MAX5098AATJ+T Maxim Integrated Products, MAX5098AATJ+T Datasheet - Page 18

• Manufacturer Part Number: MAX5098AATJ+T
• Description: IC CONV BUCK/BOOST DL 32TQFN-EP
• Manufacturer: Maxim Integrated Products
• Type: Step-Down (Buck), Step-Up (Boost)r

Specifications of MAX5098AATJ+T

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 2
• Voltage - Output: 0.8 ~ 0.85 V, 4.5 ~ 28 V
• Current - Output: 1A, 2A
• Frequency - Switching: 200kHz ~ 2.2MHz
• Voltage - Input: 4.5 ~ 19 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 32-TQFN Exposed Pad
• Power - Output: 2.76W
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Dual, 2.2MHz, Automotive Buck or Boost
Converter with 80V Load-Dump Protection
The controller generates the clock signal by dividing
down the internal oscillator f
nal when driven by an external oscillator. The switching
frequency equals half the internal oscillator frequency
(f
by a resistor (R
find R
use the formulas:
A rising clock edge on SYNC is interpreted as a syn-
chronization input. If the SYNC signal is lost, the inter-
nal oscillator takes control of the switching rate,
returning the switching frequency to that set by R
When an external synchronization signal is used, R
must be selected such that f
f
form, phase shifted by 180°. If the MAX5098A is run-
ning without external synchronization, f
internal oscillator frequency f
Although the MAX5098A converter can operate from
input supplies ranging from 5.2V to 19V, the input volt-
age range can be effectively limited by the MAX5098A
duty-cycle limitations for a given output voltage. The
maximum input voltage is limited by the minimum on-
time (t
where t
limited by the maximum duty cycle (D
where V
inductor discharge path, which includes the forward
voltage drop (V
18
SYNC
SW
______________________________________________________________________________________
V
= f
R
R
IN MIN
OSC
ON(MIN)
clock signal is applied, f
OSC
OSC
ON(MIN)
(
OSC
DROP1
for each converter switching frequency f
( )
( )
)
/2). The internal oscillator frequency is set
k
k
=
Setting the Switching Frequency
Ω
Ω
):
⎡
⎢
⎣
V
OSC
is the total parasitic voltage drops in the
Applications Information
D
is 100ns. The minimum input voltage is
V
IN MAX
=
=
) of the rectifier, the series resistance
OUT
(
f
f
SW
SW
) connected from OSC to SGND. To
D
(
(
+
MAX
12 184
10 721
MHz
MHz
)
V
Effective Input Voltage Range
≤
.
DROP
.
t
ON MIN
)
)
0 920
0 973
OSC
OSC
.
.
(
1
V
CKO
SW
⎤
⎥ +
⎦
OUT
.
or the SYNC input sig-
(
(
)
f
f
V
SW
SW
×
= 1/2 f
Buck Converter
DROP
equals f
f
SW
MAX
<
≥
CKO
1 25
1 25
2
.
.
= 0.82):
SYNC
−
SYNC
MHz
MHz
V
equals the
DROP
. When
)
)
wave-
1
OSC
OSC
SW
,
.
of the inductor, and the PCB resistance. V
total resistance in the charging path that includes the
on-resistance of the high-side switch, the series resis-
tance of the inductor, and the PCB resistance.
For 0.8V or greater output voltages, connect a voltage-
divider from OUT_ to FB_ to SGND (Figure 3). Select R
(FB_ to SGND resistor) to between 1kΩ and 20kΩ.
Calculate R
equation:
where V
table) and V
operation).
For output voltages below 0.8V, set the MAX5098A out-
put voltage by connecting a voltage-divider from OUT_
to FB_ to BYPASS (Figure 3). Select R
resistor) in the 50kΩ range. Calculate R
lowing equation:
where V
Characteristics table), and V
V
Figure 3. Adjustable Output Voltage
FB_
MAX5098A
.
SOURCE_
FB_
FB_
FB_
V
OUT_
A
= 0.8V (see the Electrical Characteristics
= 0.8V, V
OUT_
(OUT_ to FB_ resistor) with the following
≥ 0.8V
R
A
R
A
=
can range from V
R
R
R
=
A
B
V
C
OUT_
R
BYPASS
⎡
⎢
⎢
⎣
B
V
⎡
⎢
⎢
⎣
V
BYPASS
⎛
⎜
⎝
FB
Setting the Output Voltage
V
MAX5098A
V
OUT
OUT_
_
FB
SOURCE_
−
= 2V (see the Electrical
BYPASS
_
V
_
OUT
−
FB_
can range from 0V to
⎞
⎟
⎠
V
V
OUT_
FB
−
1
FB_
C
_
⎤
⎥
⎥
⎦
_
< 0.8V
(FB_ to BYPASS
⎤
⎥
⎥
⎦
A
to 28V (boost
DROP2
with the fol-
R
R
C
A
V
OUT_
is the
B