MAXIM Manuals

The MAX6832-MAX6840 are microprocessor (µP) supervisory circuits used to monitor low-voltage power supplies in µP and digital systems. They provide excellent circuit reliability and low cost by eliminating external components and adjustments when used with +1.2V to +1.8V powered circuits. These devices assert a reset signal whenever the VCC supply voltage declines below a preset threshold or whenever manual reset (MR) is asserted. Reset remains asserted for a fixed timeout delay after VCC has risen above the reset threshold or when manual reset is deasserted. Five different timeout periods are available: 70µs (voltage detector), 1.5ms, 30ms, 210ms, and 1.68s. Reset thresholds suitable for operation with a variety of supply voltages are available. The MAX6832/MAX6835/MAX6838 have a push-pull active-low reset output (RESET). The MAX6833/MAX6836/MAX6839 have a push-pull active-high reset output (RESET) and the MAX6834/MAX6837/MAX6840 have an open-drain active-low reset output (RESET). The open-drain active-low reset output requires a pullup resistor that can be connected to a voltage higher than VCC. The MAX6835/MAX6836/MAX6837 feature a debounced manual reset input (MR), while the MAX6838/MAX6839/MAX6840 provide a RESET-IN input allowing the user to externally adjust the reset threshold. The reset comparator is designed to ignore fast transients on VCC. Low supply current of 7.5µA makes the MAX6832-MAX6840 ideal for use in portable equipment.

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MAX4060/MAX4061/MAX4062 is a differential-input microphone preamplifier optimized for notebook and PDA audio systems. These devices feature adjustable gain with excellent power-supply rejection and com- mon-mode rejection ratios, making them ideal for low- noise applications in portable audio systems

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The MAX2645 evaluation kit is a simple-to-use evaluation board that can be used to evaluate the MAX2645 3.4GHz to 3.8GHz low-noise amplifier/PA predriver. The evaluation kit is fully assembled and tested, allowing easy evaluation of all device functions. All RF signal ports use SMA connectors, providing a convenient interface to RF test equipment. The MAX2645 is a versatile, high-performance, low-noise amplifier with adjustable IP3. These features allow the MAX2645 to be used in a variety of applications, from a low-noise amplifier to a PA predriver. As assembled, the MAX2645 evaluation kit is configured for lowest noise figure performance (NF = 2.3dB, IIP3 = +4dBm). A few minor component changes configure the device as a low-noise amplifier with higher linearity and slightly degraded noise figure performance (NF = 2.6dB, IIP3 = +10dBm) or as a PA predriver with high output P1dB performance (output P1dB = +12dBm). Refer to the MAX2645 data sheet for application-specific performance data.

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The MAX1765 is a high-efficiency, low-noise, step-up DC-DC converter intended for use in battery-powered wireless applications. This device operates at a high 1MHz fixed frequency while maintaining an exception- ally low quiescent supply current (200µA). Its small external components and tiny package make this device an excellent choice for small hand-held applica- tions that require the longest possible battery life. The MAX1765 uses a synchronous-rectified pulse- width-modulation (PWM) boost topology to generate 2.5V to 5.5V outputs from a wide range of input sources, such as one to three alkaline or NiCd/NiMH cells or a single lithium-ion (Li+) cell. Maxim's propri- etary architecture significantly improves efficiency at low load currents while automatically transitioning to fixed-frequency PWM operation at medium to high load currents to maintain excellent full-load efficiency. Forced-PWM mode is available for applications that require constant-frequency operation at all load cur- rents, and the MAX1765 may also be synchronized to an external clock to protect sensitive frequency bands in communications equipment. The MAX1765’s low-dropout (LDO) linear regulator and DC-DC converter have separate shutdown control. The linear regulator's 250mΩ pass device maintains excel- lent dropout voltage at currents up to 500mA. The MAX1765 also features analog soft-start and current- limit functions to permit optimization of efficiency, exter- nal component size, and noise.

