19-4299; Rev 2; 6/09
KIT
ATION
EVALU
BLE
AVAILA
80V, 300mW Boost Converter and Current
Monitor for APD Bias Applications
General Description
The MAX15031 consists of a constant-frequency pulse-
width modulating (PWM) step-up DC-DC converter with
an internal switch and a high-side current monitor with
high-speed adjustable current limiting. This device can
generate output voltages up to 76V and provides current
monitoring up to 4mA (up to 300mW). The MAX15031
can be used for a wide variety of applications such as
avalanche photodiode biasing, PIN biasing, or varactor
biasing, and LCD displays. The MAX15031 operates
from 2.7V to 11V.
The constant-frequency (400kHz), current-mode PWM
architecture provides low-noise output voltage that is
easy to filter. A high-voltage, internal power switch
allows this device to boost output voltages up to 76V.
Internal soft-start circuitry limits the input current when
the boost converter starts. The MAX15031 features a
shutdown mode to save power.
The MAX15031 includes a current monitor with more
than three decades of dynamic range and monitors cur-
rent ranging from 500nA to 4mA with high accuracy.
Resistor-adjustable current limiting protects the APD
from optical power transients. A clamp diode protects
the monitor’s output from overvoltage conditions. Other
protection features include cycle-by-cycle current limit-
ing of the boost converter switch, undervoltage lockout,
and thermal shutdown if the die temperature reaches
+160°C.
The MAX15031 is available in a thermally enhanced
4mm x 4mm, 16-pin TQFN package and operates over
the -40°C to +125°C automotive temperature range.
Features
♦
Input Voltage Range
+2.7V to +5.5V (Using Internal Charge Pump) or
+5.5V to +11V
♦
Wide Output-Voltage Range from (V
IN
+ 1V) to 76V
♦
Internal 1Ω (typ) 80V Switch
♦
300mW Boost Converter Output Power
♦
Accurate ±10% (500nA to 1mA) and ±3.5% (1mA
to 4mA) High-Side Current Monitor
♦
Resistor-Adjustable Ultra-Fast APD Current Limit
(1µs Response Time)
♦
Open-Drain Current-Limit Indicator Flag
♦
400kHz Fixed Switching Frequency
♦
Constant PWM Frequency Provides Easy Filtering
in Low-Noise Applications
♦
Internal Soft-Start
♦
2µA (max) Shutdown Current
♦
-40°C to +125°C Temperature Range
♦
Small Thermally Enhanced, 4mm x 4mm, 16-Pin
TQFN Package
MAX15031
Ordering Information
PART
MAX15031ATE+
TEMP RANGE
-40°C to +125°C
PIN-PACKAGE
16 TQFN-EP*
+Denotes
a lead(Pb)-free/RoHS-compliant package.
*EP
= Exposed pad.
Applications
CLAMP
Pin Configuration
RLIM
9
APD
Avalanche Photodiode Biasing and Monitoring
PIN Diode Bias Supplies
Low-Noise Varactor Diode Bias Supplies
FBON Modules
GPON Modules
LCD Displays
TOP VIEW
12
11
MOUT
10
BIAS 13
SHDN 14
PGND 15
LX 16
8
7
ILIM
CNTRL
FB
SGND
MAX15031
6
*EP
+
1
PWR
2
CP
3
CN
5
Typical Operating Circuits appear at end of data sheet.
4
IN
*EXPOSED PAD
THIN QFN
(4mm
×
4mm)
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
80V, 300mW Boost Converter and Current
Monitor for APD Bias Applications
MAX15031
ABSOLUTE MAXIMUM RATINGS
PWR, IN to SGND ...................................................-0.3V to +12V
LX to PGND ............................................................-0.3V to +80V
BIAS, APD to SGND ...............................................-0.3V to +80V
SHDN
to SGND............................................-0.3V to (V
IN
+ 0.3V)
CLAMP to SGND ......................................-0.3V to (V
BIAS
+ 0.3V)
FB,
ILIM,
RLIM, CP, CN, CNTRL to SGND .............-0.3V to +12V
PGND to SGND .....................................................-0.3V to +0.3V
MOUT to SGND ....................................-0.3V to (V
CLAMP
+ 0.3V)
Continuous Power Dissipation
16-Pin TQFN (derate 25mW/°C above +70°C) ............2000mW
Thermal Resistance (Note 1)
θ
JA
....................................................................................40°C/W
θ
JC
......................................................................................6°C/W
Operating Temperature Range .........................-40°C to +125°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Note 1:
Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-
layer board. For detailed information on package thermal considerations, refer to
www.maxim-ic.com/thermal-tutorial.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(V
IN
= V
PWR
= 3.3V. V
SHDN
= 3.3V. C
IN
= C
PWR
= 10μF. C
CP
= 10nF, V
CNTRL
= V
IN
. V
RLIM
= 0. V
PGND
= V
SGND
= 0. V
BIAS
= 40V.
