NT91315XL Series
Pin Descriptions (continued)
Pin No.
Designation I/O
Description
NT91315AL NT91315BL NT91315CL NT91315DL
(N.A.)
(N.A.)
10
10
HDO
O HOLD output pin
This inverter output pin will stay high when
HOLD function is active
(N.A.)
(N.A.)
11
13
HDI
I The HOLD function will be toggled when this
pin goes from high to low in the OFF HOOK
state
(N.A.)
(N.A)
(N.A.)
12
1
1
1
(N.A.)
18
20
22
KT
HFO
HFI
O Key-in tone output
This N-channel open drain pin sends out a
"beep" tone for each PULSE mode and each
store state key entry, as well as for entries of
accepted function keys (ST, F, A/L, R/P,
SAVE and memory keys). Tone output
frequency is 437 Hz and tone duration is 27
ms
O Hands-Free Control I/O pins These pins
enable and disable the Hands-Free Control
function. When input pin HFI goes low, the
Hands-Free Control state is toggled on. The
status of the Hands-Free Control state is
listed in the following table:
Current
State
Next States
Hook HFO Input HFO Dialing?
sw.
-
Low HFI ↓ High
Yes
I
On High HFI ↓ Low
No
Hook
Off High HFI ↓ Low Yes
Hook
On
- Off Low Yes
Hook
Hook
Off Low On Low No
Hook
Hook
Off High On High Yes
Hook
Hook
9