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The MAX987/MAX988/MAX991/MAX992/MAX995/MAX996 single/dual/quad micropower comparators feature low-voltage operation and Rail-to-Rail inputs and outputs. Their operating voltage ranges from +2.5V to +5.5V, making them ideal for both 3V and 5V systems. These comparators also operate with ±1.25V to ±2.75V dual supplies. They consume only 48µA per comparator while achieving a 120ns propagation delay. The common-mode input voltage range extends 250mV beyond the supply rails. Input bias current is typically 1.0pA, and input offset voltage is typically 0.5mV. Internal hysteresis ensures clean output switching, even with slow-moving input signals. The output stage’s unique design limits supply-current surges while switching, virtually eliminating the supply glitches typical of many other comparators. This design also minimizes overall power consumption under dynamic conditions. The MAX987/MAX991/MAX995 have a push/pull output stage that sinks as well as sources current. Large internal output drivers allow rail- to-rail output swing with loads up to 8mA. The MAX988/MAX992/MAX996 have an open-drain output stage that can be pulled beyond VCC to 6V (max) above VEE. These open-drain versions are ideal for level translators and bipolar to single-ended converters. The single MAX987/MAX988 are available in tiny 5-pin SOT23 packages.

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MAX8667/MAX8668 1.5MHz Dual Step-Down DC-DC Converters with Dual LDOs and Individual Enables

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MAX3669 is a 3.3V laser driver with automatic power control (APC) circuitry from MAXIM company. It is suitable for SDH/SONET applications with a bandwidth of up to 622Mbps. The device uses differential PECL inputs, provides bias and modulation currents, and operates over a temperature range of -40°C to +85°C. The built-in APC feedback loop maintains a constant average optical power over temperature and lifetime. This device has a wide modulation current range from 5mA to 75mA and a bias current of 1mA to 80mA, which are easy to program, making it ideal for use in various SDH/SONET applications. MAX3669 also provides enable control and a failure-monitor output to indicate when the APC loop is unable to maintain the average optical power. The device is available in a 5mm 32-pin TQFP package as well as in dice.

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The MAX148/MAX149 are 10-bit data acquisition systems that combine an 8-channel multiplexer, high-bandwidth track/hold, and serial interface with high conversion speed and low power consumption. They operate from a single +2.7V to +5.25V supply, and sample at up to 133ksps. Both devices' analog inputs are software configurable for unipolar/bipolar and single-ended/differential operation. The 4-wire serial interface connects directly to SPI™/QSPI™ and MICROWIRE™ devices without external logic. A serial-strobe output allows direct connection to TMS320-family digital signal processors. The MAX148/MAX149 use either the internal clock or an external serial-interface clock to perform successive-approximation analog-to-digital conversions. The MAX149 has an internal 2.5V reference, while the MAX148 requires an external reference. Both parts have a reference-buffer amplifier with a ±1.5% voltage-adjustment range. These devices provide a hard-wired SHDN pin and a software-selectable power-down, and can be pro-grammed to automatically shut down at the end of a con- version. Accessing the serial interface automatically powers up the MAX148/MAX149, and the quick turn-on time allows them to be shut down between all conver- sions. This technique can cut supply current to under 60µA at reduced sampling rates. The MAX148/MAX149 are available in a 20-pin DIP and a 20-pin SSOP. For 4-channel versions of these devices, see the MAX1248/MAX1249 data sheet.

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The DS1673 is an integrated circuit that incorporates many of the functions necessary for low-power portable products into a single chip. The device provides a real-time clock (RTC), NV RAM controller, microprocessor monitor, and a 3-channel, 8-bit analog-to-digital converter (ADC). Communication with the DS1673 is established through a simple 3-wire interface. The RTC provides seconds, minutes, hours, day, date, month, and year information with leap year compensation. The RTC also provides an alarm interrupt. This interrupt works when the DS1673 is powered by the system power supply or when in battery-backup operation, so the alarm can be used to wake up a system that is powered down. Automatic backup and write protection of an external SRAM is provided through the VCCO, CEOL, and CEOH pins. The backup energy source used to power the RTC is also used to retain RAM data in the absence of VCC through the VCCO pin. The chip- enable outputs to RAM (CEOL and CEOH) are controlled during power transients to prevent data corruption.

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The MAX8887/MAX8888 low-dropout linear regulators operate from a 2.5V to 5.5V input and deliver up to 300mA continuous (500mA pulsed) current. The MAX8887 is optimized for low-noise operation, while the MAX8888 includes an open-drain POK output flag. Both regulators feature exceptionally low 100mV dropout at 200mA. These devices are available in a variety of pre-set output voltages in the 1.5V to 3.3V range. An internal PMOS pass transistor allows the low 55µA supply current to remain independent of load, making these devices ideal for portable battery-powered equip- ment such as personal digital assistants (PDAs), cellu- lar phones, cordless phones, and notebook computers. Other features include a micropower shutdown mode, short-circuit protection, thermal shutdown protection, and an active-low open-drain power-OK (POK) output that indicates when the output is out of regulation. The MAX8887/MAX8888 are available in a thin 5-pin SOT23 package that is only 1mm high.

