LT3663EMS8E-5#PBF Linear Technology, LT3663EMS8E-5#PBF Datasheet - Page 7

• Manufacturer Part Number: LT3663EMS8E-5#PBF
• Description: IC BUCK 5V 1.2A 8MSOP
• Manufacturer: Linear Technology
• Type: Step-Down (Buck)r

Specifications of LT3663EMS8E-5#PBF

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 5V
• Current - Output: 1.2A
• Frequency - Switching: 1MHz
• Voltage - Input: 7.5 ~ 36 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP Exposed Pad, 8-HMSOP, 8-eMSOP
• Primary Input Voltage: 36V
• No. Of Outputs: 1
• Output Voltage: 5V
• Output Current: 1.2A
• No. Of Pins: 8
• Operating Temperature Range: -40°C To +125°C
• Msl: MSL 1 - Unlimited
• Switching Frequency Max: 1.65MHz
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -

OPERATION
The LT3663 is a constant frequency, current mode step
down regulator. A switch cycle is initiated when the os-
cillator enables the RS fl ip fl op, turning on the internal
power switch, Q1. The sense amplifi er (A1) monitors the
switch current via the voltage dropped across the current
sense resistor R
amplifi ed current signal with the output (V
amplifi er (G1). The switch is turned off when this current
exceeds a value determined by the V
amplifi er monitors the V
resistor divider and, when not driven externally, servos
the V
the V
current and V
on the V
internally compensated with a pole-zero combination on
the V
An external capacitor and internal diode, D2, generate a
voltage at the BOOST pin that is higher than the input supply.
C
C
C
voltage to regulate V
voltage will be driven higher increasing the output
node.
C
node provides current limit. The LT3663 is
OUT
SENSE1
voltage. An active clamp (not shown)
(Refer to Block Diagram)
. The comparator compares the
OUT
OUT
voltage through an internal
. If the V
C
OUT
voltage. The error
voltage drops,
C
) of the error
This allows the driver to fully saturate the internal bipolar
NPN power switch for effi cient operation. The switch driver
operates from either V
An internal regulator provides power to the control circuitry.
This regulator includes input undervoltage and overvoltage
protection which disables switching action when V
out of range. When switching is disabled, the LT3663
safely sustains input voltages up to 60V. Note that while
switching is disabled the output will discharge.
Output current limiting is provided via the servo action of
amplifi er G2. The voltage across sense resistor, R
is compared to a voltage programmed by external resistor
R
ripple current. If the average inductor current exceeds the
programmed value then the V
ing the current in the regulator. The output current limit
circuit allows for a lower current rated inductor and diode
and provides better control of system power dissipation.
ILIM
on the I
LIM
pin. A capacitor averages the inductor
IN
or BOOST to ensure startup.
C
voltage is pulled low, reduc-
LT3663
SENSE2
IN
3663fb
7
is
,