysteresis Voltage

IN, Undervoltage Detector Input

295

305

V_REF

Undervoltage Threshold

Hysteresis Voltage

Note 10

300

V_HYST

I_IN

Input Current

T_MIN≤ T_A≤ T_MAX

RST, /RST Outputs

t_PROPPropagation Delay

t_RST

V_IN= (V_REF(MAX)+ 100mV) to

µs

_IN= (V_REF(MIN)– 100mV), /MR = open

T_MIN≤ T_A≤ T_MAX

_SINK= 1.6mA; V_DD≥ 1.6V

I_SINK= 100µA; V_DD≥ 1.2V; Note 11

140

280

0.3

Reset Pulse Width

RST or /RST Output Voltage

Low

V_OL

0.8 ×

V_DD

_SOURCE= 500µA; V_DD≥ 1.5V

RST or /RST Output Voltage

High (H and L versions)

V_OH

0.8 ×

V_DD

I_SOURCE= 10µA; V_DD≥ 1.2V; Note 11

Notes:

6. Exceeding the absolute maximum ratings may damage the device.

7. The device is not guaranteed to function outside its operating ratings.

8. Devices are ESD sensitive. Handling precautions are recommended. Human body model, 1.5kΩ in series with 100pF.

9. Specification for packaged product only

10. V_DDequals nominal “Typical Application (V_DD)” as shown in the Standard Voltage Options table.

11. V_DDoperating range is 1.5V to 5.5V. Output is guaranteed to be asserted down to V_DD= 1.2V.

March 16, 2015

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Micrel, Inc.

MIC2774

Electrical Characteristics⁽⁹⁾

Note 10; T_A= +25°C, bold values indicate –40°C≤ T_A≤ +85°C, unless noted.

Symbol

Parameter

Condition

Min.

Typ.

Max.

Units

/MR Inputs

0.7 ×

V_DD

V_IH

V_IL

Input High Voltage

Input Low Voltage

Note 10

0.3 ×

V_DD

t_PROP

t_MIN

I_PU

Propagation Delay

V_/MR< (V_IL– 100mV); Note 10

Reset occurs, V_/MR< V_IL

µs

Minimum Input Pulse Width

Internal Pull-Up Current

Input Current, /MR

250

100

I_IN

V_/MR< V_IL

Timing Diagram

Notes:

12. Propagation delays not shown for clarity.

13. The MIC2774 ignores very brief transients. See the Application Information section for details.

March 16, 2015

Revision 2.0

Micrel, Inc.

MIC2774

Functional Diagram

Note: *Pinout and polarity vary by device type. See the Ordering Information table.

RST, /RST Reset Output

Functional Description

Typically, the MIC2774 is used to monitor the power

supplies of intelligent circuits such as microcontrollers

and microprocessors. By connecting the appropriate

reset output of an MIC2774 to the reset input of a µC or

µP, the processor will be properly reset at power-on,

power-down, and during brown-out conditions. In

addition, asserting /MR, the manual reset input, will

activate the reset function.

IN, Undervoltage Detector Input

The voltage present at the IN pin is compared to the

internal 300mV reference voltage. A reset is triggered if

and when V_INfalls below V_REF. Typically, a resistor divider

is used to scale the input voltage to be monitored such

that V_INwill fall below V_REFas the voltage being

monitored falls below the desired trip-point. Hysteresis is

employed to prevent chattering due to noise. The

comparator on the IN pin is relatively immunue to very

brief negative-going transients.

The reset output is asserted any time /MR is asserted of

if V_INor V_DDdrops below the corresponding threshold

voltage. The reset output remains asserted for t_RST(min)

after V_INand/or V_DDsubsequently return above the

threshold boundaries and/or /MR is released. A reset

pulse is also generated at power-on. Hysteresis

isincluded in the comparators to prevent chattering of the

output due to noise.

VDD Input

The VDD pin is both the power supply terminal and a

monitored input voltage. The voltage at this pin is

continually compared against the internal reference. The

trip-point at which a reset occurs is factory-programmed.

