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MIC834
Micrel
MIC834
Comparator with Reference Advance Information
General Description
The MIC834 is a micropower, precision voltage comparator with an on-chip voltage reference. The threshold is adjusted by the choice of two external resistors. Voltage detection threshold is accurate to 1%. Supply current is extremely low (1.5A, typical), making it ideal for portable applications. The MIC834 is supplied in Micrel's IttyBittyTM 5-lead SOT-235 package.
Features
* Optimized for PDAs, cellular telephones, pagers, and other battery-powered devices * Input and output can be pulled up to 6V regardless of supply voltage * High 1% voltage threshold accuracy * Built in hysteresis for noise suppression * Extremely low 1.5A typical supply current * Immune to brief input transients * 5-lead SOT-23 package
Applications
* * * * * * PDAs Pagers Cordless phones Consumer electronics Embedded controllers Personal electronics
Ordering Information
Part Number MIC834BM5 Marking B12 Accuracy 1% Temperature Range -40C to +85C Package SOT-23-5
Typical Application
VIN VDD MIC834 R1
5
VPULL-UP RPU
4
VDD INP
OUT GND
VOUT VREF = 1.24V VINP(max) = 6V VPULL-UP(max) = 6V 1.5V VDD 5.5V
1
2
R2
IttyBittyTM is a trademark of Micrel, Inc. Micrel, Inc. * 1849 Fortune Drive * San Jose, CA 95131 * USA * tel + 1 (408) 944-0800 * fax + 1 (408) 944-0970 * http://www.micrel.com
April 2000
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MIC834
MIC834
Micrel
Pin Configuration
NC GND INP
3 2 1
4
5
OUT
VDD
SOT-23-5 (M5)
Pin Description
Pin Number 1 2 3 4 Pin Name INP GND NC OUT Pin Function Input: Analog input to the comparator. When VINP > VREF + VHYST, VOUT is asserted to a logic-high level output. Ground No Connect Output: Active-high, open-drain output. This output is de-asserted when VINP < VREF, indicating a low voltage input. The output is asserted when VINP > VREF + VHYST. Power Supply (Input): Independent supply input for internal circuitry.
5
VDD
MIC834
2
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MIC834
Micrel
Absolute Maximum Ratings (Note 1)
Supply Voltage (VDD) ..................................... -0.3V to +7V Input Voltage (VINP) ...................................................... +7V Output Current (IOUT) ................................................. 20mA Storage Temperature (TS) ....................... -65C to +150C ESD Rating, Note 3 ...................................................... 2kV
Operating Ratings (Note 2)
Supply Voltage (VDD) .................................. +1.5V to +5.5V Input Voltage (VINP) ......................................... -0.3V to 6V Ambient Temperature Range (TA) ............. -40C to +85C Junction Temperature (TJ) ....................... Internally Limited Package Thermal Resistance (JA) ...................... 260C/W
Electrical Characteristics
1.5V VDD 5.5V; TA = +25C, bold values indicate -40C TA +85C; unless noted Symbol IDD IINP VREF VHYST tD VOUT Parameter Supply Current Input Leakage Current Reference Voltage Hysteresis Voltage, Note 4 Propagation Delay VINP = 1.352V to 1.128V VINP = 1.143V to 1.367V Output Voltage-Low, Note 5 OUT de-asserted, ISINK = 1.6mA, VDD 1.6V OUT de-asserted, ISINK = 100A, VDD 1.2V,
Note 1. Note 2. Note 3. Note 4. Note 5. Exceeding the absolute maximum rating may damage the device. The device is not guaranteed to function outside its operating rating. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF. VHTH = VREF + VHYST. VDD operating range is 1.5V to 5.5V. Output is guaranteed to be held low down to VDD = 1.2V.
Condition output not asserted
Min
Typ 1.5 0.005
Max 3 10 1.252 35
Units A nA V mV s s
1.228 10
1.240 23 12 8 0.05 0.005
0.3 0.4
V V
Functional Diagram
VIN (Note A) VHTH VREF 0V VPULL-UP VOUT 0V
Note A. VIN here represents the attenuated input voltage, as applied to the INP pin; i.e., VINP. Note B. Brief transients are ignored by the MIC834. See "Applications Information."
Note B Note B
tD
tD
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MIC834
MIC834
Micrel
Block Diagram
VIN VDD
5
VDD
INP VTH
1
High-Voltage Detect OUT
4
1.24V Bandgap Reference MIC834
2
GND
Functional Description
The MIC834 monitors the input voltage and detects when it is higher than a programmed level (plus VHYST). This condition asserts the active-high output. An external pull-up resistor is used to produce a logic-one output. When the input voltage falls below the programmed threshold (VINP < VREF), the output stage is on. Voltage Low Output The voltage-low output (OUT) is an active-high, open-drain output which sinks current when the MIC834 detects a low input voltage.
Trip Points Input voltage is monitored by a comparator via a voltage divider network. The divided voltage is compared to an internal reference voltage. When the voltage at the input pin INP exceeds the internal reference voltage (plus VHYST), the output is pulled high by an external resistor. VHYST is typically 23mV, and is added to the programmed threshold voltage for positive-going inputs. Decreasing inputs trip at the user-programmed threshold voltage. The tolerance of the switching threshold on the falling edge is equal to the tolerance of just the voltage reference. The tolerance of the switching threshold on the rising edge is equal to the tolerance of the voltage reference plus the tolerance of the hysteresis voltage.
MIC834
4
April 2000
MIC834
Micrel
VIN
Applications Information
Output Since the MIC834 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. 470k is the maximum recommended value. Note that the output may be pulled up as high as 6V regardless of the IC's supply voltage. See "Electrical Characteristics." Programming the Threshold The voltage threshold is calculated using: VIN(lo) where: R1 + R2 = VREF R2
MIC834 R1
5
470k
4
VDD INP
OUT GND
VOUT
1
2
R2
Figure 1. Example Circuit Input Transients The MIC834 is inherently immune to very short negativegoing "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 MIC834. The graph represents the typical allowable transient duration for a given amount of threshold overdrive that will not generate an output.
MAX. TRANSIENT DURATION (s)
140 120 100 80 60 40 20 0 1 10 100 1000
VREF = 1.240V
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 = RTOTAL. A value such as 1M 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 3M. 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 steadystate without adverse effects of any kind regardless of the IC's supply voltage. This applies even if the supply voltage is zero. This permits the situation in which the IC's supply is turned off, but voltage is still present on the inputs. See "Electrical Characteristics."
Input Transient Response
RESET COMP. OVERDRIVE, VREF-VLTH (mV)
Figure 2. Input Transient Response
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5
MIC834
MIC834
Micrel
Package Information
1.90 (0.075) REF 0.95 (0.037) REF
1.75 (0.069) 1.50 (0.059)
3.00 (0.118) 2.60 (0.102)
DIMENSIONS: MM (INCH) 3.02 (0.119) 2.80 (0.110) 1.30 (0.051) 0.90 (0.035) 10 0 0.15 (0.006) 0.00 (0.000) 0.20 (0.008) 0.09 (0.004)
0.50 (0.020) 0.35 (0.014)
0.60 (0.024) 0.10 (0.004)
5-Pin SOT (M)
MIC834
6
April 2000
MIC834
Micrel
April 2000
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MIC834
MIC834
Micrel
MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131
TEL
USA
+ 1 (408) 944-0800
FAX
+ 1 (408) 944-0970
WEB
http://www.micrel.com
This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc. (c) 2000 Micrel Incorporated
MIC834
8
April 2000

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