iru1030 International Rectifier Corp., iru1030 Datasheet - Page 3

• Manufacturer Part Number: iru1030
• Description: 3a Low Dropout Positive Adjustable Regulator
• Manufacturer: International Rectifier Corp.

PIN DESCRIPTIONS
PIN #
BLOCK DIAGRAM
APPLICATION INFORMATION
Introduction
The IRU1030 adjustable Low Dropout (LDO) regulator is
a three-terminal device which can easily be programmed
with the addition of two external resistors to any volt-
ages within the range of 1.25 to 5.5V. This regulator un-
like the first generation of the three-terminal regulators
such as LM117 that required 3V differential between the
input and the regulated output, only needs 1.3V differen-
tial to maintain output regulation. This is a key require-
ment for today’s microprocessors that need typically
3.3V supply and are often generated from the 5V sup-
ply. Another major requirement of these microproces-
sors such as the Intel P54C
load current from zero to several amps in tens of nano-
Rev. 1.3
08/20/02
1
2
3
V
IN
PIN SYMBOL
3
V
Adj
V
OUT
IN
SHUTDOWN
THERMAL
CURRENT
LIMIT
A resistor divider from V
The output of the regulator. A minimum of 10 F capacitor must be connected from this pin
to ground to insure stability.
The input pin of the regulator. Typically a large storage capacitor is connected from this
pin to ground to insure that the input voltage does not sag below the minimum drop out
voltage during the load transient response. This pin must always be 1.3V higher than V
in order for the device to regulate properly.
PIN DESCRIPTION
is the need to switch the
Figure 2 - Simplified block diagram of the IRU1030.
+
OUT
www.irf.com
to Adj pin to ground sets the output voltage.
seconds at the processor pins, which translates to an
approximately 300 to 500ns current step at the regula-
tor. In addition, the output voltage tolerances are also
extremely tight and they include the transient response
as part of the specification. For example Intel VRE
specification calls for a total of 100mV including initial
tolerance, load regulation and 0 to 4.6A load step.
The IRU1030 is specifically designed to meet the fast
current transient needs as well as providing an accurate
initial voltage, reducing the overall system cost with the
need for fewer output capacitors.
1.25V
+
IRU1030
2 V
1 Adj
OUT
OUT
3