| Parameter | Sym | Conditions | Min | Typ | Max | Unit |
| TONE output pin DC level | Vdc | V-- = 2.OV~5.5V DD | 0.5V-- | | 0.7VDD | v |
| sink current | Itl | Vdtmf= 0.5V | 0.2 | | | mA |
| AC level | Vdtmf | Row group, RL = 10KI | 130 | 155 | 170 | mVrmS |
| Load resistor | Rl | Dist." -23dB | 10 | | | Kl |
| DTMF signal: pre-emphasis | twist | VDD = 2.0~5.5V, Column-Row group | 1 | 2 | 3 | dB |
| *distortion | Dist. | RL=10KI | | -30 | -23 | dB |
| Minimum tone duration | tTD | Auto redial | | 98/83 | | ms |
| Minimum intertone pause | tITP | Auto redial | | 98/83 | | ms |
| | | | | | |
An important detail to remember is that at low input supply voltages, the RDS(ON) of the P-channel switch increases (see Typical Performance Characteristics). Therefore, the user should calculate the power dissipa- tion when the LTC3408 is used at 100% duty cycle with low input voltage (See Thermal Considerations in the Applications Information section).