Rainbow Electronics LM63 - Manual (Page 2)

Pin Descriptions
Pin Name Input/Output Function and Connection
1 V
DD
Power Supply Input
Connect to a low-noise +3.3 ± 0.3 VDC power supply, and bypass to GND
with a 0.1 µF ceramic capacitor in parallel with a 100 pF ceramic capacitor.
A bulk capacitance of 10 µF needs to be in the vicinity of the LM63’s V
DD
pin.
2 D+ Analog Input
Connect to the anode (positive side) of the remote diode. A 2.2 nF ceramic
capacitor must be connected between pins 2 and 3.
3 D− Analog Input
Connect to the cathode (negative side) of the remote diode. A 2.2 nF
ceramic capacitor must be connected between pins 2 and 3.
4 PWM
Open-Drain
Digital Output
Open-Drain Digital Output. Connect to fan drive circuitry. The power-on
default for this pin is low (pin 4 pulled to ground).
5 GND Ground This is the analog and digital ground return.
6 ALERT/TACH Digital I/O
Depending on how the LM63 is programmed, this pin is either an
open-drain ALERT output or a tachometer input for measuring fan speed.
The power-on default for this pin is the ALERT function.
7 SMBDAT
Digital Input/
Open-Drain Output
This is the bi-directional SMBus data line.
8 SMBCLK Digital Input Digital Input. This is the SMBus clock input.
Simplified Block Diagram
20057002
LM63
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