Sequencing/Supervisory Circuits

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1 Click here for production status of specific part numbers. MAX1652/MAX1653 General Description The MAX1652/MAX1653 are a family of small, low-power, high-voltage monitoring circuits with sequencing capability. These miniature devices offer very wide flexibility with an adjustable voltage threshold and an external capacitoradjustable time delay. These devices are ideal for use in power-supply sequencing, reset sequencing, and power switching applications. Multiple devices can be cascaded for complex sequencing applications. A high-impedance input () with a.5v threshold allows an external resistive-divider to set the monitored threshold. The output () asserts high when the input voltage rises above the.5v threshold and the enable input () is asserted high. When the voltage at falls below.495v or when the enable input is de-asserted ( = low), the output deasserts ( = low). The devices provide a capacitor programmable delay time from when the voltage at rises above.5v to when the output is asserted. The MAX1652 offers an active-high open-drain output while the MAX1653 offers an active-high pushpull output. Both devices operate from a 2.25V to 28V supply voltage and feature an active-high enable input. The MAX1652/MAX1653 are available in a tiny 6-pin SOT23 package and are fully specified over the automotive temperature range (-4 C to +125 C). Benefits and Features Less External Circuitry Results in Smaller Solution Size Open-Drain (28V Tolerant) Output Allows Interfacing to 12V Intermediate Bus Voltage Operates from of 2.25V to 28V Small 6-Pin SOT23 Package Ideal for Use in Power-Supply Sequencing, Reset Sequencing, and Power-Switching Applications Active-High Logic-Enable Input 1.8% Accurate Adjustable Threshold Over Temperature Fully Specified from -4 C to +125 C for Reliability in Extreme Temperatures Low Supply Current (18µA typ) Reduces Power Consumption Applications Medical Equipment Intelligent Instruments Portable Equipment Computers/Servers Critical μp Monitoring Set-Top Boxes Telecom Typical Operating Circuit DC-DC CONVERTER 12V MAX1652.9V MAX1652 CDELAY DC-DC CONVERTER CDELAY ; Rev 7; 5/18

2 Absolute Maximum Ratings (All voltages referenced to.)...-.3v to +3V (push-pull, MAX1653)...-.3V to ( +.3V) (open-drain, MAX1652)...-.3V to +3V,...-.3V to ( +.3V) CDELAY...-.3V to +6V Input/Output Current (all pins)...±2ma Continuous Power Dissipation (T A = +7 C) 6-Pin SOT23 (derate 8.7mW/ C above +7 C) mW Operating Temperature Range...-4 C to +125 C Junction Temperature C Storage Temperature Range C to +15 C Lead Temperature (soldering, 1s)...+3 C Soldering Temperature (reflow) C Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Electrical Characteristics ( = 2.25V to 28V, V =, T A = T J = -4 C to +125 C, unless otherwise specified. Typical values are at = 3.3V and T A = +25 C.) (Note 1) SUPPLY PARAMETER SYMBOL CONDITIONS M TYP MAX UNITS Operating Voltage Range V Undervoltage Lockout UVLO falling (Note 2) V Supply Current I CC MAX1652, no load MAX1653, no load = 3.3V = 12V = 28V = 3.3V = 12V = 28V Threshold Voltage V TH V rising, 2.25V 28V V Hysteresis V HYST V falling 5 mv Input Current I V = or 28V na C DELAY C DELAY Charge Current I CD V CDELAY = V na C DELAY Threshold V TCD V CDELAY rising V 2.25V, I SK = 2μA 15 6 C DELAY Pulldown Resistance R CDELAY 3.3V, I SK = 1mA 15 6 Low Voltage V IL.5 V High Voltage V IH 1.4 V Leakage Current I LEAK V = or 28V na Low Voltage (Open-Drain or Push-Pull) High Voltage (Push-Pull, MAX1653) Leakage Current (Open-Drain, MAX1652) V OL 2.25V, I SK =.5mA.3 1.2V, I SK = 9μA.2 > 4.5V, I SK = 1mA.4 V OH 2.25V, I SOURCE = 5μA.8 x V 4.5V, I SOURCE = 8μA.9 x I LKG Output not asserted low, V = 28V 15 na µa Ω V Maxim Integrated 2