A reset is triggered if and when V_DDfalls below the trip-

point. Hysteresis is employed to prevent chattering due to

noise. The comparator on the VDD input is relatively

immune to very brief negative-going transients.

/MR, Manual Reset Input

The ability to initiate a reset via external logic or a manual

switch is provided in addition to the MIC2774’s automatic

supervisory functions. Driving the /MR input to a logic low

causes an immediate and unconditional reset to occur.

Assuming V_INand V_DDare within tolerance when /MR is

released (returns high), the reset output will be de-

asserted no less than t_RSTlater. /MR may be driven by a

logic signal or 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 is

internally pulled-up to V_DDand may be left open if

unused.

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MIC2774

above regarding the maximum total value of R1 + R2 are

followed, this error contribution will be very small thanks

to the MIC2774’s very low input bias current.

Application Information

Programming the Voltage Threshold

Referring to the Typical Application circuit, the voltage

threshold on the IN pin is calculated as follows:

To summarize, the various potential error sources are:

•

Variation in V_REF: specified at ±1.5%

Resistor tolerance: chosen by designer (typically

≤±1%)

(푅1+푅2)

V_IH= V_REF

푅2

•

Input bias current, I_IN: calculated once resistor values

are known, typically very small

where V_REF= 0.300V

Taking the various potential error sources into account,

the threshold voltage will be set slight below the minimum

V_COREspecification of 0.950V so that when the actual

threshold voltage is at its maximum, it will not intrude into

the normal operating range of V_CORE. The target threshold

voltage will be set as follows:

In order to provide the additional criteria needed to solve

for the resistor values, the resistorscan be selected such

that the two resistors have a given total value; that is, R1

+ R2 = R_TOTAL. Imposing this condition on the resistor

values provides two equations that can be solved for the

two unknown resistor values. A value such as 1MΩ for

R_TOTALis a reasonable choice because it keeps quiescent

current to a generally acceptable level while not causing

any measurable errors due to input bias currents. The

larger the resistors, the larger the potential errors due to

input bias current (I_IN). The maximum recommended

value of R_TOTALis 3MΩ.

Given that the total tolerance on V_THfor the IN pin is [V_REF

tolerance] + [resistor tolerance]

= ±1.5% + ±1% = ±2.5%,

and V_TH(max)= V_CORE(min)

then V_CORE(min)= V_TH+ 2.5% V_TH= 1.025 V_TH,

therefore, solving for V_THresults in

Applying this criteria and rearranging the V_IHexpression

to solve for the resistor values gives:

푉

(

)

0.950

1.025

퐶ꢀ푅ꢃ min

V_TH

= 0.9268ꢆ

)(

)

R2 = ⁽

푅

푉

1.025

푇ꢀ푇ꢁꢂ

푉

푅ꢃꢄ

퐼ꢅ

Solving for R1 and R2 using this value for VTH and the

equations above yields:

R1 = R_TOTAL– R2

R1 = 676.3kΩ ≈ 673kΩ

R2 = 323.7kΩ ≈ 324kΩ

Application Example

Figure illustrates

hypothetical MIC2774L-23

The resulting circuit is shown in Figure 1.

Input Bias Current Effects

application in which the MIC2774L-23 is used to monitor

the core and I/O supplies of a high-performance CPU or

DSP. The core supply, V_CORE, in the example is 1.0V

±5%. The main power rail and I/O voltage, V_I/O, is 2.5V

±5%. As shown in Figure 1, the MIC2774 is powered by

V_I/O. The minimum value of V_I/Ois 2.5V - 5% = 2.375V;

the maximum is 2.5V + 5% = 2.625V. This is well within

the device’s supply range of 1.5V to 5.5V.

