MAX1790 Maxim, MAX1790 Datasheet - Page 5

• Manufacturer Part Number: MAX1790
• Description: Low-Noise Step-Up DC-DC Converter
• Manufacturer: Maxim

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