MAX5073ETI+ Maxim Integrated Products, MAX5073ETI+ Datasheet - Page 17

• Manufacturer Part Number: MAX5073ETI+
• Description: IC CONV BUCK/BOOST 28-TQFN
• Manufacturer: Maxim Integrated Products
• Type: Step-Down (Buck), Step-Up (Boost)r

Specifications of MAX5073ETI+

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 2
• Voltage - Output: 0.8 ~ 28 V
• Current - Output: 1A, 2A
• Frequency - Switching: 200kHz ~ 2.2MHz
• Voltage - Input: 4.5 ~ 23 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-TQFN Exposed Pad
• Power - Output: 2.76W
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The allowable output ripple voltage and the maximum
deviation of the output voltage during step load currents
determines the output capacitance and its ESR.
The output ripple is comprised of ∆V
capacitor discharge) and ∆V
of the capacitor). Use low-ESR ceramic or aluminum
electrolytic capacitors at the output. For aluminum
electrolytic capacitors, the entire output ripple is con-
tributed by ∆V
late the ESR requirement and choose the capacitor
accordingly. If using ceramic capacitors, assume the
contribution to the output ripple voltage from the ESR
and the capacitor discharge are equal. Calculate the
output capacitance and ESR required for a specified rip-
ple using the following equations:
where
where ∆I
culated above and f
switching frequency.
The allowable deviation of the output voltage during
fast transient loads also determines the output capaci-
tance and its ESR. The output capacitor supplies the
step load current until the controller responds with a
greater duty cycle. The response time (t
depends on the closed-loop bandwidth of the convert-
er. The high switching frequency of MAX5073 allows for
higher closed-loop bandwidth, reducing t
and the output capacitance requirement. The resistive
drop across the output capacitor ESR and the capaci-
tor discharge causes a voltage droop during a step
load. Use a combination of low-ESR tantalum and
ceramic capacitors for better transient load and
ripple/noise performance. Keep the maximum output volt-
age deviation above the tolerable limits of the electronics
2.2MHz, Dual-Output Buck or Boost Converter
L
is the peak-to-peak inductor current as cal-
ESR
∆
C
V
OUT
O RIPPLE
. Use the ESR
______________________________________________________________________________________
_
ESR
=
SW
OUT
8
is the individual converter’s
×
≅
=
∆
∆
ESR
V
∆
∆
V
Q
V
∆
ESR
I
OUT
L
ESR
I
L
×
(caused by the ESR
Output Capacitors
+
f
SW
equation to calcu-
Q
∆
V
(caused by the
Q
with Internal Power MOSFETs
RESPONSE
RESPONSE
)
being powered. When using a ceramic capacitor,
assume 80% and 20% contribution from the output
capacitance discharge and the ESR drop, respectively.
Use the following equations to calculate the required ESR
and capacitance value:
where I
response time of the controller. Controller response
time depends on the control-loop bandwidth.
The MAX5073 can be configured for step-up conversion
since the internal MOSFET can be used as a low-side
switch. Use the following equations to calculate the
inductor (L
itor (C
Choose the minimum inductor value so the converter
remains in continuous mode operation at minimum out-
put current (I
where
and I
The V
diode, D is the duty cycle, and V
across the internal switch. Select the inductor with low DC
resistance and with a saturation current (I
er than the peak switch current limit of 4.5A and 2.2A of
converter 1 and converter 2, respectively.
OMIN
D
OUT
is the forward voltage drop of the external Schottky
STEP
) when using the converter in boost operation.
MIN
L
= 0.25 x I
MIN
C
OMIN
is the load step and t
), input capacitor (C
OUT
=
D
ESR
).
2
=
=
O
×
I
V
STEP
V
OUT
O
O
V
f
SW
2
+
+
IN
V
V
=
×
D
D
×
×
∆
∆
I
−
−
STEP
t
V
V
RESPONSE
V
D
V
ESR
V
Q
O
IN
DS
DS
IN
×
Boost Converter
×
), and output capac-
η
is the voltage drop
I
RESPONSE
OMIN
SAT
) rating high-
Inductor
is the
17