DAC2815SE 查看數據表（PDF） - M.S. Kennedy
零件编号
产品描述 (功能)
生产厂家
DAC2815SE Datasheet PDF : 6 Pages
| |||
TYPICAL PERFORMANCE
GRAPHS
DAC2812S • DAC2815S
OUTPUT ADJUST / COMP
The output voltage of the DAC2812S and DAC2815S may
be adjusted from 90% to 110% of nominal value by the use of
a 150KΩ potentiometer as shown. Adjustment beyond this
range is possible, however certain characteristics of the
converter such as but not limited to input voltage range,
efficiency, ripple and temperature performance will change.
Characterization by the user is recommended in such applica-
4
1
10nF
2
150K
tions.
Adjust/comp (pin 4) may be driven by external circuitry
referenced to pin 2 (-output) if desired. Grounding pin 4 causes
voltage to increase (25% typically) while driving pin 4 above
1.3 V causes output voltage to decrease. Pin 4 may be driven
negative without damage, however the resultant increase in
converter output voltage should be considered. Pin 4 may be
driven through 10KΩ or more if connection of the comp
function is also required.
The comp function of pin 4 allows load transient response to
be tailored to suit specific application requirements. This
feature may be utilized by connecting a 10 or less nF capacitor
between pins 4 and 1.
Note: The DAC2812S and DAC2815S use pin 4 while the
DHC2803S and DHC2805S use pin 3.
SHUTDOWN PLUS
Pin 5 is used for remote shutdown, output fault detection,
and/or setting the input voltage point at which the converter will
turn on as shown in the typical application diagram. No
connection to pin 5 is necessary for normal operation of the
converter. Pin 5 is referenced to pin 7 (-input).
Shutdown may be implemented by simply connecting pin 5
to an open collector logic output or switch rated at 2.5 mA, 25
Vdc or higher.
Input voltage turn on point is programmed with a single
resistor from pin 5 to 7. An input turn on/off hysteresis (typically
3.5% of Vin) will be observed. This should be considered when
making or verifying set point adjustment. The value of the
setpoint resistor may be determined by the following:
210 * 10 3
R=
ETO – 9.5
(+/– 10% accuracy at 25OC)
Set point temperature coefficient is typically + 400ppm/OC
Output fault monitoring is accomplished by observing pin 5
with a high impedance monitoring circuit. Pin 5 voltage drops
from over 10 V to below 1 V when a load fault causes the
converters fault protection circuitry to activate. It will remain
low for at least 100 mS and return high. If the load fault is still
present pin 5 will return low and the cycle will repeat. A resistor
> 400 KΩ from pin 5 to 7 provides pull down for pin 5 if there
is no input setpoint programming resistor already in place.
LOAD FAULT RESPONSE
The MSK families of DC-DC converters share load fault
philosophies. Load fault conditions include short-circuit and
severe overload conditions. The DAC2800 converter series
responds to load faults by turning off all power conversion
circuits for 250 mS and then attempting to restart for 10 mS
(typical). The net "on" duty factor during a fault is very low
resulting in low converter dissipation and immunity from over-
heating at 125°C. Current beyond rated can flow into the load
at startup time. This allows the converter to bring up capacitive
and other difficult load types more reliably than competing
converters.
Vo
O
Io
O
NORMAL
TIME
LOAD FAULT
NORMAL
5
Rev. A 3/01
Share Link: 