MIC834 Micrel MIC834 Comparator with Reference Advance Information General Description Features 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%. • 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 1.5µA typical supply current • Immune to brief input transients • 5-lead SOT-23 package Supply current is extremely low (1.5µA, typical), making it ideal for portable applications. The MIC834 is supplied in Micrel’s IttyBitty™ 5-lead SOT-235 package. Applications • • • • • • PDAs Pagers Cordless phones Consumer electronics Embedded controllers Personal electronics Ordering Information Part Number Marking Accuracy Temperature Range Package MIC834BM5 B12 1% –40°C to +85°C SOT-23-5 Typical Application VIN VDD VPULL-UP MIC834 R1 5 1 VDD OUT INP GND R2 RPU 4 2 VOUT VREF = 1.24V VINP(max) = 6V VPULL-UP(max) = 6V 1.5V ≤ VDD ≤ 5.5V IttyBitty™ 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 1 MIC834 MIC834 Micrel Pin Configuration NC GND INP 3 2 1 4 5 OUT VDD SOT-23-5 (M5) Pin Description Pin Number Pin Name 1 INP Input: Analog input to the comparator. When VINP > VREF + VHYST, VOUT is asserted to a logic-high level output. 2 GND Ground 3 NC 4 OUT 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. 5 VDD Power Supply (Input): Independent supply input for internal circuitry. MIC834 Pin Function No Connect 2 April 2000 MIC834 Micrel Absolute Maximum Ratings (Note 1) Operating Ratings (Note 2) Supply Voltage (VDD) ..................................... –0.3V to +7V Input Voltage (VINP) ...................................................... +7V Output Current (IOUT) ................................................. 20mA Storage Temperature (TS) ....................... –65°C to +150°C ESD Rating, Note 3 ...................................................... 2kV Supply Voltage (VDD) .................................. +1.5V to +5.5V Input Voltage (VINP) ......................................... –0.3V to 6V Ambient Temperature Range (TA) ............. –40°C to +85°C Junction Temperature (TJ) ....................... Internally Limited Package Thermal Resistance (θJA) ...................... 260°C/W Electrical Characteristics 1.5V ≤ VDD ≤ 5.5V; TA = +25°C, bold values indicate –40°C ≤ TA ≤ +85°C; unless noted Symbol Parameter Condition IDD Supply Current output not asserted IINP Input Leakage Current VREF Reference Voltage VHYST Hysteresis Voltage, Note 4 tD Propagation Delay VOUT Output Voltage-Low, Note 5 Min Typ Max Units 1.5 3 µA 0.005 10 nA 1.228 1.240 1.252 V 10 23 35 mV VINP = 1.352V to 1.128V 12 µs VINP = 1.143V to 1.367V 8 µs OUT de-asserted, ISINK = 1.6mA, VDD ≥ 1.6V 0.05 0.3 V OUT de-asserted, ISINK = 100µA, VDD ≥ 1.2V, 0.005 0.4 V Note 1. Exceeding the absolute maximum rating may damage the device. Note 2. The device is not guaranteed to function outside its operating rating. Note 3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF. Note 4. VHTH = VREF + VHYST. Note 5. VDD operating range is 1.5V to 5.5V. Output is guaranteed to be held low down to VDD = 1.2V. Functional Diagram VIN (Note A) VHTH VREF Note B Note B 0V VPULL-UP tD tD 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.” April 2000 3 MIC834 MIC834 Micrel Block Diagram VDD VIN 5 High-Voltage Detect INP VTH VDD OUT 1 4 1.24V Bandgap Reference MIC834 2 GND 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. 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. 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. 470kΩ 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) MIC834 R1 5 1 OUT INP GND 4 VOUT 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. R1 + R2 = VREF R2 where: 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. VREF = 1.240V MAX. TRANSIENT DURATION (µs) 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 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. 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.” April 2000 470k VDD Input Transient Response 140 120 100 80 60 40 20 0 1 10 100 1000 RESET COMP. OVERDRIVE, VREF–VLTH (mV) Figure 2. Input Transient Response 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) 0.50 (0.020) 0.35 (0.014) 1.30 (0.051) 0.90 (0.035) 0.20 (0.008) 0.09 (0.004) 10° 0° 0.15 (0.006) 0.00 (0.000) 0.60 (0.024) 0.10 (0.004) 5-Pin SOT (M) MIC834 6 April 2000 MIC834 April 2000 Micrel 7 MIC834 MIC834 Micrel MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 TEL + 1 (408) 944-0800 FAX + 1 (408) 944-0970 WEB USA 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. © 2000 Micrel Incorporated MIC834 8 April 2000