X-11181-002 Datasheet(PDF) 6 Page - Linear Technology
LINER [Linear Technology]
CTRL1, CTRL2, CTRL3 (Pin 1, Pin 2, Pin 3): Current
Output Adjustment Pins. These pins control the output
current. The lowest value out of the three CTRL inputs is
compared to negative input of the operational amplifier.
(Pin 4): Voltage Reference Output Pin. Typically 2V.
This pin drives a resistor divider for the CTRL pin, either
for analog dimming or for temperature limit/compensation
of output load. Can supply up to 200Î¼A.
OVP (Pin 5): Overvoltage Protection. This pin accepts a
DC voltage to compare to the sample and holdâ€™s voltage
output information. When output voltage information is
above the OVP, the part divides the minimum switching
frequency by 8, around 500Hz. This protects devices con-
nected to the output. This also allows the part to operate
with very little power consumption with no load to meet
energy star requirements.
VC (Pin 6): Compensation Pin for Internal Error Amplifier.
Connect a series RC from this pin to ground to compensate
the switching regulator. A 100pF capacitor in parallel helps
(Pin 7, Pin 8): Compensation Pins for
Internal Error Amplifier. Connect a capacitor between these
two pins to compensate the internal feedback loop.
FB (Pin 9): Voltage Loop Feedback Pin. FB is used to
regulate the output voltage by sampling the third wind-
ing. If the converter is used in current mode, the FB pin
will normally be at a voltage level lower than 1.25V, and
will reach the steady state of 1.25V if it detects an open
DCM (Pin 10): Discontinuous Conduction Mode Detection
Pin. Connect a capacitor and resistor in series with this
pin to the third winding.
(Pin 11): Input Voltage. This pin supplies current to
the internal start-up circuitry and to the INTV
pin must be locally bypassed with a capacitor. A 42V shunt
regulator is internally connected to this pin.
EN/UVLO (Pin 12): Enable/Undervoltage Lockout. A resis-
tor divider connected to V
is tied to this pin to program
the minimum input voltage at which the LT3798 will turn
on. When below 1.25V, the part will draw 60Î¼A with most
of the internal circuitry disabled and a 10Î¼A hysteresis
current will be pulled out of the EN/UVLO pin. When above
1.25V, the part will be enabled and begin to switch and the
10Î¼A hysteresis current is turned off.
(Pin 13): Regulated Supply for Internal Loads
and GATE Driver. Supplied from V
and regulates to 10V
must be bypassed with a 4.7Î¼F capacitor
placed close to the pin.
Power Factor vs Input Voltage
Efficiency vs Input Voltage
PAGE 17 SCHEMATIC:
PAGE 17 SCHEMATIC:
TYPICAL PERFORMANCE CHARACTERISTICS
= 25Â°C, unless otherwise noted.
Does ALLDATASHEET help your business so far?
[ DONATE ]
All Rights ReservedÂ©
2003 - 2017
|   Chinese :
| German :
| Japanese :
| Russian :
| Spanish :
| French :
| Italian :
| Portuguese :
| Polish :