5A/2A Step-Down, PWM,
Switch-Mode DC-DC Regulators
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 25V, T
j
= T
MIN
to T
MAX
, unless otherwise noted.)
PARAMETER
Error-Amplifier Voltage Gain
Error-Amplifier Transconductance
Error-Amplifier Source Current
Error-Amplifier Sink Current
Feedback Pin Bias Current
Reference Voltage
Reference Voltage Tolerance
Reference Voltage Line Regulation
VC Voltage at 0% Duty Cycle
Thermal Resistance,
Junction to Case (Note 6)
MAX724
MAX726
V
FB
= 2V
V
FB
= 2.5V
V
FB
= VREF
V
C
= 2V
VREF (nominal) = 2.21V
T
j
= +25°C
All conditions of input voltage, output voltage,
temperature and load current
8V
≤
V
IN
≤
40V
T
j
= +25°C
T
j
= T
MIN
to T
MAX
1V
≤
V
C
≤
4V
CONDITIONS
T
j
= +25°C
T
j
= +25°C
T
j
= +25°C
T
j
= +25°C
100
0.6
MIN
TYP MAX
2000
3000 5000 9000
140
1.0
0.5
225
1.7
2
UNITS
V/V
µmho
µA
mA
µA
V
%
%/V
V
mV/°C
2.5
4.0
°C/W
MAX724/MAX726
2.155 2.210 2.265
±0.5 ±1.5
±1.0
±2.5
0.005 0.02
1.5
-4
Note 1:
Do not exceed switch-to-input voltage limitation.
Note 2:
For switch currents between 1A and 5A (2A for MAX726), maximum switch-on voltage can be calculated via linear
interpolation.
Note 3:
By setting the feedback pin (FB) to 2.5V, the V
C
pin is forced to its low clamp level and the switch duty cycle is forced to
zero, approximating the zero load condition.
Note 4:
For proper regulation, total voltage from V
IN
to GND must be
≥
8V after start-up.
Note 5:
To avoid extremely short switch-on times, the switch frequency is internally scaled down when V
FB
is less than 1.3V. Switch-
current limit is tested with V
FB
adjusted to give a 1µs minimum switch-on time.
Note 6:
Guaranteed, not production tested.
__________________________________________Typical Operating Characteristics
MAX724
STEP-DOWN CONVERTER EFFICIENCY
vs. OUTPUT CURRENT
110
CIRCUIT OF FIGURE 2
100
SUPPLY CURRENT (mA)
EFFICIENCY (%)
90
80
70
60
50
0
1
2
3
4
5
6
OUTPUT CURRENT (A)
V
OUT
= 5V, V
IN
= 15V
V
OUT
= 12V, V
IN
= 20V
16
QUIESCENT SUPPLY CURRENT (mA)
14
12
10
8
6
4
2
0
-40 -25
0
25
50
75
100
125
JUNCTION TEMPERATURE (°C)
CIRCUIT OF FIGURE 2
V
IN
= 25V, V
OUT
= 5V
I
OUT
= 1mA
SUPPLY CURRENT
vs. JUNCTION TEMPERATURE
20
18
16
14
12
10
8
6
4
2
0
0
QUIESCENT SUPPLY CURRENT
vs. INPUT VOLTAGE
DEVICE NOT SWITCHING
V
C
= 1V
10
20
30
40
V
IN
INPUT VOLTAGE (V)
_______________________________________________________________________________________
3
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
