Rainbow Electronics MAX1765 - Manual (Page 8)

MAX1765
800mA, Low-Noise, Step-Up DC-DC Converter
with 500mA Linear Regulator
8 _______________________________________________________________________________________
LOAD TRANSIENT RESPONSE
MAX1765 toc14
A: I OUT , 500mA/div
B: V
OUT
,100mV/div
A
B
50 µs/div
V IN = +2.4V, V OUT = +3.3V, I OUT = 0 TO 500mA
Typical Operating Characteristics (continued)
(T A = +25°C, unless otherwise noted.)
0
-10
-20
-30
-40
-50
-60
-70
-80
0.1 10 100 1 1000
LDO PSRR vs. FREQUENCY
(100Hz TO 1MHz)
MAX1765 toc10
FREQUENCY (kHz)
LDO PSRR (dB)
16
0.1 1 10
BOOST FOLLOWED BY LDO
OUTPUT NOISE SPECTRUM
0
MAX1765 toc11
FREQUENCY (MHz)
NOISE (mV
RMS
)
4
2
8
10
6
12
14
V IN = +2.4V
V OUT = +3.3V
LINE TRANSIENT RESPONSE
(DC-DC)
MAX1765 toc12
100 µs/div
A: V
IN
, 500mV/div
B: V
OUT
, 1mV/div, AC-COUPLED
A
B
V
OUT
= +3.3V, I = 0mA
V
IN
= +1.4V TO +2.4V
LINE TRANSIENT RESPONSE
(LINEAR)
MAX1765 toc13
A: V IN , 2V/div
B: V OUT , 5mV/div, AC-COUPLED
A
B
I = 0mA, V IN = +3V TO +5V, V OUT = +3.3V
TURN-ON WAVEFORMS
NO SOFT-START COMPONENTS
MAX1765 toc15a
A: 0NA, 5V/div
B: V
OUT , 2V/div
C: INPUT CURRENT, 1A/div
A
B
C
SOFT-START WAVEFORMS
(R SS = 500k Ω, C
SS = 0.1 µF)
MAX1765 toc15b
A: 0NA, 5V/div
B: INPUT CURRENT, 100mA/div
C: V
OUT , 1V/div
A
B
C
2.5ms/div
HEAVY-LOAD SWITCHING WAVEFORMS
(I OUT = 650mA, V IN = +2.4V, V OUT = 3.3V)
MAX1765 toc16
A: LX, 5V/div
B: INDUCTOR CURRENT, 200mA/div
C: OUTPUT RIPPLE, 50mV/div, AC-COUPLED
A
B
C
500ns/div