LM5069_10 NSC [National Semiconductor], LM5069_10 Datasheet - Page 3

• Manufacturer Part Number: LM5069_10
• Description: Output Voltage Clamping Using the LM5069 Hot Swap Controller
• Manufacturer: NSC [National Semiconductor]

Test Results
Two LM5069 circuits were tested with different value zener
diodes for Z1. In both tests the pertinent external components
were:
Transient testing was performed by quickly increasing V
from 10V to 20V for 20 milliseconds, and then returning V
to 10V. The scope photo in Figure 4 shows the results:
Trace 1: V
Trace 2: GATE pin (10/V/div)
Trace 3: TIMER pin (2V/div)
Trace 4: V
- R
- R
- Power Limit = 5 Watts
- Q1 = Vishay SUM40N15-38
S
PWR
= 20 mohms
OUT
IN
= 12.5 kohms
(10V/div)
(10V/div)
FIGURE 4. Transient Testing with Z1 = 20V
FIGURE 3. Z1 = 20V
IN
IN
3
A) In the first test, a 20V zener diode was used for Z1. The
circuit’s load resistance was 40 ohms, resistive. The result,
shown in Figure 3, is that the GATE pin was clamped at ap-
proximately 20V for V
clamped at between 15.6V and 17V as V
from 16V to 27V. In this test circuit, increasing V
activated the power limiting feature of the LM5069, and Q1
was shut off after the fault timeout period.
30119208
IN
>11V, and the output voltage was
30119209
IN
was increased
IN
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above 27V