Datasheet

(Circuits of Figures 1 (MAX1836) and 2 (MAX1837), V
IN
= 12V, SHDN = IN, T
A
= -40°C to +85°C, unless otherwise noted.) (Note 4)
Note 2: When using the shutdown input, the maximum output voltage allowed with external feedback is 5.5V. If the output voltage is
set above 5.5V, connect shutdown to the input.
Note 3: Shutdown input minimum slew rate (rising or falling) is 10V/ms.
Note 4: Specifications to -40°C are guaranteed by design, not production tested.
(Circuits of Figures 1 (MAX1836) and 2 (MAX1837), V
IN
= 12V, SHDN = IN, T
A
= +25°C.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
LX Zero-Crossing Threshold -75 +75 mV
Shutdown Input Threshold V
SHDN
V
IN
= 4.5V to 24V (Note 3) 0.8 2.4 V
Shutdown Leakage Current I
SHDN
V
SHDN
= 0 or 24V -1 +1 µA
100
95
90
85
80
70
0.1 10 1001 1000
MAX1836EUT33
EFFICIENCY vs. LOAD CURRENT
MAX1836/7 toc02
LOAD CURRENT (mA)
EFFICIENCY (%)
75
V
IN
= 9V
V
IN
= 12V
V
IN
= 5V
FIGURE 1
V
OUT
= 3.3V
3.27
3.29
3.28
3.31
3.30
3.32
3.33
0 150 20050 100 250 300 350
MAX1837EUT33
OUTPUT VOLTAGE vs. LOAD CURRENT
MAX1836/7 toc03
LOAD CURRENT (mA)
OUTPUT VOLTAGE (V)
V
IN
= 9V
V
IN
= 5V
V
IN
= 12V
FIGURE 2
100
95
90
85
80
70
0.1 10 1001 1000
MAX1837EUT33
EFFICIENCY vs. LOAD CURRENT
MAX1836/7 toc04
LOAD CURRENT (mA)
EFFICIENCY (%)
75
V
IN
= 9V
V
IN
= 12V
V
IN
= 5V
FIGURE 2
V
OUT
= 3.3V
0
40
20
100
80
60
160
140
120
180
0 100 15050 200 250 300 350
MAX1837EUT33
SWITCHING FREQUENCY vs. LOAD CURRENT
MAX1836/7 toc05
LOAD CURRENT (mA)
FREQUENCY (kHz)
V
IN
= 9V
V
IN
= 5V
V
IN
= 12V
FIGURE 2
V
OUT
= 3.3V
3.27
3.29
3.28
3.31
3.30
3.32
3.33
0 4 8 12 16 20 24
MAX1837EUT33
OUTPUT VOLTAGE vs. INPUT VOLTAGE
MAX1836/7 toc06
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
I
OUT
= 10mA
I
OUT
= 200mA
FIGURE 2
V
OUT
= 3.3V
L1 = 47µH
3.27
3.29
3.28
3.31
3.30
3.32
3.33
0 10050 150 200
MAX1836EUT33
OUTPUT VOLTAGE vs. LOAD CURRENT
MAX1836/7 toc01
LOAD CURRENT (mA)
OUTPUT VOLTAGE (V)
V
IN
= 5V
V
IN
= 9V to 12V
FIGURE 1
MAX1836/MAX1837 24V Internal Switch, 100% Duty Cycle,
Step-Down Converters
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Electrical Characteristics (continued)
Typical Operating Characteristics