General Description
The MAX5075 is a +4.5V to +15V push-pull, current-fed
topology driver subsystem with an integrated oscillator
for use in telecom module power supplies. The device
drives two MOSFETs connected to a center-tapped
transformer primary providing secondary-side, isolated,
negative or positive voltages. This device features a pro-
grammable, accurate, integrated oscillator with a syn-
chronizing clock output that synchronizes an external
PWM regulator. A single external resistor programs the
internal oscillator frequency from 50kHz to 1.5MHz.
The MAX5075 incorporates a dual MOSFET driver with
±3A peak drive currents and 50% duty cycle. The
MOSFET driver generates complementary signals to
drive external ground-referenced n-channel MOSFETs.
The MAX5075 is available with a clock output frequency
to MOSFET driver frequency ratio of 1x, 2x, and 4x. The
MAX5075 is available in a thermally enhanced 8-pin
µMAX®package and is specified over the -40°C to
+125°C operating temperature range.
Applications
Current-Fed, High-Efficiency Power-Supply Modules
Power-Supply Building Subsystems
Push-Pull Driver Subsystems
Features
♦Current-Fed, Push-Pull Driver Subsystem
♦Programmable, Accurate Internal Oscillator
♦Single +4.5V to +15V Supply Voltage Range
♦Dual ±3A Gate-Drive Outputs
♦1mA Operating Current at 250kHz with No
Capacitive Load
♦Synchronizing Clock Frequency Generation
Options
♦ Thermally Enhanced 8-Pin µMAX Package
♦-40°C to +125°C Operating Temperature Range
MAX5075
Push-Pull FET Driver with Integrated Oscillator
and Clock Output
________________________________________________________________ Maxim Integrated Products 1
Ordering Information
19-3662; Rev 1; 5/07
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Pin Configuration appears at end of data sheet.
PART PIN-
PACKAGE
TOP
MARK
PKG
CODE
fCLK/fNDRV_
RATIO
MAX5075AAUA
8 µMAX-EP* AAAU U8E-2
1
MAX5075BAUA
8 µMAX-EP* AAAV U8E-2
2
MAX5075CAUA
8 µMAX-EP* AAAW U8E-2
4
*EP = Exposed paddle.
Note: All devices specified for -40°C to +125°C operating
temperature range.
MAX5075
1nF
4.7kΩ
NDRV2
DRVH
DRVL
GND
GND
VIN
VIN
PWM
CONTROLLER
SYNCIN
NDRV1
VCC
RT
PGNDI.C.
CLK
VCC
VOUT
Typical Operating Circuit
µMAX is a registered trademark of Maxim Integrated Products, Inc.
MAX5075
Push-Pull FET Driver with Integrated Oscillator
and Clock Output
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VCC = +12V, RRT = 124kΩ, NDRV1 = NDRV2 = open, TA= TJ= -40°C to +125°C, unless otherwise noted. Typical values are measured
at TA= +25°C.) (Note 1)
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.
VCC to DGND, PGND .............................................-0.3V to +18V
CLK, RT to DGND.....................................................-0.3V to +6V
NDRV1, NDRV2 to PGND...........................-0.3V to (VCC + 0.3V)
DGND to PGND.....................................................-0.3V to +0.3V
CLK Current......................................................................±20mA
NDRV1, NDRV2 Peak Current (200ns) ..................................±5A
NDRV1, NDRV2 Reverse Current (Latchup Current)......±500mA
Continuous Power Dissipation (TA= +70°C)
8-Pin µMAX (derate 10.3mW/°C above +70°C) ...........825mW
Operating Temperature Range .........................-40°C to +125°C
Maximum Junction Temperature .....................................+150°C
Storage Temperature Range .............................-60°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
PARAMETER
SYMBOL
CONDITIONS
MIN TYP MAX
UNITS
SUPPLY
Input Voltage Supply Range VCC 4.5
15.0
V
Switching Supply Current ICCSW fOSC = 250kHz 1 3 mA
Undervoltage Lockout VUVLO VCC rising 3 3.5 4 V
UVLO Hysteresis
300
mV
OSCILLATOR
Frequency Range fOSC (Note 2) 50
1500
kHz
Accuracy fOSC = 250kHz , 6V ≤ VCC ≤ 15V (Note 3) -8 +10 %
Oscillator Jitter
±0.6
%
7V ≤ VCC ≤ 15V 3.9 5.0
CLK Output High Voltage ICLK = 1mA 4.5V ≤ VCC ≤ 7V
3.35
5.0 V
CLK Output Low Voltage ICLK = -1mA 50 mV
CLK Output Rise Time CCLK = 30pF 35 ns
CLK Output Fall Time CCLK = 30pF 10 ns
GATE DRIVERS (NDRV1, NDRV2)
Output High Voltage VOH INDRV1 = INDRV2 = 100mA VCC -
0.3 V
Output Low Voltage VOL INDRV1 = INDRV2 = -100mA 0.3 V
Output Peak Current IPSourcing and sinking 3 A
NDRV_ sourcing 100mA 1.8 3
Driver Output Impedance NDRV_ sinking 100mA 1.6 2.6 Ω
Latchup Current Protection Reverse current at NDRV1/NDRV2
400
mA
Rise Time tRCLOAD = 2nF 10 ns
Fall Time tFCLOAD = 2nF 10 ns
Note 1: The MAX5075 is 100% tested at TA= TJ= +125°C. All limits over temperature are guaranteed by design.
