MAX15035ETL+ Maxim Integrated Products, MAX15035ETL+ Datasheet - Page 16

• Manufacturer Part Number: MAX15035ETL+
• Description: IC REG STEP DOWN 15A 40-TQFN
• Manufacturer: Maxim Integrated Products
• Type: Step-Down (Buck)r

Specifications of MAX15035ETL+

• Internal Switch(s): Yes
• Synchronous Rectifier: Yes
• Number Of Outputs: 1
• Voltage - Output: 1.05V, 1.5V
• Current - Output: 15A
• Voltage - Input: 4.5 ~ 26 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 40-TQFN Exposed Pad
• Power - Output: 2.16W
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Frequency - Switching: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

15A Step-Down Regulator with Internal Switches
When the on-time expires, the controller re-enables the
low-side MOSFET until the controller detects that the
inductor current drops below the zero-crossing thresh-
old. Starting with a negative inductor current pulse
greatly reduces the peak output voltage when com-
pared to starting with a positive inductor current pulse.
The output voltage at the beginning of the ultrasonic
pulse determines the negative ultrasonic current
threshold, resulting in the following equation:
where V
The low-noise, forced-PWM mode (SKIP = V
ables the zero-crossing comparator, which controls the
low-side switch on-time. This forces the low-side gate-
drive waveform to constantly be the complement of the
high-side gate-drive waveform, so the inductor current
reverses at light loads while LX maintains a duty factor
of V
keep the switching frequency fairly constant. However,
forced-PWM operation comes at a cost: the no-load 5V
bias current remains between 10mA to 50mA, depend-
ing on the switching frequency.
The MAX15035 automatically always uses forced-PWM
operation during shutdown, regardless of the SKIP
configuration.
Figure 4. Dynamic Transition when SKIP = GND
16
OUT
______________________________________________________________________________________
V
FB
/V
ISONIC
IN
> V
INTERNAL
PWM CONTROL
DYNAMIC TRANSITION WHEN SKIP# = GND
. The benefit of forced-PWM mode is to
REFIN
=
PGOOD
I
OUTPUT
VOLTAGE
L
OVP
REFIN
LX
×
.
Forced-PWM Mode ( S S K K I I P P = V
0 006
.
=
(
V
REFIN
−
V
FB
)
×
0 7
INTERNAL TARGET
SET TO REF + 300mV
.
DD
NO PULSES: V
BLANK HIGH-Z
) dis-
DD
SKIP
)
ACTUAL V
OUT
> V
TARGET
In skip mode (SKIP = GND or 3.3V), an inherent auto-
matic switchover to PFM takes place at light loads. This
switchover is affected by a comparator that truncates
the low-side switch on-time at the inductor current’s
zero crossing. The zero-crossing comparator threshold
is set by the differential across LX to GND.
DC output-accuracy specifications refer to the threshold
of the error comparator. When the inductor is in continu-
ous conduction, the MAX15035 regulates the valley of
the output ripple, so the actual DC output voltage is
higher than the trip level by 50% of the output ripple
voltage. In discontinuous conduction (SKIP = GND and
I
lation level higher than the error-comparator threshold
by approximately 1.5% due to slope compensation.
When SKIP is pulled to GND, the MAX15035 remains in
pulse-skipping mode. Since the output is not able to
sink current, the timing for negative dynamic output-volt-
age transitions depends on the load current and output
capacitance. Letting the output voltage drift down is
typically recommended to reduce the potential for audi-
ble noise since this eliminates the input current surge
during negative output-voltage transitions. See Figures
4 and 5.
OUT
Automatic Pulse-Skipping Mode ( S S K K I I P P = GND or REF)
OUT
< I
LOAD(SKIP)
BLANK HIGH-Z
), the output voltage has a DC regu-
DYNAMIC REFIN WINDOW
EA TARGET + 300mV