APD = unconnected. CLAMP = unconnected.
ILIM
= unconnected, MOUT = unconnected. T
A
= T
J
= -40°C to +125°C, unless other-
wise noted. Typical values are at T
A
= +25°C.) (Note 2)
PARAMETER
Supply Voltage Range
SYMBOL
V
IN
, V
PWR
CONDITIONS
CP connected to IN, C
CP
= open
V
FB
= 1.4V, no switching
Supply Current
Undervoltage Lockout Threshold
Undervoltage Lockout Hysteresis
Shutdown Current
BIAS Current During Shutdown
BOOST CONVERTER
Output-Voltage Adjustment
Range
Switching Frequency
Maximum Duty Cycle
FB Set-Point Voltage
FB Input Bias Current
f
SW
D
CLK
V
FB
I
FB
V
PWR
= V
IN
= 2.9V,
V
CP
= 5.5V
V
PWR
= V
IN
= 5.5V,
V
CP
= 10V
V
PWR
= V
IN
= V
CP
= 5.5V
V
PWR
= V
IN
= V
CP
= 11V
0.8
V
LX
= 36V
2.9V V
PWR
11V, V
PWR
= V
IN
,
I
LOAD
= 4.5mA
0
I
LOAD
4.5mA
0.2
1
1
1
1
1
1.2
V
IN
= V
PWR
= 5V
2.9V
2.9V
V
PWR
V
PWR
11V, V
IN
= V
PWR
11V, V
IN
= V
PWR
V
IN
+
1V
360
352
86
1.2201
400
400
90
1.245
76
440
448
94
1.2699
100
2
2
2
2
1.6
1
A
μA
%
%
V
kHz
%
V
nA
I
SUPPLY
V
UVLO
V
UVLO_HYS
SHDN
pulled low
I
BIAS_SHDN
V
BIAS
= 3.3V, V
SHDN
= 0
I
IN_SHDN
V
IN
= 11V, V
FB
= 1.4V (no switching),
C
CP
= open, CP = IN
V
IN
rising
2.375
MIN
2.7
5.5
1
1.2
2.5
100
2
30
TYP
MAX
5.5
11
2
3
2.675
mA
V
mV
μA
μA
UNITS
V
I
LX
= 100mA
Internal Switch On-Resistance
R
ON
I
LX
= 100mA,
V
CP
= V
IN
Peak Switch Current Limit
LX Leakage Current
Line Regulation
Load Regulation
I
LIM_LX
2
_______________________________________________________________________________________
80V, 300mW Boost Converter and Current
Monitor for APD Bias Applications
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= V
PWR
= 3.3V. V
SHDN
= 3.3V. C
IN
= C
PWR
= 10μF. C
CP
= 10nF, V
CNTRL
= V
IN
. V
RLIM
= 0. V
PGND
= V
SGND
= 0. V
BIAS
= 40V.
APD = unconnected. CLAMP = unconnected.
