IR3624MTRPBF International Rectifier, IR3624MTRPBF Datasheet - Page 8

• Manufacturer Part Number: IR3624MTRPBF
• Description: IC CTRLR PWM SYNC BUCK 10-MLPD
• Manufacturer: International Rectifier

Specifications of IR3624MTRPBF

• Package / Case: 10-MLPD
• Voltage - Supply: 4.5 V ~ 14 V
• Frequency-max: 660kHz
• Operating Temperature: -40°C ~ 125°C
• Number Of Outputs: 1
• Duty Cycle: 71%
• Pwm Type: Voltage Mode
• Buck: Yes
• Boost: No
• Flyback: No
• Inverting: No
• Doubler: No
• Divider: No
• Cuk: No
• Isolated: No
• Frequency: 600kHz
• Supply Voltage Range: 4.5V To 14V
• Digital Ic Case Style: MLPD
• No. Of Pins: 10
• Operating Temperature Range: -40°C To +125°C
• Termination Type: SMD
• Input Voltage Primary Min: 5V
• Rohs Compliant: Yes
• Filter Terminals: SMD
• Control Mode: Voltage
• Controller Type: PWM
• Package: 10-Lead MLPD
• Circuit: Sync PWM Controller
• Vcc (min): 4.0
• Vcc (max): 14
• Vout (min): 0.6
• Vout (max): Vcc * 0.71
• Iout (a): 10
• Switch Freq (khz): Internal 600kHz
• Pbf: PbF Option Available
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: IR3624MPBFTR

THEORY OF OPEARTION
Introduction
The
synchronous controller and operates with a fixed
600kHz switching frequency, allowing the use of
small external components. The output voltage is
set by feedback pin (Fb) and the internal
reference voltage (0.6V). These are two inputs to
error amplifier. The error signal between these
two inputs is compared to a fixed frequency
linear sawtooth ramp and generates fixed
frequency pulses of variable duty-cycle (D) which
drivers N-channel external MOSFETs.
The timing of the IC is controlled by an internal
oscillator circuit that uses on-chip capacitor to set
the switching frequency.
The IR3624 operates with single input voltage
from 4.5V to 12V allowing an extended operating
input voltage range.
The current limit is programmable and uses on-
resistance of the low-side MOSFET, eliminating
the need for external current sense resistor
Under-Voltage Lockout
The under-voltage lockout circuit monitors the
two input supplies (Vcc and Vc) and assures that
the MOSFET driver outputs remain in the off
state whenever the supply voltage drops below
set thresholds. Lockout occurs if Vc or Vcc fall
below 3.3V and 4.2V respectively. Normal
operation resumes once Vc and Vcc rise above
the set values.
Thermal Shutdown
Temperature sensing is provided inside IR3624.
The trip threshold is typically set to 145
trip threshold is exceeded, thermal shutdown
turns off both MOSFETs. Thermal shutdown is
not latched and automatic restart is initiated
when the sensed temperature drops within the
operating range. There is a 20
the thermal shutdown threshold.
Circuit Description
IR3624
is
a
voltage
o
C hysteresis in
mode
o
C. When
.
PWM
(Output Voltage before startup)
Pre-Bias Voltage
Shutdown
The output can be shutdown by pulling the soft-
start pin below 0.3V. This can be easily done by
using an external small signal transistor. During
shutdown both MOSFET drivers will be turned
off. Normal operation will resume by cycling soft
start pin.
Error Amplifier
The IR3624 is a voltage mode controller. The
error amplifier is of transconductance type. The
amplifier is capable of operating with Type III
compensation control scheme using low ESR
output capacitance.
Pre-Bias Startup
IR3624 is able to start up into pre-charged
output,
disturbances of the output voltage.
The output starts in asynchronous fashion and
keeps the synchronous MOSFET off until the first
gate signal for control MOSFET is generated.
Figure 4 shows a typical Pre-Bias condition at
start up.
Depends
amount of output capacitors may be required to
prevent discharging the output voltage.
Volt
which
on system
Fig. 4: Pre-Bias start up
prevents
IR3624MPBF
configuration, specific
oscillation
Time
Vo
and
8