3 Electrical Characteristics (continued) ( = 2.25V to 28V, V =, T A = T J = -4 C to +125 C, unless otherwise specified. Typical values are at = 3.3V and T A = +25 C.) (Note 1) TIMG PARAMETER SYMBOL CONDITIONS M TYP MAX UNITS to Propagation Delay Startup Delay (Note 3) t DELAY = 3.3V, V rising, V = V TH + 25mV = 12V, V rising, V = V TH + 25mV MAX1652, 1kΩ pullup resistor, C CDELAY = MAX1653, C CDELAY = MAX1652, 1kΩ pullup resistor, C CDELAY =.47μF MAX1653, C CDELAY =.47μF MAX1652, 1kΩ pullup resistor, C CDELAY = MAX1653, C CDELAY = t DL = 3.3V, V falling, V = V TH - 3mV 18 = 12V, V falling, V = V TH - 3mV 18 = 2.25V, V =.525V, C CDELAY =.5 = 12V, V = 12V, C CDELAY =.5 Minimum Input Pulse Width t MPW 1 µs Glitch Rejection 1 ns 3 3 µs ms µs ms to Delay t OFF From device enabled to device disabled MAX1652, 1kΩ pullup resistor MAX1653 = 3.3V 25 = 12V 3 = 3.3V 35 = 12V 4 ns to Delay t PROP From device disabled to device enabled MAX1652, 1kΩ pullup resistor, C CDELAY = MAX1653 MAX1652, 1kΩ pullup resistor, C CDELAY =.47μF MAX1653, C CDELAY =.47μF = 3.3V 14 = 12V 14 = 3.3V 14 = 12V µs ms Note 1: All devices are production tested at T A = +25 C. Limits over temperature are guaranteed by design. Note 2: When falls below the UVLO threshold, the outputs deassert ( goes low). When falls below 1.2V, the output state cannot be determined. Note 3: During the initial power-up, must exceed 2.25V for at least.5ms before can go high. Maxim Integrated 3

4 V UVLO V TH + 25mV V TH - V HYST V TH t < t PROP V IH V IL V IH V IL V IH 5% V IH t < t MPW t > tmpw V OL V OH t PROP t DL t DELAY t OFF t PROP Figure 1. MAX1652/MAX1653 Timing Diagram (C CDELAY = ) Maxim Integrated 4

5 Typical Operating Characteristics ( = 3.3V and T A = +25 C, unless otherwise noted.) ICC (µa) MAX1652 V = V SUPPLY CURRT vs. SUPPLY VOLTAGE (V) MAX1652/53 toc1 ICC (µa) MAX1652 = 12V SUPPLY CURRT vs. TEMPERATURE = 5V = 3.3V 8 = 2.25V TEMPERATURE (C) = 28V MAX1652/53 toc2 THRESHOLD VOLTAGE (mv) THRESHOLD VOLTAGE vs. TEMPERATURE TEMPERATURE (C) MAX1652/53 toc3 DELAY (ms) DELAY vs. C CDELAY C CDELAY (nf) MAX1652/53 toc4 PUT LOW VOLTAGE (V) = 2.25V PUT LOW VOLTAGE vs. SK CURRT = 3.3V = 5V = 12V = 28V MAX1652/53 toc5 PUT HIGH VOLTAGE (V) PUT HIGH VOLTAGE vs. SOURCE CURRT = 28V = 2.25V = 3.3V = 5V = 12V MAX1652/53 toc I SK (ma) I SOURCE (ma) Maxim Integrated 5

6 Typical Operating Characteristics (continued) ( = 3.3V and T A = +25 C, unless otherwise noted.) MAXIMUM TRANSIT DURATION (µs) MAXIMUM TRANSIT DURATION vs. PUT OVERDRIVE RESET OCCURS ABOVE THIS CURVE MAX1652/53 toc7 ABLE TURN-ON DELAY (MAX1653) MAX1652/53 toc8 2V/div 2V/div ABLE TURN-OFF DELAY (MAX1653) MAX1652/53 toc9 2V/div 2V/div PUT OVERDRIVE (mv) 1µs/div 4ns/div LEAKAGE CURRT (na) LEAKAGE CURRT vs. TEMPERATURE = 28V = V = V MAX1652/53 toc1 LEAKAGE CURRT (na) = 28V = V LEAKAGE CURRT vs. VOLTAGE MAX1652/53 toc TEMPERATURE ( C) V (V) LEAKAGE CURRT (na) LEAKAGE CURRT vs. TEMPERATURE = 28V = V = V MAX1652/53 toc12 LEAKAGE CURRT (na) = 28V = V LEAKAGE CURRT vs. VOLTAGE MAX1652/53 toc TEMPERATURE ( C) V (V) Maxim Integrated 6

