MAX5092EVKIT+ Maxim Integrated Products, MAX5092EVKIT+ Datasheet - Page 12

• Manufacturer Part Number: MAX5092EVKIT+
• Description: KIT EVALUATION FOR MAX5092
• Manufacturer: Maxim Integrated Products

Specifications of MAX5092EVKIT+

• Main Purpose: DC/DC, Step Up with LDO
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 5V
• Current - Output: 250mA
• Voltage - Input: 4 ~ 72V
• Regulator Topology: Buck-Boost
• Board Type: Fully Populated
• Utilized Ic / Part: MAX5092B
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Frequency - Switching: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

4V to 72V Input LDOs with Boost Preregulator
The MAX5092A/MAX5092B/MAX5093A/MAX5093B
include a step-up, switch-mode DC-DC converter and a
linear regulator to provide step-up/-down voltage con-
version over a wide range of input voltages. This combi-
nation of an LDO and a boost converter offers the
advantage of using a single off-the-shelf inductor in
place of the multiple-winding custom magnetics needed
in typical SEPIC or transformer-based flyback topolo-
gies. The boost preregulator is completely turned off
during normal automotive operation (V
reduces quiescent current to 65µA (typ), and makes the
devices suitable for always-on power supplies.
The devices have an internal UVLO threshold of 3.8V
(max, V
device is enabled. When V
nal boost converter starts switching and regulates
V
low quiescent-current LDO steps down V
programmed LDO output voltage. The LDO output is
preset to 3.3V (MAX5092A/MAX5093A) or 5V
(MAX5092B/MAX5093B). Both output voltages can be
adjusted by using external resistor-dividers.
If (V
verter is disabled, forcing V
V
starts switching and regulates V
grammed voltage. The boost converter regulates
V
operation during low cold-crank voltages even if the pro-
grammed LDO output voltage is greater than V
less than 9V). The boost converter turn-on response time
is less than 10µs, making cold-crank input glitches trans-
parent to the system even at full load.
The boost-converter output is followed by a high PSRR,
low-quiescent-current LDO. The LDO rejects the
switching noise present at BSOUT and provides a
clean, regulated output voltage. The linear regulator
uses an internal p-channel MOSFET pass element.
Additional features include a power-on-reset function
with an externally adjustable timeout, an enable (EN)
input, and a hold (HOLD) regulator control input.
The switch-mode converter uses a minimum off-time,
maximum on-time pulse frequency modulation (PFM)
control scheme. The internal MOSFET turns on whenev-
er V
by V
12
BSOUT
BSOUT
BSOUT
BSOUT
BSOUT
______________________________________________________________________________________
BSFB
IN
- V
to the programmed boost output voltage. The
for V
- V
(see the Setting the Boost Output Voltage
rising) that must be exceeded before the
OUT
falls below the regulation point determined
OUT
IN
falls below 2V (typ), the boost converter
down to 3.5V, providing uninterrupted
) rises above 2.5V (typ), the boost con-
Detailed Description
IN
is above V
BSOUT
Boost Converter
BSOUT
to follow V
UVLO
BSOUT
to the pro-
IN
, the inter-
= 14V),
IN
to the
IN
(but
. If
(V
inductor current reaches the peak current limit (2.5A
typ) or after 2.25µs maximum on-time, whichever
occurs first. The MOSFET is held off for at least 1µs
after the turn-on phase. A new switching cycle initiates
once V
scheme, switching frequency and output ripple are
functions of load current and input voltage. No frequen-
cy compensation is needed in the PFM control scheme.
The output of the boost converter is preset to 7V and is
adjustable by using external resistors. See the Setting
the Boost Output Voltage V
If V
V
son is as V
boost converter is disabled, causing V
V
turns back on, and V
ripple, program V
old. See the Typical Operating Characteristics for the
Switching Waveforms.
Due to the integrated blocking diode in the MAX5092_,
V
boost output voltages (or to reduce the power dissipa-
tion in to the package). The MAX5093_ requires an
external diode for the boost converter. Select the exter-
nal diode according to the Schottky Diode Selection
(MAX5093_) section.
The MAX5092_/MAX5093_ contain an internal p-chan-
nel MOSFET used as the pass transistor for the LDO.
The output of the boost regulator is connected to the
source of the p-MOSFET. The LDO starts up 200µs
after the boost regulator starts up. The LDO supplies
up to 250mA with a typical dropout voltage of 0.9V. The
maximum LDO output current is determined by the
package power-dissipation limit as well as the internal
current limit. The LDO is designed to be a low-quies-
cent-current type. During normal operation when the
battery voltage is > 9V, the MAX5092_/MAX5093_ con-
sume only 75µA (max) at +85°C and 100µA load.
The output voltage of the LDO is set using the SET
input. Connect SET to SGND to use the factory-preset
output voltage. Connect SET to the center of an exter-
nal resistor-divider connected from OUT to SGND to
program a different output voltage. See the Setting the
LDO Output Voltage (V
BST_DIS
BSOUT
BSOUT
BSOUT
BSOUT
BSOUT
is limited to 11V. Use the MAX5093_ for higher
falls to V
), larger ripple is observed on BSOUT. The rea-
) section). The MOSFET turns off when the
BSOUT
is programmed greater than (V
falls below the threshold. In this control
BSOUT
OUT
rises above V
BSOUT
+ V
OUT
within the boost disable thresh-
BST_EN
BSOUT
) section.
rises. For the lowest V
, the boost converter
Linear Regulator
OUT
section.
BSOUT
+ V
BST_DIS
to fall. As
OUT
BSOUT
, the
+