iru3038 International Rectifier Corp., iru3038 Datasheet - Page 3

• Manufacturer Part Number: iru3038
• Description: Synchronous Pwm Controller For Termination Power Supply Applications
• Manufacturer: International Rectifier Corp.

PARAMETER
Error Amp
Fb Voltage Input Bias Current
Fb Voltage Input Bias Current
V
Transconductance
Oscillator
Frequency
Ramp Amplitude
Output Drivers
Rise Time
Fall Time
Dead Band Time
Max Duty Cycle
Min Duty Cycle
PIN DESCRIPTIONS
PIN#
Rev. 2.0
09/12/02
P
14
10
12
13
11
1
2
3
4
5
6
7
8
9
Voltage Range
PIN SYMBOL
Comp
PGnd
HDrv
V
LDrv
Gnd
Vcc
NC
SS
Vc
Fb
V
Rt
REF
P
This pin is connected directly to the output of the switching regulator via resistor divider to
provide feedback to the Error amplifier.
Non-inverting input of error amplifier.
Reference Voltage.
This pin provides biasing for the internal blocks of the IC as well as power for the low side
driver. A minimum of 1mF, high frequency capacitor must be connected from this pin to
ground to provide peak drive current capability.
No Connection.
Output driver for the synchronous power MOSFET.
Analog ground for internal reference and control circuitry. Connect to PGnd with a short
trace.
This pin serves as the separate ground for MOSFET's drivers and should be connected to
system's ground plane. A high frequency capacitor (0.1 to 1mF) must be connected from
Vcc and Vc pins to this pin for noise free operation.
Output driver for the high side power MOSFET. Connect a diode, such as BAT54 or 1N4148,
from this pin to ground for the application when the inductor current goes negative (Source/
Sink), soft-start at no load and for the fast load transient from full load to no load.
This pin is connected to a voltage that must be at least 4V higher than the bus voltage of
the switcher (assuming 5V threshold MOSFET) and powers the high side output driver. A
minimum of 1mF, high frequency capacitor must be connected from this pin to ground to
provide peak drive current capability.
The switching frequency can be Programmed between 200KHz and 400KHz by connect-
ing a resistor between Rt and Gnd. Floating the pin set the switching frequency to 200KHz
and grounding the pin set the switching frequency to 400KHz.
Compensation pin of the error amplifier. An external resistor and capacitor network is
typically connected from this pin to ground to provide loop compensation.
This pin provides soft-start for the switching regulator. An internal current source charges
an external capacitor that is connected from this pin to ground which ramps up the output
of the switching regulator, preventing it from overshooting as well as limiting the input
current. The converter can be shutdown by pulling this pin below 0.5V.
PIN DESCRIPTION
V
SYM
Freq
T
T
T
I
I
g
RAMP
FB1
FB2
OFF
T
T
ON
DB
m
r
f
SS=3V, Fb=1V
SS=0V, Fb=1V
Rt=Open
Rt=Gnd
C
C
Fb=1V, Freq=200KHz
Fb=1.5V
LOAD
LOAD
=1500pF
=1500pF
TEST CONDITION
www.irf.com
1.225
MIN
450
180
360
0.8
50
85
0
TYP
1.25
-0.1
600
200
400
150
-64
50
50
90
0
1.275
MAX
750
220
440
100
100
250
1.5
95
IRU3038
UNITS
mmho
KHz
mA
mA
ns
ns
ns
%
%
V
V
3