MAX15031ATE+T Maxim Integrated Products, MAX15031ATE+T Datasheet - Page 10

• Manufacturer Part Number: MAX15031ATE+T
• Description: IC BOOST CONV/CURRENT MON 16TQFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX15031ATE+T

• Applications: Converter Current Monitor, APD Bias Applications
• Voltage - Input: 2.7 ~ 11 V
• Number Of Outputs: 1
• Voltage - Output: 3.7 ~ 76 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 16-TQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

80V, 300mW Boost Converter and Current
Monitor for APD Bias Applications
The MAX15031 constant-frequency, current-mode, PWM
boost converter is intended for low-voltage systems that
require a locally generated high voltage. This device can
generate a low-noise, high output voltage required for
PIN and varactor diode biasing and LCD displays. The
MAX15031 operates either from +2.7V to +5.5V or from
+5.5V to +11V. For 2.7V to 5.5V operation, an internal
charge pump with an external 10nF ceramic capacitor is
used. For 5.5V to 11V operation, connect CP to IN and
leave CN unconnected.
The MAX15031 operates in discontinuous mode in
order to reduce the switching noise caused by reverse-
voltage recovery charge of the rectifier diode. Other
continuous mode boost converters generate large volt-
age spikes at the output when the LX switch turns on
10
CNTRL
______________________________________________________________________________________
SGND
CN
CP
FB
IN
V
REF
V
(DOUBLER)
REF
CHARGE
PUMP
UVLO
Detailed Description
MUX
REFERENCE
COMPARATOR
-A
+A
-C
+C
MAX15031
OUTPUT ERROR AND CURRENT
COMPARATOR
OSCILLATOR
400kHz
CLK
SHDN
SOFT-
START
SHUTDOWN
REFERENCE
THERMAL
BIAS AND
V
REF
PEAK CURRENT-LIMIT
COMPARATOR
because there is a conduction path between the out-
put, diode, and switch to ground during the time need-
ed for the diode to turn off and reverse its bias voltage.
To reduce the output noise even further, the LX switch
turns off by taking 10ns typically to transition from ON
to OFF. As a consequence, the positive slew rate of the
LX node is reduced and the current from the inductor
does not “force” the output voltage as hard as would
be the case if the LX switch were to turn off faster.
The constant-frequency (400kHz) PWM architecture
generates an output voltage ripple that is easy to filter.
An 80V vertical DMOS device used as the internal
power switch is ideal for boost converters with output
voltages up to 76V. The MAX15031 can also be used in
other topologies where the PWM switch is grounded,
like SEPIC and flyback converters.
CONTROL
CURRENT
MONITOR
SWITCH
LOGIC
PWR
BIAS
1x
10x
Functional Diagram
80V
DMOS
ADJUSTMENT
CURRENT-
CURRENT
CURRENT
SWITCH
SENSE
LIMIT
LIMIT
LX
PGND
CLAMP
MOUT
RLIM
APD
ILIM