Data Sheet No. PD94122
IRU1015
1.5A LOW DROPOUT POSITIVE
ADJUSTABLE REGULATOR
FEATURES
Guaranteed < 1.3V Dropout at Full Load Current
Fast Transient Response
1% Voltage Reference Initial Accuracy
Output Current Limiting
Built-In Thermal Shutdown
APPLICATIONS
486DX4 Supply Voltage
P55 I/O Supply Voltage
VGA & Sound Card Applications
Low Voltage High Speed Termination Applications
Standard 3.3V Chip Set and Logic Applications
TYPICAL APPLICATION
5V
C1
1500uF
Vin
3
DESCRIPTION
The IRU1015 is a low dropout three-terminal adjustable
regulator with minimum of 1.5A output current capability. This product is specifically designed to provide well
regulated supply for low voltage IC applications such as
486DX4 processor, P55C I/O supply as well as high
speed bus termination and low current 3.3V logic supply. The IRU1015 is also well suited for other applications such as VGA and sound card. The IRU1015 is
guaranteed to have <1.3V dropout at full load current
making it ideal to provide well regulated outputs of 2.5V
to 3.3V with 4.75V to 7V input supply.
1015app1-1.1
Figure 1 - Typical application of IRU1015 in a 5V to 3.3V regulator
Note: P55C is trademark of Intel Corp.
IRU1015
Vout
Adj
2
R1
121
1
R2
200
3.3V / 1.5A
C2
1500uF
PACKAGE ORDER INFORMATION
Tj (°C) 3-PIN PLASTIC 3-PIN PLASTIC 2-PIN PLASTIC
TO-220 (T) TO-263 (M) TO-252 (D-Pak)
0 To 150 IRU1015CT IRU1015CM IRU1015CD
Rev. 1.1
06/29/01
1
IRU1015
ABSOLUTE MAXIMUM RATINGS
Input Voltage (Vin) .................................................... 7V
Power Dissipation ..................................................... Internally Limited
Storage Temperature Range ...................................... -65°C To 150°C
Operating Junction Temperature Range ..................... 0°C To 150°C
PACKAGE INFORMATION
3-PIN PLASTIC TO-220 (T) 3-PIN PLASTIC TO-263 (M) 2-PIN PLASTIC TO-252 (D-Pak)
Tab is
Vout
FRONT VIEW
FRONT VIEW
3
2
1
Vin
Vout
Adj
Tab is
Vout
3
Vin
Vout
1
Adj
Tab is
Vout
FRONT VIEW
3
Vin
1
Adj
θJT=2.7°C/W θJA=60°C/W θJA=35°C/W for 1" Square pad θJA=70°C/W for 0.5" Square pad
ELECTRICAL SPECIFICATIONS
Unless otherwise specified, these specifications apply over Cin=1µF, Cout=10µF, and Tj=0 to 150!C.
Typical values refer to Tj=25!C.
PARAMETER SYM TEST CONDITION MIN TYP MAX UNITS
Reference Voltage Vref Io=10mA, Tj=25!C, (Vin-Vo)=1.5V 1.238 1.250 1.262 V
Io=10mA, (Vin-Vo)=1.5V 1.225 1.250 1.275
Line Regulation Io=10mA, 1.3V<(Vin-Vo)<7V 0.2 %
Load Regulation (Note 1) Vin=3.3V, Vadj=0, 10mA<Io<1.5A 0.4 %
Dropout Voltage (Note 2) ∆Vo Note 2, Io=1.5A 1.1 1.3 V
Current Limit Vin=3.3V, dVo=100mV 1.6 A
Minimum Load Current Vin=3.3V, Vadj=0V 5 10 mA
(Note 3)
Thermal Regulation 30ms Pulse, Vin-Vo=3V, Io=1.5A 0.01 0.02 %/W
Ripple Rejection f=120Hz, Co=25µF Tantalum,
Io=0.75A, Vin-Vo=3V 60 70 dB
Adjust Pin Current Iadj Io=10mA, Vin-Vo=1.5V, Tj=25!C,
Io=10mA, Vin-Vo=1.5V 55 120 µA
Adjust Pin Current Change Io=10mA, Vin-Vo=1.5V, Tj=25!C 0.2 5 µA
Temperature Stability Vin=3.3V, Vadj=0V, Io=10mA 0.5 %
Long Term Stability Tj=125!C, 1000Hrs 0.3 1 %
RMS Output Noise Tj=25!C, 10Hz<f<10KHz 0.003 %Vo
Note 1: Low duty cycle pulse testing with Kelvin connections is required in order to maintain accurate data.
Note 2: Dropout voltage is defined as the minimum differential voltage between Vin and Vout required to maintain regulation at Vout. It is measured when the output
voltage drops 1% below its nominal value.
2
Note 3: Minimum load current is defined as the mini-
mum current required at the output in order for the output voltage to maintain regulation. Typically the resistor
dividers are selected such that it automatically main-
tains this current.
Rev. 1.1
06/29/01
PIN DESCRIPTIONS
PIN # PIN SYMBOL PIN DESCRIPTION
1
Adj
A resistor divider from this pin to the Vout pin and ground sets the output voltage.
IRU1015
2
3
Vout
Vin
The output of the regulator. A minimum of 10µF 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 Vout
in order for the device to regulate properly.
BLOCK DIAGRAM
Vin 3
CURRENT
LIMIT
2 Vout
+
1.25V
+
THERMAL
SHUTDOWN
Figure 2 - Simplified block diagram of the IRU1015
APPLICATION INFORMATION
Introduction
The IRU1015 adjustable Low Dropout (LDO) regulator is
a three-terminal device which can easily be programmed
with the addition of two external resistors to any voltages within the range of 1.25 to 5.5 V.This regulator unlike 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 differential to maintain output regulation. This is a key requirement for today’s microprocessors that need typically
3.3V supply and are often generated from the 5V supply. Another major requirement of these microproces-
1015blk1-1.0
sors is the need to switch the load current from zero to
full load in tens of nanoseconds at their pins, which
translates to an approximately 300 to 500ns current step
at the regulator. In addition, the output voltage tolerances are sometimes tight and they include the transient response as part of the specification.
The IRU1015 is specifically designed to meet the fast
current transient needs as well as provide an accurate
initial voltage, reducing the overall system cost with the
need for fewer output capacitors.
1 Adj
Rev. 1.1
06/29/01
3