Datasheet

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Pin Descriptions

5 Pin Descriptions

Table 1. Pin Descriptions

Pin # Name Description

A1 VIN Power Supply Input. Connect to input filter capacitor (see Typical Application Circuit).

Switching node. Connection to the internal NFET switch and PFET synchronous

A2 SW

rectifier.

A3 GND Ground Pin

B1 SDA I

C data (Use a 2kΩ pullup resistor.)

B2 PG Power Good indicator

B3 VOUT Output pin.

C1 SCLK I

C Clock (Use a 2KΩ pull up resistor.)

Enable pin. The device is in shutdown when voltage to this pin is < 0.4V and enabled

C2 EN

when > 1.2V. Do not leave this pin floating.

C3 BAL Balancing pin for active voltage balancing of super-capacitor.

6 Board Operation

To operate the LM8850, connections to VIN, Ground and the jumper on the enable pin must be in the H

position. To start out, supply 3.6V to VIN. With a valid supply, Vout should power up to 5V within 5

seconds.

Once enabled, the LM8850 charges the supercapacitor utilizing all of the default settings in the registers.

The I

C must be used to change the default settings and this can only be done with the LM8850 enabled.

Once a register is written to, the changes will transition immediately. Every time the EN pin transitions

from VIL to VIH, registers 0 and 1 are reset to their defaults settings and any settings needed bust

rewritten into the appropriate registers.

7 I

C-Compatible Chip Address

The device address for LM8850 is 60 (HEX).

CONTROL 00 R/W Control Register 0 (Figure 4)

CONTROL 01 R/W Control Register 1 (Figure 5)

SNVA472A–March 2011–Revised May 2013 AN-2119 LM8850 Evaluation Board Application Note

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