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The MAX823/MAX824/MAX825 microprocessor (μP) supervisory circuits combine reset output, watchdog, and manual reset input functions. They significantly improve system reliability and accuracy compared to separate ICs or discrete components. The MAX823/MAX824/MAX825 are specifically designed to ignore fast transients on VCC. Seven preprogrammed reset threshold voltages are available. All three devices have an active-low reset output, which is guaranteed to be in the correct state for VCC down to 1V. The MAX823 also offers a watchdog input and manual reset input. The MAX824 offers a watchdog input and a complementary active-high reset. The MAX825 offers a manual reset input and a complementary active-high reset.

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The MAX690A/MAX692A/MAX802L/MAX802M/MAX805L are microprocessor supervisory circuits that reduce complexity and reduce the number of components required for power supply monitoring and battery control functions in µP systems. They significantly improve system reliability and accuracy compared to separate ICs or discrete components.

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MAX6846–MAX6849 is an ultra-low power battery monitor with integrated microprocessor (µP) supervisors. The user-adjustable battery monitors are offered with single or dual low-battery output options that can be used to signal when the battery is OK (enabling full system operation), when the battery is low (for low- power system operation), and when the battery is dead (to disable system operation).

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The MAX6427-MAX6438 are single/dual-level battery monitors with internal hysteresis. These devices are offered with single (MAX6427/MAX6428/MAX6429, MAX6433/ MAX6434/MAX6435) or dual (MAX6430/MAX6431/ MAX6432, MAX6436/MAX6437/MAX6438) low-battery output indicators, which can be used to indicate three battery conditions: battery is good (operate system in normal mode), battery is weak (operate system in low-power mode), or battery is empty (disable the system). These devices are ideal for monitoring single lithium-ion (Li+) cells or multicell alkaline/NiCd/NiMH power supplies. When the power-supply voltage drops below the specified low threshold, the low-battery output asserts. When the voltage rises above the specified high threshold, the low- battery output is deasserted following a 140ms minimum timeout period. The timeout period ensures that the supply voltages have stabilized before power-converter or micro- processor activity is enabled. The MAX6427–MAX6438 family is available with several monitoring options. The MAX6427/MAX6428/MAX6429 offer factory-trimmed battery-monitor thresholds, with a single low-battery output. The MAX6430/MAX6431/MAX6432 also feature factory-trimmed thresholds, but have two low- battery outputs. The MAX6433–MAX6438 have user-adjustable threshold voltages permitting the user to select the hysteresis range, and consequently the sensitivity of the system to noise. A wide hysteresis range also prevents chattering that can result in frequent power-converter or micro-controller switching.

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The MAX6361/MAX6363/MAX6364 supervisory circuits reduce the complexity and number of components required for power-supply monitoring and battery control functions in microprocessor (µP) systems. The circuits significantly improve system reliability and accuracy compared to that obtainable with separate ICs or discrete components. Their functions include µP reset, backup-battery switchover, and power failure warning. The MAX6361/MAX6363/MAX6364 operate from supply voltages as low as +1.2V. The factory preset reset threshold voltage ranges from 2.32V to 4.63V (see Ordering Information). These devices provide a manual reset input (MAX6361), battery-on output (MAX6363), and an auxiliary adjustable reset input (MAX6364). In addition, each part type is offered in three reset output versions: an active-low push-pull reset, an active-low open-drain reset, and an active-high push-pull reset (see Selector Guide at end of data sheet).

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The MAX4178/MAX4278 are ±5V, wide-bandwidth, fast-settling, closed-loop buffers featuring high slew rate, high precision, high output current, low noise, and low differential gain and phase errors. The MAX4178, with a -3dB bandwidth of 330MHz, is preset for unity voltage gain (0dB). The MAX4278 is preset for a voltage gain of +2 (6dB) and has a 310MHz -3dB bandwidth. The MAX4178/MAX4278 feature the high slew rate and low power that are characteristic of current-mode feedback amplifiers. However, unlike conventional current-mode feedback amplifiers, these devices have a unique input stage that combines the benefits of cur- rent-feedback topology with those of the traditional volt- age-feedback topology. This combination results in low input offset voltage and bias current, low noise, and high gain precision and power-supply rejection. The MAX4178/MAX4278 are ideally suited for driving 50Ω or 75Ω loads. They are the perfect choice for high-speed cable-driving applications, such as video routing. The MAX4178/MAX4278 are available in DIP, SO, and space-saving µMAX and SOT23 packages.

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