MIC47050YMT-TR - MICROCHIP TECHNOLOGY

MIC833

Comparator and Reference with Adjustable

Hystersis

Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com

General Description

The MIC833 is a micropower precision dual voltage

comparator with an on-chip reference and latch. High- and

low-voltage thresholds are adjusted independently,

allowing for wide hysteresis. Three external resistors

determine the threshold voltages. Voltage detection

thresholds are accurate to 1.5%. Supply current is

extremely low (1µA, typical), making it ideal for portable

applications.

The MIC833 is supplied in Micrel’s 5-lead SOT-23

package. See the MIC2778 for applications requiring an

output delay.

Data sheets and support documentation can be found on

Micrel’s web site at: www.micrel.com.

Features

• Optimized for PDAs, cellular telephones, pagers, and

other battery-powered devices

• Inputs and output can pulled up to 6V regardless of

supply voltage

• Independently adjustable high- and low-voltage

thresholds

• High ±1.5% voltage threshold accuracy

• Extremely low 1µA typical supply current

• Immune to brief input transients

• 5-lead SOT-23 package

Applications

• PDAs

• Pagers

• Cordless Phones

• Consumer electronics

• Embedded controllers

• Personal electronics

_________________________________________________________________________________________________________________________

Typical Application

July 2012

M9999-070912-B

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Ordering Information

Part Number Marking(1) Accuracy Junction Temperature Range(1) Package

MIC833YM5 B11 1.5% –40° to +85°C SOT-23-5 Pb-Free

Note:

1. Under bar symbol (_) may not be to scale

Pin Configur ation

5-Pin SOT-23 (M5)

Pin Description

Pin Number Pin Name Pin Function

1 HTH

High-Voltage Threshold (Input): Analog input to a comparator. This is the voltage input assigned

to detect a high-voltage condition when the level on this pin exceeds VREF, OUT is asserted and

the condition is latched until VLTH < VREF.

2 GND Ground

3 LTH

Low-Voltage Threshold (Input): Analog input to a comparator. This is the voltage input assigned

to detect a low voltage condition. When the level on this pin falls below VREF, OUT is de-asserted

and the condition is latched until VHTH > VREF.

4 OUT

Output: Active-high, open-drain output. This output is de-asserted and latched when VLTH <VREF,

indicating a low voltage condition. This state remains latched until VHTH > VREF.

5 VDD Power Supply (Input): Independent supply input for internal circuitry.

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Absolute Maximum Ratings(1)

Supply Voltage (VDD)....................................... –0.3V to +7V

Input Voltages (VLTH, VHTH).............................................+7V

Output Current (IOUT) ...................................................20mA

Output Voltage (VOUT) ..................................... −0.3V to +7V

Lead Temperature (soldering, 10s)............................ 260°C

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

ESD Rating(3).................................................................. 2kV

Operating Ratings(2)

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

Input Voltage (VLTH, VHTH) ................................... 0V to +6V

Output Voltage (VOUT) .......................................... 0V to +6V

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

Junction Temperature (TJ) ........................ Internally Limited

Package Thermal Resistance (θJA)........................260°C/W

Electrical Characteristics(4)

1.5V ≤ VDD ≤ 5.5V; TA = 25°C, bold values indicate –40°C≤ TA ≤ +85°C, unless noted.

Symbol Parameter Conditions Min Typ Max Units

IDD Supply Current Outputs not asserted 1 2 µA

ILTH, IHTH Input Leakage Current 0.005 10 nA

VREF Reference Voltage 1.221 1.240 1.259 V

VLTH = 1.352V to 1.128V 5

tD Propagation Delay

VHTH = 1.128V to 1.352V 5 µs

OUT de-asserted, ISINK = 1.6mA, VDD ≥ 1.6V 0.3

VOUT Output Voltage-Low(4)

OUT de-asserted, ISINK = 100µA, VDD ≥ 1.2V 0.4

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, 1.5kΩ in series with 100pF.

4. VDD operating range is 1.5V to 5.5V. Output is guaranteed to be held low down to VDD = 1.2V.

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Functional Diagram

Timing Diagram

Notes:

Note A. Brief transients are ignored by the MIC833. See “Application Information”.

Note B. VLTH > VLO > VREF

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Block Diagram

Functional Description

The MIC833 monitors a voltage and detects when it is

below or above two independently programmed levels.

Voltage Low Output

The output (OUT) is an active-high, open-drain output

which sinks current when the MIC833 detects a low input

voltage at its LTH input. This condition is latched until

the HTH input is presented with a voltage higher than

the internal VREF (+1.24V).

Trip Points

Input voltage is monitored by the comparators via a

voltage divider network. The divided voltage is compared

to an internal reference voltage. When the voltage at the

LTH input pin drops below the internal reference voltage,

the output pulls low. Because of the voltage divider, the

voltage at HTH is assured to be below the reference

voltage.

