THS6002 Datasheet, PDF (25/40 Pages) Texas Instruments – DUAL DIFFERENTIAL LINE DRIVERS AND RECEIVERS

THS6002
DUAL DIFFERENTIAL LINE DRIVERS AND RECEIVERS
SLOS202D– JANUARY 1998– REVISED JULY 1999
APPLICATION INFORMATION
power supply restrictions
Although the THS6002 is specified for operation from power supplies of ± 5 V to ±15 V (or singled-ended power
supply operation from 10 V to 30 V), and each amplifier has its own power supply pins, several precautions must
be taken to assure proper operation.
1. The power supplies for each amplifier must be the same value. For example, if the drivers use ±15 volts,
then the receivers must also use ±15 volts. Using ±15 volts for one amplifier and ±5 volts for another
amplifier is not allowed.
2. To save power by powering down some of the amplifiers in the package, the following rules must be
followed.
• The amplifier designated Receiver 1 must always receive power whenever any other amplifier(s) within
the package is used. This is because the internal startup circuitry uses the power from the Receiver 1
device.
• The –V_CC pins from all four devices must always be at the same potential.
• Individual amplifiers are powered down by simply opening the +V_CC connection.
As an example, if only the two drivers within the THS6002 are used, then the package power is reduced by
removing the +V_CC connection to Receiver 2. This reduces the power consumption by an amount equal to the
quiescent power of a single receiver amplifier. The +V_CC connections to Receiver 1 and both drivers are
required. Also, all four amplifiers must be connected to –V_CC, including Receiver 2.
The THS6002 incorporates a standard Class A-B output stage. This means that some of the quiescent current
is directed to the load as the load current increases. So under heavy load conditions, accurate power dissipation
ǒ Ǔ ₎ ǒ Ǔ _{ǒ Ǔ} ^{calculations are best achieved through actual measurements. For small loads, however, internal power}
dissipation for each amplifier in the THS6002 can be approximated by the following formula:
PD ≅ 2 VCC ICC VCC _ VO
VO
RL
Where:
P_D = power dissipation for one amplifier
V_CC = split supply voltage
I_CC = supply current for that particular amplifier
V_O = output voltage of amplifier
R_L = load resistance
To find the total THS6002 power dissipation, we simply sum up all four amplifier power dissipation results.
Generally, the worst case power dissipation occurs when the output voltage is one-half the V_CC voltage. One
last note, which is often overlooked: the feedback resistor (R_F) is also a load to the output of the amplifier and
should be taken into account for low value feedback resistors.
• POST OFFICE BOX 655303 DALLAS, TEXAS 75265
25