MAX1556_10 Datasheet, PDF (5/12 Pages) Maxim Integrated Products – 16μA IQ, 1.2A PWM Step-Down DC-DC Converters

16µA I_Q, 1.2A PWM DC-DC
Step-Down Converters
Typical Operating Characteristics (continued)
(V_IN = V_INP = 3.6V, D1 = D2 = SHDN = IN, Circuits of Figures 2 and 3, T_A = +25°C, unless otherwise noted.)
LIGHT-LOAD SWITCHING WAVEFORMS
MAX1556/7 toc10
EXTERNAL FEEDBACK
SWITCHING WAVEFORMS
MAX1556/7 toc10b
20mV/div
V_OUT
AC-COUPLED
V_LX
2V/div
V_LX
2V/div
0
0
200mA/div _ILX
200mA/div
I_LX
0
0
V_IN = 5V, V_OUT = 3.3V, I_OUT = 500mA
4µs/div
2µs/div
SOFT-START/SHUTDOWN WAVEFORMS
MAX1556/7 toc11
V_SHDN
5V/div
0
V_OUT
C_SS = 470pF
R_LOAD = 4Ω
I_LX
1V/div
0
500mA/div
0
500mA/div
I_IN
0
100µs/div
SOFT-START RAMP TIME vs. C_SS
10
LOAD TRANSIENT
MAX1556/7 toc13
50mV/div
V_OUT
AC-COUPLED
1
0.1
0
500 1000 1500 2000 2500
C_SS (pF)
500mA/div
I_OUT
0
I_OUTMIN = 20mA
20µs/div
LOAD TRANSIENT
MAX1556/7 toc14
50mV/div ^VIN
V_OUT
AC-COUPLED
V_OUT
500mA/div
0
I_OUT
I_LX
I_OUTMIN = 180mA
20µs/div
LINE TRANSIENT
MAX1556/7 toc15
4V
3.5V
40µs/div
10mV/div
AC-COUPLED
200mA/div
0
BODE PLOT
40
240 ^{MAX1556/7 toc16}
30
210
20
180
10
150
0
120
-10
90
-20
0dB
60
-30
PHASE MARGIN = 53°
30
-40
0
-50
C_OUT = 22µF, R_LOAD = 4Ω
-60
0.1
1
10
100
FREQUENCY (kHz)
-30
-60
1000
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