MAX1945SEUI Maxim Integrated Products, MAX1945SEUI Datasheet - Page 10

• Manufacturer Part Number: MAX1945SEUI
• Description: DC/DC Switching Regulators 1MHz 1% 6A Step-Down PWM
• Manufacturer: Maxim Integrated Products

Specifications of MAX1945SEUI

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

1MHz, 1% Accurate, 6A Internal Switch
Step-Down Regulators
10
(V
20, 22, 24,
4, 6, 8, 10
3, 5, 7, 9,
IN
PIN
= V
26
11
12
13
14
15
16
17
18
______________________________________________________________________________________
1
2
VOLTAGE MARGINING (9%)
CC
= 5V, V
SYNCOUT
400µs/div
NAME
COMP
FBSEL
SYNC
GND
V
V
BST
REF
LX
FB
IN
DD
CC
OUT
= 1.8V, I
Bootstrap Voltage. High-side driver supply input. Connect a 0.1µF capacitor from BST to LX. Connect a
Schottky diode from IN to BST. A 1N4148 diode can be used for 5V input to reduce cost.
Low-Side Driver Supply Voltage
Inductor Connection. Connect an inductor between LX and the regulator output. Connect all LX pins
together close to the device.
Power-Supply Voltage. Input voltage ranges from 2.6V to 5.5V. Bypass with 3 x 22µF ceramic capacitors
in parallel to PGND (see the Input Capacitor Selection section).
Supply-Voltage Input. V
GND with 0.1µF.
Analog Ground
Reference. Bypass REF with 0.22µF capacitor to GND. REF tracks the soft-start ramp voltage margining
and is pulled to GND when the output shuts down.
Regulator Compensation. Connect a series RC network from COMP to GND. COMP is pulled to GND
when the output shuts down (see the Compensation Design section).
Feedback Input. When FBSEL = High-Z, use an external resistor divider from the output to set the voltage
from 0.8V to 85% of V
regulation to 2.5V when FBSEL = V
Feedback Select Input. The device regulates to an output of 0.8V when FBSEL is left unconnected. The
device regulates to an output of 1.8V when FBSEL = GND and regulates to an output of 2.5V when
FBSEL = V
Synchronization/Frequency Select. Connect SYNC to GND for 500kHz operation, to V
operation, or connect to an external clock at 400kHz to 1.2MHz.
Synchronization Output. SYNCOUT provides a frequency output synchronized 180 degrees out-of-phase
to the operating frequency of the device.
MAX1945 toc18
OUT
V
2V/div
V
200mV/div
CTL1
OUT
= 6A, f
CC
.
SW
= 500kHz, V
SHORT-CIRCUIT INDUCTOR CURRENT
Typical Operating Characteristics (continued)
IN
CC
. Connect FB to the output for regulation to 1.8V when FBSEL = 0, or for
powers the device. Connect a 10Ω resistor from IN to V
DD
100ms/div
CC
= V
.
CC
, and T
MAX1945 toc19
FUNCTION
A
= +25°C, unless otherwise noted.)
V
500mV/div
I
5A/div
LX
OUT
SHORT-CIRCUIT INDUCTOR CURRENT
(EXPANDED TIME)
Pin Description
10µs/div
CC
. Bypass V
CC
for 1MHz
MAX1945 toc20
CC
V
500mV/div
I
10A/div
V
2V/div
to
LX
OUT
LX