MAX603 Datasheet, PDF (8/12 Pages) Maxim Integrated Products – 5V/3.3V or Adjustable, Low-Dropout, Low IQ, 500mA Linear Regulators

5V/3.3V or Adjustable, Low-Dropout,
Low I_Q, 500mA Linear Regulators
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
1.0
0.2
1.3
POWER DISSIPATION vs.
GROUND PAD AREA
MAX603, V_OUT = 5V
8-PIN SO PACKAGE
PAPER EPOXY BOARD
SINGLE SIDED
1oz. COPPER
T_J = +125°C
T_A = +25°C STILL AIR
1
10
6.5
65
COPPER GROUND PAD AREA
20 (in²)
130 (cm²)
Figure 4. Typical Maximum Power Dissipation vs. Ground Pad
Size.
air, θ_JB (or θ_JC) is the thermal resistance of the package
chosen, and θ_BA is the thermal resistance through the
printed circuit board, copper traces and other materials
to the surrounding air. The 8-pin SOIC package for the
MAX603/MAX604 features a special lead frame with a
lower thermal resistance and higher allowable power
dissipation. The thermal resistance of this package is
θ_JB = 42°C/W, compared with θ_JB = 110°C/W for an 8-
pin plastic DIP package and θ_JB = 125°C/W for an 8-pin
ceramic DIP package.
The GND pins of the MAX603/MAX604 SOIC package
perform the dual function of providing an electrical con-
nection to ground and channeling heat away. Connect
all GND pins to ground using a large pad or ground
plane. Where this is impossible, place a copper plane
on an adjacent layer. The pad should exceed the
dimensions in Figure 4.
Figure 4 assumes the IC is an 8-pin SOIC package, is
soldered directly to the pad, has a +125°C maximum
junction temperature and a +25°C ambient air tempera-
ture, and has no other heat sources. Use larger pad
sizes for other packages, lower junction temperatures,
higher ambient temperatures, or conditions where the IC
is not soldered directly to the heat-sinking ground pad.
The MAX603/MAX604 can regulate currents up to
500mA and operate with input voltages up to 11.5V, but
not simultaneously. High output currents can only be
sustained when input-output differential voltages are
MAXIMUM OUTPUT CURRENT vs. SUPPLY VOLTAGE
MAX603
700
MAXIMUM CONTINUOUS CURRENT LIMIT
600
HIGH-POWER
SOIC
500
400
300
200
100
0
4
PLASTIC DIP
OPERATING
REGION AT
T_A = +25°C
T_J = +125°C
CERAMIC DIP
5 6 7 8 9 10 11 12 13
SUPPLY VOLTAGE (V)
MAX604
700
MAXIMUM CONTINUOUS CURRENT LIMIT
600
HIGH-POWER SOIC
500
400
300
200
100
0
2
PLASTIC DIP
OPERATING
REGION AT
T_A = +25°C
T_J = +125°C
CERAMIC DIP
3 4 5 6 7 8 9 10 11 12 13
SUPPLY VOLTAGE (V)
Figure 5. Power Operating Regions: Maximum Output Current
vs. Differential Supply Voltage
low, as shown in Figure 5. Maximum power dissipation
depends on packaging, board layout, temperature, and
air flow. The maximum output current is:
( ⁽ ) ^{) ( ) IOUT max}
=
P_MAX × T_J - T_A
V_IN - V_OUT × 100°C
where P_MAX is derived from Figure 4.
Reverse-Current Protection
The MAX603/MAX604 has a unique protection scheme
that limits reverse currents when the input voltage falls
below the output. It monitors the voltages on IN and
OUT and switches the IC’s substrate and power bus to
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