te c h t m I7990N tm technology inc. reserves the right p. 1 to change products or specifications without notice . c reate I7990N boost converter and current monitor for apd general description the I7990N consists of a constant-frequency pulse-w idth modulating (pwm) step-up dc-dc converter with an internal switch and a curre nt monitor with high-speed adjustable current limiting. this device can generate output v oltages up to 60v and provides current monitoring up to 4ma (up to 240mw). the I7990N can be used for a wide variety of applications such as avalanche photodiode biasing, pin biasing, and varactor biasing. the I7990N operates from 2.8v to 5.5v. the constant-frequency (400khz), pwm architecture p rovides low-noise output voltage that is easy to filter. a high-voltage, int ernal power switch allows this device to boost output voltages up to 60v. internal soft-star t circuitry limits the input current when the boost converter starts. the I7990N features a s hutdown mode to save power. the I7990N includes a current monitor with more tha n three decades of dynamic range and monitors current ranging from 500na to 4m a with high accuracy. resistor- adjustable current limiting protects the apd from o ptical power transients. a clamp diode protects the monitors output from overvoltage cond itions. other protection features include cycle-by-cycle current limiting of the boos t converter switch, undervoltage lockout, and thermal shutdown if the die temperature reaches +150c. applications ? pin/apd biasing supply and monitoring. ? low-noise varactor diode bias supplies. ? sdh/sonet/ethernet/ftth/gpon application. features input voltage range +2.8v to +5.5v wide output-voltage range from (v in +5v) to 60v 240mw boost converter output power accurate 5% (5:1) high-side current monitor resistor-adjustable ultra-fast apd current limit the I7990N is available in a 3mm x 3mm, 16-pin qfn package and operates over the -40c to +85c automotive temperature range. open-drain current-limit indicator flag constant p wm frequency (400khz) provides easy filtering in low-noise applications 2a (max) shutdown current -40c to +85c temperature range internal 1 (typ) 60v switch
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