E7765AXF Semtech, E7765AXF Datasheet - Page 7

• Manufacturer Part Number: E7765AXF
• Manufacturer: Semtech

Specifications of E7765AXF

• Lead Free Status / Rohs Status: Not Compliant

Driver Slew Rate Adjustment
The driver rising and falling transition times are indepen-
dently adjustable. The RADJ and FADJ pins are analog
current inputs which establish the driver rise and fall times.
Ideally, an adjustable external current source would be
used for RADJ and FADJ. However, for applications where
the rise and fall times are fixed, precision external resis-
tors to a positive voltage can be used. The currents into
RADJ and FADJ follow the equation:
The diagrams opposite show how driver rise and fall are
adjusted by RADJ, FADJ and DBIAS.
Power Down of the Driver
Referring to Table 1, there are configurations in which a
driver can be put into a power down mode, and others in
which the driver is powered and ready for operation.
PON[0:3] are the TTL inputs controlling power to the indi-
vidual driver circuits. A logical 1 will power up the driver.
The PON inputs remain effective on a per-driver basis in
differential mode.
©
TEST AND MEASUREMENT PRODUCTS
Circuit Description (continued)
2006 Semtech Corp. , Rev. 11, 7/18/06
RADJ, FADJ = (VCC - 0.7) / (Rext + 550 ).
RADJ, FADJ
VEE
550Ω
Rise/Fall
Adjust Current
Rext
VCC
Thermal Monitor
An on-chip thermal diode string of five diodes in series
exists (see figure below). This string allows accurate die
temperature measurements.
An external bias current of 100 µA is injected through the
string, and the measured voltage corresponds to a spe-
cific junction temperature with the following equation:
Tj[°C] = {(ANODE – CATHODE) / 5 – 0.768} / (–0.00169).
Power Supply Sequencing
In order to avoid the possibility of latch-up, the following
power-up requirements must be satisfied:
The following sequencing can be used as a guideline when
powering up the E7765:
The recommended power-down sequence is the reverse
order of the power-up sequence.
7
1.
2.
3.
1.
2.
3.
4.
VEE <= GND <= VCC at all times
VEE <= Analog Inputs <= VCC
VEE <= Digital Inputs <= input max voltage or
VEE
VCC
Digital Inputs
Analog Inputs
VCC, whichever is less
CATHODE
ANODE
Temperature Coefficient =
Bias Current
-7.9 mV / °C
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E7765