Tr i p ath Technol ogy, I n c. - Techni cal I n for m ati on

8

TLD4012 – JB/Rev. 2.0a/05.02

FUNCTIONAL DESCRIPTION

Programmable Gain

The gain of the TLD4012 is programmed by the digital inputs G3, G2, G1 and G0. The gain given below is

Characteristics).

Protection C i rcuits

The TLD4012 has built-in protection against over-temperature and over-current conditions. There are two

modes in which the fault protection circuits can operate depending on the state of the AUTO_CLR pin.

The two modes operate as follows:

1. AUTO_CLR pin is set to a logic low level - When the device goes into an over-temperature or over-

current condition, the FAULT pin is latched into a logic HIGH state indicating a fault condition. When

this occurs, the amplifier outputs enter disable mode and are in a high-impedance state provided

condition has been removed, a logic LOW pulse must be applied to the RESETB pin for a minimum of

100 ns to reset the FAULT output to a logic low level, and re-enable the output to a normal, low

impedance mode.

2. AUTO_CLR pin is set to a logic high level - After a fault occurs and the fault condition is removed, the

device will enable the outputs, and reset the FAULT pin every 1 micro-second. In this mode the fault

latch is reset internally on power up so an external reset is not required. Note that in the case of an

over-current fault, if the cause of the over-current condition has not actually cleared, the output stage

will cycle continuously between the normal, enabled state, and the fault, or disabled state. In this

mode the FAULT output pin can cycle continuously until the cause of the fault is cleared. If this

operation is not desirable, see the “Over-current Protection” section below. If a microcontroller or DMT

processor is used to monitor the FAULT output, and to control the device, AUTO_CLR should be set

to a logic low level. Otherwise, AUTO_CLR should be set to a logic high level and the device will reset

itself on power-up and after a fault condition has been removed.

G3 G2 G1 G0 Gain, dB Gain, V/V

0

0

0

0

12.8

4.37

0

0

0

1

13.8

4.90

0

0

1

0

14.8

5.50

0

0

1

1

15.8

6.17

0

1

0

0

16.8

6.92

0

1

0

1

17.8

7.76

0

1

1

0

18.8

8.71

0

1

1

1

19.8

9.77

1

0

0

0

20.8

10.96

1

0

0

1

21.8

12.30

1

0

1

0

22.8

13.80

1

0

1

1

23.8

15.49

1

1

0

0

24.8

17.38

1

1

0

1

25.8

19.50

1

1

1

0

26.8

21.88

1

1

1

1

27.8

24.55