7 Pin Configuration TOP VIEW 1 C DELAY 6 MAX1652 MAX SOT23 Pin Description P NAME FUNCTION 1 2 Ground 3 Active-High Logic-Enable Input. Drive low to immediately de-assert the output to its false state ( = low) independent of V. With V above V TH, drive high to assert the output to its true state ( = high) after the adjustable delay period. Connect to, if not used. High-Impedance Monitor Input. Connect to an external resistive-divider to set the desired monitor threshold. The output changes state when V rises above.5v and when V falls below.495v. 4 Active-High Sequencer/Monitor Output. Open-drain (MAX1652) or push-pull (MAX1653). is asserted to its true state ( = high) when V is above V TH and the enable input is in its true state ( = high) after the capacitor-adjusted delay period. is de-asserted to its false state ( = low) immediately after V drops below.495v or the enable input is in its false state ( = low). The MAX1652 open-drain output requires an external pullup resistor. 5 Supply Voltage Input. Connect a 2.25V to 28V supply to to power the device. For noisy systems, bypass with a.1μf ceramic capacitor to. 6 C DELAY to set the -to- and -to- delay period. For V rising, t DELAY = (C CDELAY x 4. x 16) + Capacitor-Adjustable Delay Input. Connect an external capacitor (C CDELAY ) from C DELAY to 3μs. For rising, t PROP = (C CDELAY x 4. x 1 6 ) + 14μs. Maxim Integrated 7

8 REF TERNAL /UVLO REF TERNAL /UVLO.5V CONTROL LOGIC.5V CONTROL LOGIC 25nA 25nA 1.V 1.V MAX1652 MAX1653 CDELAY CDELAY Figure 2. Simplified Functional Diagram Detailed Description The MAX1652/MAX1653 family of high-voltage, sequencing/supervisory circuits provide adjustable voltage monitoring for inputs down to.5v. These devices are ideal for use in power-supply sequencing, reset sequencing, and power-switching applications. Multiple devices can be cascaded for complex sequencing applications. The MAX1652/MAX1653 perform voltage monitoring using a high-impedance input () with an internally fixed.5v threshold. When the voltage at falls below.5v or when the enable input is de-asserted ( = low) goes low. When V rises above.5v and the enable input is asserted ( = high), goes high after a capacitor-adjustable time delay. With V above.5v, the enable input can be used to turn on or off the output. Table 1 details the output state depending on the various input and enable conditions. Table 1. MAX1652/MAX1653 V < V TH Low Low V < V TH High Low V < V TH Low Low V > V TH High = High Impedance (MAX1652) = (MAX1653) Supply Input ( ) The device operates with a supply voltage from 2.25V to 28V. In order to maintain a 1.8% accurate threshold at, must be above 2.25V. When falls below the UVLO threshold, the output deasserts low. When falls below 1.2V, the output state is not guaranteed. For noisy systems, connect a.1μf ceramic capacitor from to as close to the device as possible. Maxim Integrated 8

9 Monitor Input () Connect the center point of a resistive-divider to to monitor external voltages (see R1 and R2 of Figure 4). has a rising threshold of V TH =.5V and a falling threshold of.495v (5mV hysteresis). When V rises above V TH and is high, goes high after the adjustable t DELAY period. When V falls below.495v, goes low after a 18μs delay. has a maximum input current of 6nA, so large value resistors are permitted without adding significant error to the resistive-divider. Adjustable Delay (CDELAY) When V rises above V TH with high, the internal 25nA current source begins charging an external capacitor connected from C DELAY to. When the voltage at C DELAY reaches 1V, the output asserts ( goes high). When the output asserts, C CDELAY is immediately discharged. Adjust the delay (t DELAY ) from when V rises above V TH (with high) to going high according to the equation: t 6 DELAY = C CDELAY (4 1 Ω ) + (3µs) where t DELAY is in seconds and C CDELAY is in Farads. Enable Input () The MAX1652/MAX1653 offer an active-high enable input (). With V above V TH, drive high to force high after the capacitor-adjustable delay time. The -to- delay time (t PROP ) can be calculated from when goes above the threshold using the equation: t 6 PROP = C CDELAY (4 1 Ω ) + (14µs) where t PROP is in seconds and C CDELAY is in Farads. Drive low to force low within 3ns for the MAX1652 and within 4ns for the MAX1653. Output () The MAX1652 offers an active-high, open-drain output while the MAX1653 offers an active-high push-pull output. The push-pull output is referenced to. The open-drain output requires a pullup resistor and can be pulled up to 28V. Applications Information Input Threshold The MAX1652/MAX1653 monitor the voltage on with an external resistive-divider (Figure 4). R1 and R2 can have very high values to minimize current consumption due to low leakage currents (6nA max). Set R2 to some conveniently high value (2kΩ for ±1% additional variation in threshold, for example) and calculate R1 based on the desired monitored voltage using the following formula: V R1 R2 MONITOR = 1 VTH where V MONITOR is the desired monitored voltage and V TH is the reset input threshold (.5V). Pullup Resistor Values (MAX1652 Only) The exact value of the pullup resistor for the open-drain output is not critical, but some consideration should be made to ensure the proper logic levels when the device is sinking current. For example, if = 2.25V and the pullup voltage is 28V, keep the sink current less than.5ma as shown in the Electrical Characteristics table. As a result, the pullup resistor should be greater than 56kΩ. For a 12V pullup, the resistor should be larger than 24kΩ. Note that the ability to sink current is dependent on the supply voltage. Ensuring a Valid Down to = V (Push-Pull ) In applications in which must be valid down to = V, add a pulldown resistor between and for the push-pull output (MAX1653). The resistor sinks any stray leakage currents, holding low (Figure 3). The value of the pulldown resistor is not critical; 1kΩ is large enough not to load and small enough to pull to ground. The external pulldown cannot be used with the open-drain output. MAX1653 Figure 3. Ensuring Valid to = V 1kΩ Maxim Integrated 9

