DTL2A-LC データシートの表示（PDF） - Murata Manufacturing
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DTL2A-LC Datasheet PDF : 5 Pages
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DTL Series
DTL2A-LC Model
100 Watt, Digitally Programmable
Low-Voltage, Electronic Loads
Initialization
Preparing the DTL2A-LC to accept new digital data is accomplished by applying
logic "1's" to Control Strobe (CS, pin 7), Latch Data (LD, pin 4) and Clock
(CLK, pin 6) with all signals present and stable for a minimum of 1μsec.
During this interval, it does not matter whether or not data is present on the
Serial Data In (SDI, pin 5) line.
Serial Data
Following initialization, the 12-bit digital word representing the desired output
current is applied to the SDI pin. The serial data should appear starting with
the most significant bit (MSB, bit 1, D11) and ending with the least significant
bit (LSB, bit 12, D0). With each data bit present and stable on the SDI line,
the CLK must be toggled through a low-to-high transition to register that bit.
Twelve rising clock edges, at rates up to 500kHz, are required to clock all 12
digital bits into the DTL2A-LC’s input register.
Latching Data and Presenting It to the D/A
After loading the LSB, the serial data word is latched by bringing the Control
Strobe (pin 7) high and then toggling the Latch Data pin (pin 4) through a
high-low-high sequence. Approximately 100μsec later, the output current will
settle to its final desired value.
Software: C Language
The following steps describe a typical timing sequence when using the DTL2A-
LC’s 4 digital inputs and a programming language such as C. Using 4 bits of
a typical 8-bit port, assign BIT_0 to the Control Strobe (CS, pin 7), BIT_1 to
Latch Data (LD, pin 4), BIT_2 to Serial Data In (SDI, pin 5), and BIT_3 to
the Clock (CLK, pin 6).
1. Initialize with Control Strobe, Latch Data, and Clock high:
BIT_0 = 1, BIT_1 = 1, BIT_2 = X (don’t care), BIT_3 = 1
2. Bring the Control Strobe low.
BIT_0 = 0
3. Apply the MSB (D11) of the serial data word to Serial Data In.
BIT_2 = 0 or 1
4. Toggle the Clock high-low-high.
BIT_3 = 1 to 0 to 1
5. Apply D10 of the serial data word to Serial Data In.
BIT_2 = 0 or 1
6. Toggle the Clock high-low-high.
BIT_3 = 1 to 0 to 1
7. Repeat the process for remaining data bits D9 through D0.
8. Drive the Control Strobe high.
BIT_0 = 1
9. Toggle the Latch Data input high-low-high.
BIT_1 = 1 to 0 to 1.
Output Compliance Voltage and the Fault Line
For proper operation, the DTL2A-LC’s output/load voltage must always be
between 0.6 and 50 Volts. The device cannot be used to directly load
extremely low-voltage (<0.6V) power components or to simulate a true short
circuit (0 Volts). Voltages greater than 50V can damage the device. Voltages
<0.6V will result in insufficient biasing of the output current source and
consequently unpredictable or no operation. Accordingly, we have installed
an internal output/load-voltage monitoring circuit. If the output/load voltage
drops below 0.6V and the DTL2A-LC’s output is at risk of becoming disabled,
the Fault line activates.
The Fault line is an optically isolated, active-low function with an open-
collector output (internal 10kΩ pull-up resistor to +5V). Under normal condi-
tions, its output is high (logic "1"). Under fault conditions (VOUT < 2.5V), its
output drops to a logic "0." There is no output/load-voltage monitoring circuit
for voltages greater than 50V, and operation above 50V can damage the
device.
An "offset supply" can be inserted between the DTL2A-LC’s –Load output
(pins 8 and 9) and the power device under test (DUT) to "translate" the
DTL2A-LC’s 49.4V output/load voltage range. The offset supply must have
adequate current capabilities and be connected with the polarities indicated
in Figure 2 below. Under no circumstances should the voltage across the
DTL2A-LC’s output be allowed to experience a polarity reversal.
If a 5V/20A offset supply is inserted as shown, the range of DUT voltages will
be –4.4 to +45 Volts. Such a configuration can be used for true short-circuit
testing. A mechanical relay can be used to short the outputs of the DUT
while the offset supply ensures the DTL2A-LC always sees at least 5 Volts
across its outputs.
11
+LOAD
10
DTL2A-LC
9
–LOAD
8
5V
–
+
+
DUT
–
SHORT
CIRCUIT
RELAY
Figure 2. An "Offset Supply" Enables
True Short-Circuit Testing
Thermal Considerations
The DTL2A-LC can reliably handle 100W loads if its case temperature is
maintained at or below +50°C. With no heat sinking or auxiliary cooling, the
device can only handle loads up to 10 Watts. Please refer to the Temperature
Derating Curve for additional information. DATEL’s Electronic Load Applica-
tions Engineers can assist you in developing heat-sink solutions for your
higher-power DTL2A-LC applications. Please contact us for details.
www.murata-ps.com
Technical enquiries email: sales@murata-ps.com, tel: +1 508 339 3000
MDC_DTL2A-LC Page 4 of 5
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