MAX1515 Datasheet, PDF (12/24 Pages) Maxim Integrated Products – Low-Voltage, Internal Switch, Step-Down/DDR Regulator

Low-Voltage, Internal Switch,
Step-Down/DDR Regulator
PIN
18
19
20
21, 22
23, 24
NAME
FBSEL1
SKIP
BST
LX
IN
Pin Description (continued)
FUNCTION
Used with FBSEL0 to set the output voltage of the step-down regulator when MODE = GND.
Connect to GND if MODE = V_CC.
Pulse-Skipping Control Input. Connect to V_CC for low-noise, forced-PWM mode. Connect to GND to
enable automatic pulse-skipping operation.
Boost Flying-Capacitor Connection. Connect an external 0.01µF capacitor as shown in the standard
application circuit (Figure 1).
Inductor Switched Node. LX is the connection for the source of the high-side NMOS power switch
and drain of the low-side NMOS synchronous-rectifier switch. Connect both LX pins together.
Power Input. Supply voltage input for the switching regulator. Connect to a +1.3V to +3.6V supply
voltage. Connect both IN pins together.
Table 1. Component Selection for Standard Applications
COMPONENT
±2A AT 1.25V_OUT
DDR MODE (MODE = V_CC)
±2A AT 0.9V_OUT
DDR MODE (MODE = V_CC)
Input Voltage (V_IN)
Output Voltage (V_OUT)
2.3V to 2.7V
1.25V
1.6V to 2.0V
0.9V
C_IN, Input Capacitor
33µF, 6.3V, ceramic
TDK C3225XR0J336V
33µF, 6.3V, ceramic
TDK C3225XR0J336V
Switching Frequency (f_SW)
L, Inductor
250kHz
2.5µH, 4.5A, Sumida
CDRH8D28-2R5
500kHz
1.2µH, 6.8A, Sumida
CDR7D28MN-1R2
250kHz
2.5µH, 4.5A, Sumida
CDRH8D28-2R5
500kHz
1.2µH, 6.8A, Sumida
CDR7D28MN-1R2
C_OUT, Output Capacitor
330µF, 18mΩ
Sanyo 2R5TPE330MI
POSCAP
220µF, 18mΩ
Sanyo 2R5TPE220MI
POSCAP
330µF, 18mΩ
Sanyo 2R5TPE330MI
POSCAP
220µF, 18mΩ
Sanyo 2R5TPE220MI
POSCAP
R_TOFF
221kΩ, 1%
110kΩ, 1%
221kΩ, 1%
110kΩ, 1%
Table 2. Component Suppliers
SUPPLIER
Coilcraft
Coiltronics
Kemet
Panasonic
Sanyo
Sumida
Taiyo Yuden
TDK
TOKO
WEBSITE
www.coilcraft.com
www.coiltronics.com
www.kemet.com
www.panasonic.com
www.sanyo.com
www.sumida.com
www.t-yuden.com
www.component.tdk.com
www.tokoam.com
Standard Application Circuit
The MAX1515 standard application circuit (Figure 1)
generates a tracking output voltage and a reference
buffer output required for DDR termination regulators.
See Table 1 for component selections. Table 2 lists the
component manufacturers.
Detailed Description
The MAX1515 synchronous, current-mode, constant
off-time, PWM DC-DC converter steps down an input
voltage (V_IN) from +1.3V to +3.6V to an output voltage
from +0.5V to +2.7V. The MAX1515 output delivers up
to 3A of continuous current. Internal 40mΩ NMOS
power switches improve efficiency, reduce component
count, and eliminate the need for a boost diode or any
external Schottky diodes (Figure 2).
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