10 Typical Application Circuits Figure 4 through Figure 6 show typical applications for the MAX1652/MAX1653. Figure 4 shows the MAX1652 used with a pmosfet in an overvoltage protection circuit. Figure 5 shows the MAX1653 in a low-voltage sequencing application using an nmosfet. Figure 6 shows the MAX1653 used in a multiple output sequencing application. Using an n-channel Device for Sequencing In higher power applications, using an n-channel device reduces the loss across the MOSFET as it offers a lower drain-to-source on-resistance. However, an nmosfet requires a sufficient V GS voltage to fully enhance it for a low R DS_ON. The application shown in Figure 5 shows the MAX1653 in a switch sequencing application using an nmosfet. Similarly, if a higher voltage is present in the system, the open-drain version can be used in the same manner. Power-Supply Bypassing In noisy applications, bypass to ground with a.1μf capacitor as close to the device as possible. The additional capacitor improves transient immunity. For fast-rising transients, additional capacitors may be required. TO 28V 3.3V ALWAYS-ON R PULLUP P MONITORED 3.3V 5V BUS 1.2V PUT N 1.2V PUT R1 R1 MAX1652 MAX1653 C DELAY C DELAY R2 C CDELAY R2 C CDELAY Figure 4. Overvoltage Protection Figure 5. Low-Voltage Sequencing Using an nmosfet Maxim Integrated 1

11 3.3V 2.5V 1.8V 1.2V 5V BUS DC-DC DC-DC DC-DC DC-DC SYSTEM ABLE MAX1653 MAX1653 MAX1653 MAX1653 C CDELAY C CDELAY C CDELAY C CDELAY Figure 6. Multiple Output Sequencing Ordering Information PART PUT P- PACKAGE TOP MARK MAX1652AUT+T Open-Drain 6 SOT23 +ACLW MAX1653AUT+T Push-Pull 6 SOT23 +ACLX Note: All devices operate over the -4 C to +125 C operating automotive temperature range. +Denotes a lead(pb)-free/rohs-compliant package. T = Tape and reel, offered in 2.5k increments. Package Information For the latest package outline information and land patterns (footprints), go to Note that a +, #, or - in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE PACKAGE CODE LE NO. LAND PATTERN NO. 6 SOT23 U Chip Information PROCESS: BiCMOS Maxim Integrated 11

12 Revision History REVISION NUMBER REVISION DATE DESCRIPTION PAGES CHANGED 5/8 Initial release 1 1/8 Update Adjustable Delay (CDELAY) and Power-Supply Bypassing sections. 9, 1 2 1/1 Revised the Features, General Description, Absolute Maximum Ratings, Electrical Characteristics, Typical Operating Characteristics, Pin Description, and the Supply Input (VCC) sections. 1, 2, 3, /14 No /V OPNs; removed Automotive reference from Applications section 1 4 5/15 Added the Benefits and Features section 1 5 3/16 Updated package outline drawing number in Ordering Information table /16 Updated Table /18 Updated TOC1 6 For pricing, delivery, and ordering information, please contact Maxim Direct at , or visit Maxim Integrated s website at Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc. 218 Maxim Integrated Products, Inc. 12