sushant:
the chip i'm using is PCF8574 AP and the datasheet gives below value for the address:For PCF8574A the addressing is:
A2 A1 A0 Dec Hex
L L L 56 0x38
L L H 57 0x39
L H L 64 0x40
L H H 74 0x4A
H L L 75 0x4B
H L H 76 0x4C
H H L 77 0x4D
H H H 78 0x4E
The TI sheet I looked at didn't have the A version.
Are you using the NXP chip?
If so check the datasheet again, Page 9 specifically, and see that it tells you to include the LSB which you needed to do anyway and haven't, as you can see on pages 10 and 11.
Your address should be 0b01110000 = 0x70 = 112
Edit: i'm wrong. Wire adds the LSB