ILIM
= unconnected, MOUT = unconnected. T
A
= T
J
= -40°C to +125°C, unless other-
wise noted. Typical values are at T
A
= +25°C.) (Note 2)
PARAMETER
Soft-Start Duration
Soft-Start Steps
CONTROL INPUT (CNTRL)
Maximum Control Input Voltage
Range
CURRENT MONITOR
Bias Voltage Range
Bias Quiescent Current
Voltage Drop
Dynamic Output Resistance at
MOUT
MOUT Output Leakage
Output Clamp Voltage
Output Clamp Leakage Current
Output-Voltage Range
Current Gain
V
MOUT
I
MOUT
/I
APD
V
MOUT
-
V
CLAMP
V
BIAS
I
BIAS
V
DROP
R
MOUT
I
APD
= 500nA
I
APD
= 2mA
I
APD
= 2mA, V
DROP
= V
BIAS
- V
APD
I
APD
= 500nA
I
APD
= 2.5mA
APD is unconnected
Forward diode current = 1mA
V
BIAS
= V
CLAMP
= 76V
10V V
BIAS
76V, 0 I
APD
CLAMP is unconnected
I
APD
= 500nA
I
APD
= 2mA
( I
MOUT
/I
MOUT
)/ V
BIAS
,
V
BIAS
= 10V to 76V
V
APD
= 35V, R
LIM
= 3.3k
12.45k
R
LIM
2.5k
I
MOUT
settles to within
0.1%, 10nF connected
from APD to ground
I
APD
= 500nA
I
APD
= 2.5mA
I
APD
= 500nA
I
APD
= 5μA to
1mA
1mA,
V
BIAS
-
1V
0.095
0.0965
-1000
-250
3.15
1
7.5
90
0.1
0.1
+300
+24
3.75
0.11
0.1035
+1500
ppm/V
+250
4.35
5
mA
mA
ms
μs
0.5
1
890
1
0.73
1
0.95
10
76
100
3.2
1
V
μA
mA
V
G
M
nA
V
nA
V
FB set point is regulated to V
CNTRL
1.25
V
(0.25 x I
LIM_LX
) to I
LIM_LX
SYMBOL
CONDITIONS
MIN
TYP
8
32
MAX
UNITS
ms
Steps
MAX15031
Power-Supply Rejection Ratio
(Note 3)
APD Input Current Limit
Current-Limit Adjustment Range
Power-Up Settling Time
LOGIC INPUTS/OUTPUTS
SHDN
Input-Voltage Low
SHDN
Input-Voltage High
ILIM
Output-Voltage Low
ILIM
Output Leakage Current
THERMAL PROTECTION
Thermal Shutdown
Thermal Shutdown Hysteresis
PSRR
I
LIM_APD
t
S
V
IL
V
IH
V
OL
I
OH
I
LIM
= 2mA
V
ILIM
= 11V
Temperature rising
+160
10
2.4
0.8
0.3
1
V
V
V
μA
°C
°C
Note 2:
All minimum/maximum parameters are tested at T
A
= +125°C. Limits over temperature are guaranteed by design.
Note 3:
Guaranteed by design and not production tested.
_______________________________________________________________________________________
3
80V, 300mW Boost Converter and Current
Monitor for APD Bias Applications
MAX15031
Typical Operating Characteristics
(V
PWR
= V
IN
= 3.3V, V
OUT
= 70V, circuit of Figure 3 (Figure 4 for V
IN
> 5.5V), unless otherwise noted.)
