MAX8521 datasheet(9/18 Pages) MAXIM

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Smallest TEC Power Drivers for Optical

Modules

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TQFN

UCSP

NAME

FUNCTION

CTLI

TEC Current-Control Input. Sets TEC current. Center point is 1.50V (no TEC current). The

current is given by:

ITEC = (VOS1 - VCS) / RSENSE = (VCTLI - 1.50) / (10 x RSENSE). When (VCTLI - VREF) > 0

then VOS2 > VOS1 > VCS.

GND

Analog Ground. Star connect to PGND at underside exposed pad for TQFN package.

VDD

Analog Supply Voltage Input. Bypass VDD to GND with a 1µF ceramic capacitor.

For MAX8520: Analog FREQ Set Pin (see the Switching Frequency section).

FREQ

For MAX8521: Digital FREQ Selection Pin. Connect to VDD for 1MHz operation, connect to

GND for 500kHz operation. The PWM oscillator can synchronize to FREQ by switching at

FREQ between 700kHz and 1.2MHz.

D6, D5, D4

PGND2

Power Ground 2. Internal synchronous rectifier ground connection. Connect all PGND

pins together at the power ground plane.

E5, E6

LX2

Inductor Connection. LX2 is high-impedance in shutdown.

F5, F6

PVDD2

Power Input 2. Connect all PVDD inputs together at the VDD power plane.

Current-Sense Input. The current through the TEC is monitored between CS and OS1. The

maximum TEC current is given by 150mV/RSENSE and is bipolar.

OS2

Output Sense 2. OS2 senses one side of the differential TEC voltage. OS2 is a sense

point, not a power output. OS2 discharges to ground in shutdown.

OS1

Output Sense 1. OS1 senses one side of the differential TEC voltage. OS1 is a sense

point, not a power output. OS1 discharges to ground in shutdown.

F1, F2

PVDD1

Power Input 1. Connect all PVDD inputs together at the VDD power plane.

B2, B5, C3,

GND2

Ground. Additional ground pads aid in heat dissipation. Short to either GND or PGND

plane.

B3, B4

E3, E4

N.C.

No Connect. Connect N.C. pads to GND2 to aid in heat dissipation.

——

Exposed Paddle (TQFN Only). Internally connected to GND. Connect to a large ground

plane to maximize thermal performance. Not intended as an electrical connection point.

Pin Description (continued)

MAX8521 Datasheet(PDF) 9 Page - Maxim Integrated Products

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