Rainbow Electronics MAX1790 - Manual (Page 5)

MAX1790
Low-Noise Step-Up DC-DC Converter
_______________________________________________________________________________________ 5
2ms/div
STARTUP WAVEFORM WITH
SOFT-START
MAX1790-10
CH1
CH2
CH3
CH1 = SHDN, 5V/div
CH2 = V
OUT, 5V/div
CH3 = INDUCTOR CURRENT, 500mA/div
V
OUT = 12V, I OUT = 200mA, f OSC = 640kHz,
C SS = 0.027 µF
CH1
CH2
CH3
CH1 = LX SWITCHING WAVEFORM, 5V/div
CH2 = OUTPUT VOLTAGE, AC-COUPLED, 200mV/div
CH3 = INDUCTOR CURRENT, 1A/div
V
OUT = 12V, I OUT = 200mA, f OSC = 640kHz, L = 10 µH;
C OUT = 33 µF + 0.1µF
500ns/div
SWITCHING WAVEFORM
MAX1790-11
0
400
200
800
600
1000
1200
1600
1400
1800
3.0 3.4 3.6 3.8 3.2 4.0 4.2 4.4 4.8 4.6 5.0
MAXIMUM OUTPUT CURRENT
vs. INPUT VOLTAGE
MAX1790-12
INPUT VOLTAGE (V)
MAXIMUM OUTPUT CURRENT (mA)
f OSC = 640kHz
V OUT = 12V
V OUT = 5V
Typical Operating Characteristics (continued)
(Circuit of Figure 1, V IN = 3.3V, f OSC = 640kHz, T A = +25°C, unless otherwise noted.)
500mA
20mA
CH1 = LOAD CURRENT, 500mA/div
CH2 = OUTPUT VOLTAGE, AC-COUPLED, 200mV/div
CH3 = INDUCTOR CURRENT, 1A/div
V
OUT = 5V, f OSC = 640kHz, C OUT = 47 µF + 0.1µF
100 µs/div
LOAD-TRANSIENT RESPONSE
MAX1790-07 CH1
CH2
CH3
R COMP = 62k Ω
C COMP = 820pF
C COMP2 = 56pF
100 µs/div
STARTUP WAVEFORM WITHOUT
SOFT-START
MAX1790-08
CH1
CH2
CH3
CH1 = SHDN, 5V/div
CH2 = OUTPUT VOLTAGE, 5V/div
CH3 = INDUCTOR CURRENT, 1A/div
V
IN = 3.3V, V OUT = 12V, I OUT = 10mA, f OSC = 640kHz
NO SOFT-START CAPACITOR, C OUT = 33 µF
1ms/div
STARTUP WAVEFORM WITH
SOFT-START
MAX1790-09
CH1
CH2
CH3
CH1 = SHDN, 5V/div
CH2 = OUTPUT VOLTAGE, 5V/div
CH3 = INDUCTOR CURRENT, 200mA/div
V
OUT = 12V, I OUT = 10mA, f OSC = 640kHz,
C SS = 0.027 µF, C
OUT = 33 µF