EFFICIENCY vs. LOAD CURRENT
MAX15031 toc01
EFFICIENCY vs. LOAD CURRENT
V
OUT
= 30V
MAX15031 toc02
EFFICIENCY vs. LOAD CURRENT
MAX15031 toc03
70
60
50
EFFICIENCY (%)
V
OUT
= 30V
70
60
50
EFFICIENCY (%)
70
60
50
EFFICIENCY (%)
40
30
20
10
V
IN
= 3.3V
V
IN
= 5V
V
IN
= 8V
40
30
20
10
V
IN
= 3.3V
0
0
1
2
LOAD CURRENT (mA)
3
4
V
OUT
= 70V
V
OUT
= 55V
40
30
V
OUT
= 70V
20
10
V
IN
= 5V
0
0
1
2
LOAD CURRENT (mA)
3
4
V
OUT
= 55V
V
OUT
= 70V
0
0
1
2
LOAD CURRENT (mA)
3
4
MINIMUM STARTUP VOLTAGE
vs. LOAD CURRENT
MAX15031 toc04
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
1.8
1.6
SUPPLY CURRENT (mA)
1.4
1.2
1.0
0.8
0.6
0.4
T
A
= +125°C
T
A
= +85°C
T
A
= -40°C
T
A
= +25°C
MAX15031 toc05
NO-LOAD SUPPLY CURRENT
vs. SUPPLY VOLTAGE
XMAX15031 toc06
2.55
MINIMUM STARTUP VOLTAGE (V)
2.54
2.53
2.52
2.51
2.50
2.49
2.48
0
1
2
LOAD CURRENT (mA)
3
4
2.0
60
NO-LOAD SUPPLY CURRENT (mA)
50
T
A
= +85°C
40
T
A
= +25°C
30
T
A
= -40°C
20
10
0
3
4
5
6
7
8
9
10
0.2
0
0
1
2
3
4
5
6
7
8
SUPPLY VOLTAGE (V)
V
FB
= 1.4V
9 10 11
11
SUPPLY VOLTAGE (V)
EXITING SHUTDOWN
MAX15031 toc07
ENTERING SHUTDOWN
MAX15031 toc08
V
OUT
50V/div
3V
70V
OUTPUT VOLTAGE
50V/div
3V
INDUCTOR CURRENT
500mA/div
0mA
I
L
500mA/div
0mA
0V
1ms/div
I
OUT
= 1mA
V
SHDN
2V/div
I
LOAD
= 1mA
4ms/div
SHUTDOWN VOLTAGE
2V/div
0V
4
_______________________________________________________________________________________
80V, 300mW Boost Converter and Current
Monitor for APD Bias Applications
Typical Operating Characteristics (continued)
(V
PWR
= V
IN
= 3.3V, V
OUT
= 70V, circuit of Figure 3 (Figure 4 for V
IN
> 5.5V), unless otherwise noted.)
MAX15031
LIGHT-LOAD SWITCHING
WAVEFORM WITH RC FILTER
MAX15031 toc09
HEAVY-LOAD SWITCHING
WAVEFORM WITH RC FILTER
MAX15031 toc10
I
OUT
= 0.1mA, V
BIAS
= 70V
V
BIAS
AC-COUPLED
1mV/div
V
LX
50V/div
0V
I
L
500mA/div
0mA
I
OUT
= 4mA, V
BIAS
= 70V
V
BIAS
AC-COUPLED
1mV/div
V
LX
50V/div
0V
I
L
500mA/div
0mA
1μs/div
1μs/div
LOAD-TRANSIENT RESPONSE
MAX15031 toc11
LINE-TRANSIENT RESPONSE
MAX15031 toc12
LX LEAKAGE CURRENT
vs. TEMPERATURE
V
IN
2V/div
3.3V
180
LX LEAKAGE CURRENT (nA)
160
140
120
100
80
60
40
20
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
CURRENT INTO
LX PIN
MAX15031 toc13
200
V
OUT
AC-COUPLED
200mV/div
I
LOAD
5mA/div
0mA
V
OUT
= 70V
V
IN
= 3.3V
100ms/div
100ms/div
V
OUT
= 70V
I
OUT
= 1mA
t
RISE
= 50μs
V
OUT
AC-COUPLED
100mV/div
LOAD REGULATION
MAX15031 toc14
MAXIMUM LOAD CURRENT
vs. INPUT VOLTAGE
MAX15031 toc15
BIAS CURRENT
vs. BIAS VOLTAGE
MAX15031 toc16
70.0
69.8
69.6
OUTPUT VOLTAGE (V)
69.4
69.2
69.0
68.8
68.6
68.4
68.2
68.0
0
1
2
3
4
5
LOAD CURRENT (mA)
110
100
MAXIMUM LOAD CURRENT (mA)
90
80
70
60
50
40
30
20
10
0
3
E
F
A: V
OUT
= 30V, B: V
OUT
= 35V, C: V
OUT
= 45V,
D: V
OUT
= 55V, E: V
OUT
= 60V, F: V
OUT
= 72V
4
5
6
7
8
9
10
A
B
C
D
10
BIAS CURRENT (mA)
1
I
APD
= 2mA
0.1
I
APD
= 500nA
0.01
0
10
20
30
40
50
60
70
80
BIAS VOLTAGE (V)
11
INPUT VOLTAGE (V)
_______________________________________________________________________________________
5
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