sx150x_89b-datasheet

ADVANCED COMMUNICATIONS & SENSING
Rev 4 – 26
th
April 2011 32 www.semtech.com
SX1508B/SX1509B
World’s Lowest Voltage Level Shifting GPIO
with LED Driver and Keypad Engine
6 A PPLICATION I NFORMATION
6.1 Typical Application Circuit
Figure 19 - Typical Application Schematic
6.2 Typical LED Connection
Typical LED Connection is described below. The LED is usually connected to a high voltage (VBAT) to take
advantage of the high sink current of the I/O and to accommodate high LED threshold voltages (VLED).
Please note that in this configuration the IO must be programmed as open drain output (RegOpenDrain) with no
pull-up (RegPullUp) and input buffer must be disabled (RegInputBufferDisable).
VCCx can take any value without compromising LED operation.
VCCx
IOx
VBAT
VCCx
VLED
*
*
LED colour/technology dependent
SX1508/9B
IOL
R
Figure 20 – Typical LED Operation
Serial R must be calculated for IOL not to exceed its max spec (Cf. Table 5) else VOL will increase.
VDDM
NRESET
SCL
SDA
ADDR1
GND
VCC1
I/O[0]
I/O[2]
I/O[3]
NINT
I/O[4]
I/O[5]
I/O[6]
I/O[7]
VCC2
SX1508B
SCL
SDA
I/O
I/O
3.3V
2.5V
1.2V
5V
Optional (depends
on the application)
5V
Host
controlle
r
OSCIO
I/O[1]
ADDR0