Datasheet
MAX16962
4A, 2.2MHz, Synchronous Step-Down
DC-DC Converter
9Maxim Integrated
Applications Information
Setting the Output Voltage
Connect OUTS to V
OUT
for factory programmed output
voltage.(See the Selector Guide.) To set the output to
other voltages between 0.8V and 3.6V, connect a resis-
tive divider from output (V
OUT
) to OUTS to GND (Figure
2). Select R2 (OUTS to GND resistor) less than or equal
to 100kI. Calculate R1 (V
OUT
to OUTS resistor) with the
following equation:
OUT
OUTS
V
R1 R2 1
V
= −
where V
OUTS
= 800mV (see the Electrical Characteristics
table).
The external feedback resistive divider must be frequency
compensated for proper operation. Place a capacitor
across each resistor in the resistive divider network.
Use the following equation to determine the value of the
capacitors:
=
R2
C1 10pF
R1
Inductor Selection
Three key inductor parameters must be specified for
operation with the MAX16962: inductance value (L),
inductor saturation current (I
SAT
), and DC resistance
(R
DCR
). Use the following formulas to determine the
minimum inductor value:
( )
=−× ×
×
OUT_
MIN1 IN OUT_
IN OP
V
3
L V V ( )( )
V f 4A
where f
OP
is the operating frequency. This value is
2.2MHz unless externally synchronized to a different
frequency.
The next equation ensures that the inductor curent
downslope is less than the internal slope compensation.
For this to be the case, the following equation needs to
be satisfied:
− ≥
m2
m
2
where m2 is the inductor current downslope:
OUT_V
L
and -m is the slope compensation:
µ
MAX0.8 xI
s
Solving for L:
µ
= ×
×
MIN2 OUT
s
LV
1.6 4A
The equation that provides the bigger inductor value
must be chosen for proper operation:
L
MIN
= max(L
MIN1
, L
MIN2
)
The maximum inductor value recommended is twice the
chosen value from the above formula.
L
MAX
= 2 x L
MIN
Figure 2. Adjustable Output Voltage Setting
Table 1. Inductor Values vs. (V
IN
- V
OUT
)
V
IN
- V
OUT
(V)
5.0 to 3.3 5.0 to 2.5 5.0 to 1.5 3.3 to 0.8
INDUCTOR (µH)
0.8 0.6 0.47 0.33
MAX16962
OUTS
R1
R2
C1
V
OUT