Rainbow Electronics MAX15038 - Manual (Page 11)

MAX15038
C10
0.1
µF
C6
22 µF OUTPUT
1.8V, 4A
INPUT
2.9V TO 5.5V
C7
0.1 µF
C5
2.2 µF
BST
LX
OUT
IN
V DD
CTL2
CTL1
PGND
FB
C1
33pF
C2
1500pF
V DD
R1
20k
Ω
R2
2.67k Ω
COMP
L1
0.47 µH
C3
560pF
C4
0.022
µF
R4
49.9k Ω
C8
22
µF
C9
0.01
µF
R3
158 Ω
PWRGD
EN
FREQ
REFIN
SS
GND
MODE
MAX15038
2.2 Ω
C15
1000pF
OPTIONAL
Figure 1. 1MHz, All-Ceramic-Capacitor Design with V IN = 2.9V to 5.5V and V OUT = 1.8V
Detailed Description
The MAX15038 high-efficiency, voltage-mode switching
regulator delivers up to 4A of output current. The
MAX15038 provides output voltages from 0.6V to 0.9 x
V
IN from 2.9V to 5.5V input supplies, making it ideal for
on-board point-of-load applications. The output voltage
accuracy is better than ±1% over load, line, and tem-
perature.
The MAX15038 features a wide switching frequency
range, allowing the user to achieve all-ceramic-capaci-
tor designs and fast transient responses (see Figure 1).
The high operating frequency minimizes the size of
external components. The MAX15038 is available in a
small (4mm x 4mm), lead-free, 24-pin thin QFN pack-
age. The REFIN function makes the MAX15038 an ideal
candidate for DDR and tracking power supplies. Using
internal low-R
DS(ON) (24m
Ω for the low-side n-channel
MOSFET and 31m
Ω for the high-side n-channel
MOSFET) maintains high efficiency at both heavy-load
and high-switching frequencies.
The MAX15038 employs voltage-mode control architec-
ture with a high bandwidth (28MHz) error amplifier. The
voltage-mode control architecture allows up to 2MHz
switching frequency, reducing board area. The op-amp
voltage-error amplifier works with type III compensation
to fully utilize the bandwidth of the high-frequency
switching to obtain fast transient response. Adjustable
soft-start time provides flexibilities to minimize input
startup inrush current. An open-drain, power-good
(PWRGD) output goes high when V
FB reaches 92.5% of
V REFIN and V REFIN is greater than 0.54V.
The MAX15038 provides option for three modes of oper-
ation: regular PWM, PWM mode with monotonic startup
into prebiased output, or skip mode with monotonic
startup into prebiased output.
Typical Application Circuit
4A, 2MHz Step-Down Regulator
with Integrated Switches
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