EVM693AHJ Semtech Corporation, EVM693AHJ Datasheet - Page 5

• Manufacturer Part Number: EVM693AHJ
• Description: 500 MHz Monolithic Dual Pin Electronics Driver
• Manufacturer: Semtech Corporation

For system level flexibility, the SLEWADJ input is designed
to allow a voltage DAC, a current DAC, or a resistor to a
fixed voltage as possible slew rate control mechanisms
(see Figure 3).
Driver Bias
The BIAS pin is an analog current input that requires a
1.2 mA fixed reference current for the driver. Several
circuit configurations are usable to satisfy this
requirement, the most simple being a fixed resistor to a
fixed power supply, typically VCC (see Figure 4). Looking
into the BIAS node shows a .7 V voltage source with a
1.5 KW impedance, so the equation to select the fixed
resistor is:
Alternatively, a current DAC could be used to either
program the BIAS current or to perform subtle
adjustments in the fixed value.
EDGE HIGH-PERFORMANCE PRODUCTS
Circuit Description (continued)
2000 Semtech Corp.
Figure 4. Bias Current Generation
(VCC – .7) / (R + 1.5) = 1.2 mA
Figure 3. SLEWADJ Inputs
DVLCAP / DVHCAP
These two analog nodes are brought out to better
stabilize the high and low driver levels. Much like placing
decoupling capacitors on the DVL and DVH input pins,
the DVLCAP and DVHCAP pins require a fixed .01 F
chip capacitor (with good high frequency characteristics)
to ground (see Figure 5). A tight layout with minimum
etch is recommended.
Thermal Monitor
The Edge693 includes an on-chip thermal monitor
accessible through the THERMAL DIODE pin. This node
connects to 5 diodes in series to VEE (see Figure 6) and
may be used to accurately measure the junction
temperature at any time.
A bias current of 100 A is injected into this node, and
the measured voltage corresponds to a specific junction
temperature with the following equation:
T
J(˚C)
5
= {(V
THERMAL DIODE
Figure 5. DVLCAP and DVHCAP
Figure 6. Thermal Diode String
– VEE) / 5 – .7} / (–.00208).
Edge693
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