MAX724/MAX726
5A/2A Step-Down, PWM,
Switch-Mode DC-DC Regulators
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 25V, T
j
= T
MIN
to T
MAX
, unless otherwise noted.)
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.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Error-Amplifier Voltage Gain
1V ≤ V
C
≤ 4V T
j
= +25°C
2000 V/V
Error-Amplifier Transconductance
T
j
= +25°C
3000 5000 9000 µmho
Error-Amplifier Source Current
V
FB
= 2V
T
j
= +25°C
100 140 225 µA
Reference Voltage Tolerance
VREF (nominal) = 2.21V
T
j
= +25°C
±0.5 ±1.5
%
Reference Voltage
V
C
= 2V
2.155 2.210 2.265 V
Feedback Pin Bias Current
V
FB
= VREF
0.5 2 µA
Error-Amplifier Sink Current
V
FB
= 2.5V
T
j
= +25°C
0.6 1.0 1.7 mA
T
j
= T
MIN
to T
MAX
-4 mV/°C
VC Voltage at 0% Duty Cycle
T
j
= +25°C
1.5 V
Reference Voltage Line Regulation
8V ≤ V
IN
≤ 40V
0.005 0.02 %/V
±1.0 ±2.5
MAX724 2.5
°C/W
Thermal Resistance,
Junction to Case (Note 6)
All conditions of input voltage, output voltage,
temperature and load current
MAX726 4.0
__________________________________________Typical Operating Characteristics
110
50
06
MAX724
STEP-DOWN CONVERTER EFFICIENCY
vs. OUTPUT CURRENT
60
100
OUTPUT CURRENT (A)
EFFICIENCY (%)
4
80
70
135
90
2
CIRCUIT OF FIGURE 2
V
OUT
= 12V, V
IN
= 20V
V
OUT
= 5V, V
IN
= 15V
16
4
-40 100
SUPPLY CURRENT
vs. JUNCTION TEMPERATURE
6
14
JUNCTION TEMPERATURE (°C)
SUPPLY CURRENT (mA)
50
10
8
-25 25 75
12
0
CIRCUIT OF FIGURE 2
V
IN
= 25V, V
OUT
= 5V
I
OUT
= 1mA
2
0
125
20
8
0
QUIESCENT SUPPLY CURRENT
vs. INPUT VOLTAGE
10
18
V
IN
INPUT VOLTAGE (V)
QUIESCENT SUPPLY CURRENT (mA)
40
14
12
10 30
16
20
6
4
V
C
= 1V
DEVICE NOT SWITCHING
2
0
(6 strony)
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