MAX8561ETA+T Maxim Integrated Products, MAX8561ETA+T Datasheet - Page 8

• Manufacturer Part Number: MAX8561ETA+T
• Description: IC DC-DC CONV ADJ 500MA 8-TDFN
• Manufacturer: Maxim Integrated Products
• Type: Step-Down (Buck)r

Specifications of MAX8561ETA+T

• Internal Switch(s): Yes
• Synchronous Rectifier: Yes
• Number Of Outputs: 1
• Voltage - Output: 0.6 ~ 2.5 V
• Current - Output: 500mA
• Frequency - Switching: 4MHz
• Voltage - Input: 2.7 ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-TDFN Exposed Pad
• Power - Output: 1.95W
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

4MHz, 500mA Synchronous Step-Down
DC-DC Converters in Thin SOT and TDFN
Figure 2. Using ODI/ODO to Obtain Two Output Voltages from
the MAX8561
The output capacitor, C
output voltage ripple small and to ensure regulation
loop stability. C
switching frequency. Ceramic capacitors with X5R or
X7R dielectrics are highly recommended due to their
small size, low ESR, and small temperature coefficients.
Due to the unique feedback network, the output capac-
itance can be very low. For most applications, a 2.2µF
capacitor is sufficient. For optimum load-transient per-
formance and very low output ripple, the output capaci-
tor value in µFs should be equal to or larger than the
inductor value in µHs.
The input capacitor, C
drawn from the battery or input power source and
reduces switching noise in the IC. The impedance of
C
Ceramic capacitors with X5R or X7R dielectrics are
highly recommended due to their small size, low ESR,
and small temperature coefficients. Due to the
MAX8560/MAX8561/MAX8562s’ soft-start, the input
capacitance can be very low. For most applications, a
2.2µF capacitor is sufficient.
8
Li+ BATTERY
IN
ON/OFF
1.5/1.0
INPUT
2.2µF
_______________________________________________________________________________________
at the switching frequency should be kept very low.
ODI
GND
SHDN
IN
MAX8561
OUT
PGND
must have low impedance at the
ODO
LX
FB
IN
OUT
, reduces the current peaks
120kΩ
, is required to keep the
Capacitor Selection
100kΩ
150kΩ
Output Capacitor
2.2µH
220pF
Input Capacitor
1.5V OR 1.0V
AT 500mA
OUTPUT
2.2µF
The feed-forward capacitor, C
response, controls the switching frequency, and is criti-
cal in obtaining the best efficiency possible. Choose a
small ceramic X7R capacitor with a value given by:
Select the closest standard value to C
High switching frequencies and relatively large peak cur-
rents make the PC board layout a very important part of
design. Good design minimizes excessive EMI on the
feedback paths and voltage gradients in the ground
plane, both of which can result in instability or regulation
errors. Connect C
inductor and output capacitor as close to the IC as pos-
sible and keep their traces short, direct, and wide.
Connect GND and PGND separately to the ground
plane. The external feedback network should be very
close to the FB pin, within 0.2in (5mm). Keep noisy
traces, such as the LX node, as short as possible. For
the 8-pin TDFN package, connect GND to the exposed
paddle directly under the IC. Figure 4 illustrates an
example PC board layout and routing scheme.
Figure 3. Using the MAX8562 to Control an External Bypass
PFET for a Two-Step V
Li+ BATTERY
ON/OFF
INPUT
2.2µF
HP/LP
GND
SHDN
ODI
IN
MAX8562
C
PGND
PC Board Layout and Routing
IN
ODO
FF
CC
PFET
close to IN and GND. Connect the
=
in CDMA-PA Applications
R
L
LX
FB
1
×
10
Feed-Forward Capacitor
FF
100kΩ
100kΩ
Siemens
, sets the feedback loop
1.5µH
150pF
HP = HIGH-POWER MODE
LP = LOW-POWER MODE
FF
as possible.
1.2V OR V
OUTPUT
2.2µF
BATT