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Applications Information

Output

Since the MIC833 output is an open-drain MOSFET,

most applications will require a pull-up resistor. The

value of the resistor should not be too large or leakage

effects may dominate. 470kΩ is the maximum

recommended value. Note that the output may be pulled

up as high as 6V regardless of IC supply voltage. See

“Electrical Characteristics.”

Programming the Thresholds

The low-voltage threshold is calculated using:

⎟

⎠

⎞

⎜

⎝

⎛

=R3R2

R3R2R1

VV REFIN(LO) Eq. 1

The high-voltage threshold is calculated using:

⎟

⎠

⎞

⎜

⎝

⎛++

=R3

R3R2R1

VV REFIN(HI) Eq. 2

Where VREF = 1.240V for both equations.

In order to provide the additional criteria needed to solve

for the resistor values, the resistors can be selected

such that they have a given total value, that is, R1 + R2

+ R3 = RTOTAL. A value such as 1MΩ for RTOTAL is a

reasonable value because it draws minimum current but

has no significant effect on accuracy.

When working with large resistors, a small amount of

leakage current can cause voltage offsets that degrade

system accuracy. The maximum recommended total

resistance from VIN to ground is 3MΩ

Figure 1. Example Circuit

Once the desired trip points are determined, set the

VIN(HI) threshold first.

For example, use a total of 1MΩ = R1 + R2 + R3. For a

typical single-cell lithium ion battery, 3.6V is a good “high

threshold” because at 3.6V the battery is moderately

charged. Solving for R3:

⎟

⎠

⎞

⎜

⎝

⎛

== R3

1MΩ

1.243.6VVIN(HI) Eq. 3

where:

R3 = 344kΩ

Once R3 is determined, the equation for VIN(LO) can be

used to determine R2. A single lithium-ion cell, for

example, should not be discharged below 2.5V. Many

applications limit the drain to 3.1V. Using 3.1V for the

VIN(LO) threshold allows calculation of the two remaining

resistor values:

⎟

⎠

⎞

⎜

⎝

⎛

== 344kR2

1MΩ

1.24V3.1VVIN(LO) Eq. 4

where:

R2 = 56kΩ

1MΩ − (R2 − R3) = R1

R1 = 600kΩ

The accuracy of the resistors can be chosen based upon

the accuracy required by the system.

The inputs may be subjected to voltages as high as 6V

steady state without adverse effects of any kind,

regardless of the IC supply voltage. This applies even if

the supply voltage is zero. This permits the situation in

which the IC supply is turned off, but voltage is still

present on the inputs. See “Electrical Characteristics.”

Input Transients

The MIC833 is inherently immune to very short negative

going “glitches.” Very brief transients may exceed the

VIN(LO) threshold without tripping the output.

As shown in Figure 2, the narrower the transient, the

deeper the threshold overdrive that will be ignored by the

MIC833. The graph represents the typical allowable

transient duration for a given amount of threshold

overdrive that will not toggle the output.

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Example Application

The battery charger of Figure 3 uses the MIC833 to

detect a low-battery voltage condition (VDIS) and enables

a constant-current source (ICHG). Charging current is

enabled until a charged-battery voltage condition (VCHG)

is detected; at which time the charging-current source is

disabled.

Diode D1 was added to Figure 3 to ensure the disabled

current source does not draw battery current. Whether or

not D1 is required is a function of the output stage of the

current source and how it is disabled.

The circuitry of Figure 3 is deliberately generalized to

imply flexibility of application. Depending on the

application, it may not be possibly to power the MIC833

from the charger supply voltage, see Note 2. It may be

necessary to provide a separate voltage regulator, or a

resistive voltage divider to reduce the VDD applied to the

MIC833. The part can be supplied by the battery voltage

(VBAT) if this voltage is never lower than 1.5V, the

minimum operating VDD of the part.

Figure 2. Input Transient Respon se

Initialization Behavior

When the MIC833 is powered up, the comparators and

latch become active before the reference voltage

reaches its final value. In most applications, this

presents no problems. However, the user should be

aware of this: when applying power to the part, if the

input voltage is between the two thresholds, the output

of the part will be high because input HTH will have been

higher than the 1.24V reference during initialization.

Voltage thresholds, VDIS and VCHG, are programmed as

described in the appropriate above paragraph.

It is not very likely the part would be powered up in this

state; it is more likely the same power supply will power

the part and develop its inputs. However, if the above-

described condition should occur, the next HTH

threshold crossing would not be processed; that is, the

latch would have been already set. The next valid input

condition would have to be a crossing of the LTH

threshold, which resets the latch, after which “normal”

operation is restored.

Figure 3. Battery Charger

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Package Information

5-Pin SOT-23 (M5)

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 makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this data sheet. 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

reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical impla

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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indemnify Micrel for any damages resulting from such use or sale.

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