MAX1534ETE+ Maxim Integrated Products, MAX1534ETE+ Datasheet - Page 13

• Manufacturer Part Number: MAX1534ETE+
• Description: IC PWR SUPPLY CONTROLLER 16TQFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX1534ETE+

• Applications: Power Supply Controller
• Voltage - Input: 4.5 ~ 24 V
• Current - Supply: 15µA
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-TQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Supply: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

voltage. For optimum performance, select an inductor
with the lowest possible DC resistance that fits in the
allotted dimensions. Some recommended component
manufacturers are listed in Table 2.
The MAX1534’s buck converter’s maximum output cur-
rent is limited by the peak inductor current. For the typi-
cal application, the maximum output current is
approximately:
For low-input voltages, the maximum on-time can be
reached and the load current is limited by:
Note that any current provided by the linear regulators
comes from the buck regulator and subtracts from the
maximum current that the buck provides for other loads.
Choose the output capacitor to service the maximum
load current with acceptable voltage ripple. The output
ripple has two components: variations in the charge
stored in the output capacitor with each LX pulse, and
the voltage drop across the capacitor’s equivalent
series resistance (ESR) caused by the current into and
out of the capacitor:
The output voltage ripple as a consequence of the ESR
and output capacitance is:
Figure 3. Normal Buck Operation
10V
1A
0
0
V
V
I
OUT3
IN
RIPPLE
I
= 12V, I
OUT3(MAX)
V
RIPPLE(ESR)
High-Efficiency, Triple-Output, Keep-Alive
= 1/2 (V
OUT3
≅ V
______________________________________________________________________________________
= 300mA
Buck Output Capacitor Selection
RIPPLE(ESR)
Power Supply for Notebook Computers
Maximum Buck Output Current
= 1/2 I
4µs/div
IN
- V
= ESR
OUT3
LX (PEAK)(MIN)
+ V
✕
)
✕
I
RIPPLE(C)
PEAK
10µs / L
V
50mV/div
AC-COUPLED
V
10V/div
I
500mA/div
LX
OUT3
LX
where I
Selection). The worst-case ripple occurs at no load.
These equations are suitable for initial capacitor selec-
tion, but final values should be set by testing a proto-
type or evaluation circuit. As a general rule, a smaller
amount of charge delivered in each pulse results in
less output ripple. Since the amount of charge deliv-
ered in each oscillator pulse is determined by the
inductor value and input voltage, the voltage ripple
increases with larger inductance, and as the input volt-
age decreases. See Table 1 for recommended capaci-
tor values and Table 2 for recommended component
manufacturers.
The input filter capacitor reduces peak currents drawn
from the power source and reduces noise and voltage
ripple on the input caused by the circuit’s switching.
The input capacitor must meet the ripple-current
requirement (I
defined by the following equation:
For most applications, nontantalum chemistries (ceram-
ic, aluminum, polymer, or OSCON) are preferred due to
their robustness to high inrush currents typical of sys-
tems with low-impedance battery inputs. Choose an
Figure 4. Adjustable Output Voltages
V
V
OUT1
OUT2
V
RIPPLE C
R
R
R
R
PEAK
BOT1
BOT2
TOP1
TOP2
I
RMS
( )
=
is the peak inductor current (see Inductor
OUT1
FB1
OUT2
FB2
RMS
I
OUT
=
L
2
) imposed by the switching current
×
3
C
MAX1534
V
(
×
I
IN
PEAK
OUT
GND
Buck Input Capacitor Selection
V
OUT
3
−
×
PRESET
3
I
V
OUT
FB3
OUT
LX
IN



4
3
3

 ×

3
)
2



V
V
OUT
V
IN
V
IN
IN
R
R
= +7V TO +24V
TOP3
BOT3
−
3
V
V
IN
−
OUT
1
3
V



OUT3
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