The MAX8520/MAX8521 are designed to drive thermoelectric coolers (TECs) in space-constrained optical modules. Both devices deliver ±1.5A output current and control the TEC current to eliminate harmful current surges. On-chip FETs minimize external components and high switching frequency reduces the size of external components.
The MAX8520/MAX8521 operate from a single supply and bias the TEC between the outputs of two synchronous buck regulators. This operation allows for temperature control without "dead zones" or other nonlinearities at low current. This arrangement ensures that the control system does not hunt when the set-point is very close to the natural operating point, requiring a small amount of heating or cooling. An analog control signal precisely sets the TEC current.
Both devices feature accurate, individually-adjustable heating current limit and cooling current limit along with maximum TEC voltage limit to improve the reliability of optical modules. An analog output signal monitors the TEC current. A unique ripple cancellation scheme helps reduce noise.
The MAX8520 is available in a 5mm x 5mm thin QFN package and its switching frequency is adjustable up to 1MHz through an external resistor. The MAX8521 is also available in a 5mm x 5mm thin QFN as well as space-saving 3mm x 3mm UCSP™ and 36-bump WLP (3mm x 3mm) packages, with a pin-selectable switching frequency of 500kHz or 1MHz.
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