8

LTC1623

Address

The LTC1623 has an address of 1011XXX; the four MSBs

are hard-wired, but the 3 LSBs are programmed by the

user with the help of two three-state address pins. Refer to

Table 1 for the pin configurations and their corresponding

addresses.

To conserve standby current, it is preferable to tie the

addresses are needed, then either one of the address pins

value resistors (

≤1M) shown in Figure 2. Do not connect

because this is not a valid address.

Charge Pump

To fully enhance the external N-channel switches, an

internal charge pump is used to boost the output gate drive

output voltage limit is to avoid switch gate source break-

down due to excessive gate overdrive. A feedback network

Because the output will only need to drive the gate of the

external switch by charging and discharging the parasitic

gate capacitances, the internal charge pump, clocked by

an approximately 300KHz oscillator, is appropriately sized

to source less than 100

µA.

Power-On Reset and Undervoltage Lockout

The LTC1623 starts up with both gate drives low. An

internal power-on reset (POR) signal inhibits operation

until about 300

lockout threshold (typically 2V). The circuit includes some

hysteresis and delay to avoid nuisance resets. Once opera-

100

µs to trigger another POR sequence.

During standby, when both gate drive outputs are dis-

abled, quiescent current is kept to a minimum (13

µA

typical) because only the UVLO block is active.

Input Threshold

Anticipating the trend toward lower supply voltages, the

While some SMBus parts may violate this stringent SMBus

spondingly higher input supply voltage, the LTC1623

meets and maintains the constant SMBus input threshold

specification across the entire supply voltage range of

2.7V to 5.5V.

Figure 2. LTC1623 Programmed with Address 1011001

1

2

3

4

8

7

6

5

GA

GB

AD1

DATA

CLK

AD0

GND

DATA

CLOCK

LTC1623

LOAD1

1M

1M

LOAD2

1623 F02

Table 1. Address Pin Truth Table

AD0

AD1

ADDRESS

GND

GND

1011000

GND

1011001

GND

1011010

GND

1011011

UNUSED

1011100

GND

1011101

1011110

1011111

OPERATIO