Note 2: Use the following formula to calculate the MAX5075 oscillator frequency: fOSC = 1012/(32 x RRT).
Note 3: The accuracy of the oscillator’s frequency is lower at frequencies greater than 1MHz.
MAX5075
Push-Pull FET Driver with Integrated Oscillator
and Clock Output
_______________________________________________________________________________________ 3
Typical Operating Characteristics
(VCC = +12V, RRT = 124kΩ, NDRV_ = open, CLK = open.)
2
4
6
8
10
12
14
0
CLK FALL TIME
vs. SUPPLY VOLTAGE
MAX5075 toc06
SUPPLY VOLTAGE (V)
CLK FALL TIME (ns)
141311 126789105415
CCLK = 30pF
MAX5075
Push-Pull FET Driver with Integrated Oscillator
and Clock Output
4 _______________________________________________________________________________________
Typical Operating Characteristics (continued)
(VCC = +12V, RRT = 124kΩ, NDRV_ = open, CLK = open.)
MAX5075
Push-Pull FET Driver with Integrated Oscillator
and Clock Output
_______________________________________________________________________________________ 5
Pin Description
PIN NAME FUNCTION
1 CLK
Synchronizing Clock Output. Clock output with a ±10mA peak current drive that can be used to
synchronize an external PWM regulator. CLK/NDRV1 frequency has a 1x, 2x, or 4x ratio. See the
Synchronizing Clock Output section.
2 I.C. Internal Connection. Connect to ground. Internal function.
3RT
Oscillator Timing Resistor Connection. Bypass RT with a series combination of a 4.7kΩ resistor and a
1nF capacitor to DGND. Connect a resistor from RT to DGND to set the internal oscillator.
4 DGND Digital Ground. Connect DGND to ground plane.
5 PGND Power Ground. Connect PGND to ground plane.
6 NDRV1 Gate Driver 1. Connect NDRV1 to the gate of the external n-channel FET.
7 NDRV2 Gate Driver 2. Connect NDRV2 to the gate of the external n-channel FET.
8V
CC Power-Supply Input. Bypass VCC to PGND with 0.1µF||1µF ceramic capacitors.
EP EP Exposed Pad. Internally connected to DGND. Connect exposed pad to ground plane.
NDRV1
PGND
VCC
NDRV2
T-FF
UVLO 3.5V
Q
Q
CLK
RT
DGND
OSC
I.C.
5V
LDO
VCC
A (1x)
B (2x)
C (4x)
MAX5075
Q
Q
Q
Q
INTERNAL
FUNCTION
Figure 1. MAX5075 Functional Diagram
MAX5075
Detailed Description
The MAX5075 is a +4.5V to +15V push-pull, current-fed
topology driver subsystem with an integrated oscillator
for use in 48V module power supplies.
The MAX5075 features a programmable, accurate inte-
grated oscillator with a synchronizing clock output that
can be used to synchronize an external PWM stage. A
single external resistor programs the internal oscillator
frequency from 50kHz to 1.5MHz.
The MAX5075 incorporates a dual MOSFET driver with
±3A peak drive currents and a 50% duty cycle. The
MOSFET driver generates complementary signals to
drive external ground-referenced n-channel MOSFETs.
The MAX5075 is available with a clock output frequency
to MOSFET driver frequency ratios of 1x , 2x, and 4x.
Internal Oscillator
An external resistor at RT programs the MAX5075
internal oscillator frequency from 50kHz to 1.5MHz. The
MAX5075A/B NDRV1 and NDRV2 switching frequen-
cies are one-half the programmed oscillator frequency
with a nominal 50% duty cycle. The MAX5075C NDRV1
and NDRV2 switching frequencies are one-fourth the
oscillator frequency.
Use the following formula to calculate the internal oscil-
lator frequency:
where fOSC is the oscillator frequency and RRT is a
resistor connected from RT to DGND in ohms.
Place a series combination of a 4.7kΩresistor and a
1nF capacitor from RT to DGND for stability and to filter
out noise.