Now that the resistor values are known, it is possible to

calculate the maximum potential error due to input bias

current, I_IN. As shown in the Electrical Characteristics

table, the maximum value of I_INis 10nA. Note that the

typical value is a much smaller 5pA. The magnitude of

the offset caused by I_INis given by:

Resistors R1 and R2 must be selected to correspond to

the V_COREsupply of 1.0V. The goal is to ensure that the

core supply voltage is adequate to ensure proper

operation; i.e., V_CORE≥ (1.0V – 5%) = 0.950V. Because

there is always a small degree of uncertainty due to the

accuracy of the resistors, variations in the device’s

voltage reference, etc., the threshold will be set slightly

below this value. The potential variation in the MIC2774’s

voltage reference (V_REF) is specified as ±1.5%. The

resistors chosen will have their own tolerance

specifications. This example assumes the use of 1%

accurate resistors. The potential worst-case error

contribution due to input bias current can be calculated

once the resistor values are chosen. If the guidelines

_ERROR= I_IN(max)× (R1||R2) =

_ERROR= ±1×10^-8A × 2.189×10⁵Ω =

_ERROR= ±2.189×10^-3V =

_ERROR= ±2.189mV

The typical error is about three orders of magnitude lower

than this—close to one microvolt. Generally, the error

due to input bias can be discounted. If it is to be taken

into account, simply adjust the target threshold voltage

downward by this amount and recalculate R1 and R2.

The resulting value will be very close to optimum. If

accuracy is more important than the quiescent current in

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MIC2774

the resistors, simply reduce the value of R_TOTALto

minimize offset errors.

Transient Response

The MIC2774 is inherently immune to very short

negative-going glitches. Very brief transients may exceed

the voltage thresholds without tripping the output.

In general, as shown in Figure 3 and Figure 4, the

narrower the transient, the deeper the threshold overdrive

that the MIC2774 will ignore. The graphs represent the

typical allowable transient duration for a given amount of

threshold overdrive that will not generate a reset.

Figure 1. MIC2774 Example Design

Interfacing to Processors with Bidirectional Reset

Pins

Some microprocessors have reset signal pins that are

bidirectional, rather than input-only. The Motorola

68HC11 family is one example. Because the MIC2774N’s

output is open-drain, it can be connected directly to the

processor’s reset pin using only the pull-up resistor

normally required. See Figure 2.

Figure 3. Typical Input Transient Response

Figure 4. Typical V_DDTransient Response

Ensuring Proper Operation at Low Supply

Figure 2. Interfacing to Bidirectional Reset Pin

At V_DDlevels below 1.2V, the MIC2774’s reset output

cannot turn on sufficiently to produce a valid logic-low on

/RST. In this situation, circuits driven by /RST could be

allowed to float, causing undesired operation. In most

cases, however, it is expected that the circuits driven by

the MIC2774L will be similarly inoperative at V_DD≤ 1.2V.

If a given application requires that /RST be valid below

V_DD= 1.2V, this can be accomplished by adding a pull-

down resistor to the /RST output. A value of 100kΩ is

recommended because this is usually an acceptable

compromise of quiescent current and pull-down current.

The resistor’s value is not critical, however. See Figure 5.

March 16, 2015

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MIC2774

These statements also apply to the MIC2774H’s RST

output. That is, to ensure valid RST signal levels at V_DD

1.2V, a pull-up resistor (as opposed to a pull-down)

should be added to the RST output. A value of 100kΩ is

typical for this application, as well. See Figure 6.

Figure 5. MIC2774L Valid /RST Below 1.2V

Figure 6. MIC2774H Valid RST Below 1.2V

March 16, 2015

Revision 2.0

Micrel, Inc.

MIC2774

Package Information and Recommended Landing Pattern⁽¹⁴⁾

SOT-23-5 (M5)

Note:

14. Package information is correct as of the publication date. For updates and most current information, go to www.micrel.com.

March 16, 2015

Revision 2.0

Micrel, Inc.

MIC2774

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

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.

March 16, 2015

Revision 2.0

MIC2774H-23YM5-TR [MICROCHIP]

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