MAX1896EUT#TG16 Maxim Integrated Products, MAX1896EUT#TG16 Datasheet - Page 7

• Manufacturer Part Number: MAX1896EUT#TG16
• Description: IC DC-DC CONV STEP UP SOT23-6
• Manufacturer: Maxim Integrated Products
• Type: Step-Up (Boost)r

Specifications of MAX1896EUT#TG16

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 2.6 ~ 13 V
• Current - Output: 500mA
• Frequency - Switching: 1.4MHz
• Voltage - Input: 2.6 ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: SOT-23-6
• Power - Output: 727mW
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The inductance (H) value is then given by:
The output diode should be rated to handle the output
voltage and the peak switch current. Make sure the
diode’s peak current rating is at least I
breakdown voltage exceeds V
recommended. If a junction rectifier is used, it must be
an ultra-fast type (t
in the rectifier.
The MAX1896 operates with both tantalum and ceramic
output capacitors. When using tantalum capacitors, the
zero caused by the ESR of the tantalum is used to
ensure stability. When using ceramic capacitors, the
zero due to the ESR will be at too high a frequency to
be useful in stabilizing the control loop. When using
ceramic capacitors, use a feedforward capacitor to
increase the phase margin, improving the control-loop
stability. Figure 3 shows the circuit with ceramic capac-
itors and the feedforward capacitor, C
lowing equation to determine the value of the
feedforward capacitor:
where:
R1 = see Figure 3, (Ω)
C
capacitor on the output bus, (Farads). See Figure 3.
V
V
OUT
IN
OUT
= input voltage, (V).
= output voltage, (V)
= total output capacitance including any bypass
k
L
Input and Output Capacitor Selection
1
C
=
=
FF
7 14
[
V
V
.
IN MIN
OUT
=
(
R
x
k
_______________________________________________________________________________________
2
1
rr
1
10
)
2
x LIR x I
< 50ns) to prevent excessive loss
x
−
4
x




C
with units of
η
OUT
x V
(
OUT MAX
OUT.
V
x V
OUT
IN
(
Diode Selection
OUT
Schottky diodes are



−
Ω
)
2
V
FF
PK
IN MIN




A
x f
x F
. Use the fol-
0 5
(
.
and that its
OSC



1.4MHz SOT23 Current-Mode
0 5
)
)]
.
Step-Up DC-DC Converter
The MAX1896 operates with an adjustable output from
V
output to FB (see Typical Operating Circuit). Choose a
value for R2 between 10kΩ and 50kΩ. Calculate R1
using the equation:
where V
1.24V. Connect the resistive-divider as close to the IC
as possible.
The soft-start capacitor should be large enough that the
current limit does not reach final value before the output
has reached regulation. Calculate C
where:
k
V
I
I
V
The soft-start duration (t
rent limit to reach its final value. The soft-start duration
can be calculated by the equation:
where:
OUT
INRUSH
2
IN
OUT
IN
= 21 x 10
= minimum input voltage, (V)
to 13V. Connect a resistive voltage-divider from the
= maximum output current during power-up stage, (A)
= maximum output voltage, (V)
FB
= peak inrush current allowed, (A)
, the step-up regulator feedback set point, is
C




-6
V
SS
R
IN
, (S)
1
>
x I
V
=
OUT
INRUSH
k
k
R x
3
2
t
Setting the Output Voltage
2
ss
2
= 6.67
x C
= k
SS
−



V
V
) is the time it takes the cur-
OUT
3
−
V
IN
OUT
FB
Soft-Start Capacitor
I
OUT
C
10
x V
x
SS
−
5
1
OUT
Ω



x V
SS
to be:
OUT




7