Synchronizing Clock Output
The MAX5075 provides a buffered clock output that can
be used to synchronize the oscillator input of a PWM con-
troller. CLK is powered from an internal 5V regulator and
sources/sinks up to 10mA. The MAX5075 has internal
CLK output frequency to NDRV1 and NDRV2 switching
frequency ratios set to 1x, 2x, or 4x (Table 1).
The MAX5075A has a CLK frequency to NDRV_ frequen-
cy ratio set to 1x. The MAX5075B has a CLK frequency to
NDRV_ frequency ratio set to 2x and the MAX5075C has
a CLK frequency to NDRV_ frequency ratio set to 4x.
There is a typical 30ns delay from CLK to NDRV_ output.
Applications Information
Supply Bypassing
Pay careful attention to bypassing and grounding the
MAX5075. Peak supply and output currents may exceed
3A when driving large MOSFETs. Ground shifts due to
insufficient device grounding may also disturb other cir-
cuits sharing the same ground-return path. Any series
inductance in the VCC, NDRV1, NDRV2, and/or GND
paths can cause noise due to the very high di/dt when
switching the MAX5075 with any capacitive load. Place
one or more 0.1µF ceramic capacitors in parallel as close
to the device as possible to bypass VCC to PGND. Use a
ground plane to minimize ground-return resistance and
inductance. Place the external MOSFETs as close as
possible to the MAX5075 to further minimize board induc-
tance and AC path impedance.
fxR
OSC RT
=10
32
12
Push-Pull FET Driver with Integrated Oscillator
and Clock Output
6 _______________________________________________________________________________________
PART fCLK fNDRV1 fCLK to fSW
RATIO
MAX5075A fOSC / 2 fOSC / 2 1
MAX5075B fOSC fOSC / 2 2
MAX5075C fOSC fOSC / 4 4
Table 1. MAX5075 CLK Output Frequency
CLK
OSC
NDRV1
NDRV2
CLK
OSC
NDRV1
NDRV2
CLK
OSC
NDRV1
NDRV2
MAX5075A
MAX5075B
MAX5075C
Figure 2. MAX5075 CLK Timing Diagrams
Power Dissipation
The power dissipation of the MAX5075 is a function of
the sum of the quiescent current and the output current
(either capacitive or resistive load). Maintain the sum of
the currents so the maximum power dissipation limit is
not exceeded. The power dissipation (PDISS) due to the
quiescent switching supply current (ICCSW) can be cal-
culated as:
PDISS = VCC x ICCSW
For capacitive loads, use the following equation to esti-
mate the power dissipation:
PLOAD = 2 x CLOAD x VCC2 x fNDRV_
where CLOAD is the capacitive load at NDRV1 and
NDRV2, VCC is the supply voltage, and fNDRV_ is the
MAX5075 NDRV_ switching frequency.
Calculate the total power dissipation (PT) as follows:
PT = PDISS + PLOAD
Layout Recommendations
The MAX5075 sources and sinks large currents that can
create very fast rise and fall edges at the gate of the
switching MOSFETs. The high di/dt can cause unaccept-
able ringing if the trace lengths and impedances are not
well controlled. Use the following PC board layout guide-
lines when designing with the MAX5075:
• Place one or more 0.1µF decoupling ceramic
capacitors from VCC to PGND as close to the
device as possible. Connect VCC and all ground
pins to large copper areas. Place one bulk capaci-
tor of 10µF on the PC board with a low-impedance
path to the VCC input and PGND of the MAX5075.
• Two AC current loops form between the device and
the gate of the driven MOSFETs. The MOSFETs
look like a large capacitance from gate to source
when the gate pulls low. The current loop is from
the MOSFET gate to NDRV1 and NDRV2 of the
MAX5075, to PGND, and to the source of the
MOSFET. When the gate of the MOSFET pulls high,
the current is from the VCC terminal of the decou-
pling capacitor, to VCC of the MAX5075, to NDRV1
and NDRV2, and to the MOSFET gate and source.
Both charging current and discharging current loops
are important. Minimize the physical distance and
the impedance in these AC current paths.
• Keep the device as close to the MOSFET as possible.
Chip Information
TRANSISTOR COUNT: 1335
PROCESS: BiCMOS
MAX5075
Push-Pull FET Driver with Integrated Oscillator
and Clock Output
_______________________________________________________________________________________ 7
1
2
3
4
8
7
6
5
VCC
NDRV2
NDRV1
PGNDDGND
RT
I.C.
CLK *EP
*EXPOSED PADDLE CONNECTED TO DGND.
MAX5075
µMAX
TOP VIEW
Pin Configuration
MAX5075
Push-Pull FET Driver with Integrated Oscillator
and Clock Output
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
8_____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages.)
8L, µMAX, EXP PAD.EPS
C11
21-0107
Revision History
Pages changed at Rev 1: 1, 2, 5, 6, 8