IR3621FPBF International Rectifier, IR3621FPBF Datasheet - Page 5

• Manufacturer Part Number: IR3621FPBF
• Description: 2-Phase Dual Synchronous PWM Controller with Oscillator Synchronization and Pre-Bias Startup
• Manufacturer: International Rectifier

Specifications of IR3621FPBF

• Package: 28-Pin TSSOP
• Circuit: Dual Sync PWM Controller or 2Phase Single Output
• Vcc (min): 4.7
• Vcc (max): 16
• Vout (min): 0.8
• Vout (max): Vcc * 0.90
• Switch Freq (khz): programmable to 500kHz
• Pbf: PbF Option Available

PIN DESCRIPTIONS
Note3: The negative voltage at these pins may cause instability for the gate drive circuits. To prevent this, a low
forward voltage drop diode (Schottky) is required between these pins and power ground.
TSSOP
10,18
12,16
13,15
11,17
5,23
6,22
7,21
9,19
20
14
24
25
26
27
28
1
2
3
4
8
9,15,25.32
MLPQ
10,14
11,13
2,22
3,21
4,20
6,18
7,17
8,16
29
30
31
19
12
23
24
26
27
28
1
5
PIN SYMBOL
OCSet2,OCSet1
Comp2, Comp1
PGnd2, PGnd1
HDrv2, HDrv1
VcH2, VcH1
LDrv2, LDrv1
V
SS2 / SD
SS1 / SD
SEN2
Fb2,Fb1
PGood
Hiccup
V
Sync
V
Gnd
Vcc
N/C
V
V
OUT3
Rt
REF
, V
P2
CL
SEN1
PIN DESCRIPTION
Power Good pin. Low when any of the outputs fall 10% below the set voltages.
Supply voltage for the internal blocks of the IC. The Vcc slew rate should be
<0.1V/us.
Output of the internal LDO. Connect a 1.0uF capacitor from this pin to ground.
Connecting a resistor from this pin to ground sets the oscillator frequency.
Sense pins for OVP and PGood. For current share tie these pins together.
Inverting inputs to the error amplifiers. In current sharing mode, Fb1 is con-
nected to a resistor divider to set the output voltage and Fb2 is connected to
programming resistor to achieve current sharing. In independent 2-channel mode,
these pins work as feedback inputs for each channel.
Compensation pins for the error amplifiers.
These pins provide user programmable soft-start function for each outputs.
Connect external capacitors from these pins to ground to set the start up time
for each output. These outputs can be shutdown independently by pulling the
respective pins below 0.3V. During shutdown both MOSFETs will be turned off.
For current share mode SS2 must be floating.
A resistor from these pins to switching point will set current limit threshold.
Supply voltage for the high side output drivers. These are connected to voltages
that must be typically 6V higher than their bus voltages. A 0.1µF high fre-
quency capacitor must be connected from these pins to PGND to provide peak
drive current capability.
Output drivers for the high side power MOSFETs. Note3
These pins serve as the separate grounds for MOSFET drivers and should be
connected to the system’s ground plane.
Output drivers for the synchronous power MOSFETs.
Supply voltage for the low side output drivers.
The internal oscillator can be synchronized to an external clock via this pin.
When pulled High, it puts the device current limit into a hiccup mode. When
pulled Low, the output latches off, after an overcurrent event.
Non-inverting input to the second error amplifier. In the current sharing mode, it
is connected to the programming resistor to achieve current sharing. In inde-
pendent 2-channel mode it is connected to V
the resistor divider to set the output voltage.
Reference Voltage. The drive capability of this pin is about 2 A.
Analog ground for internal reference and control circuitry.
No Connect
www.irf.com
REF
pin when Fb2 is connected to
IR3621 & (PbF)
5