19-3662; Rev 0; 5/05
Push-Pull FET Driver with Integrated Oscillator
and Clock Output
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.
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
Ordering Information
PART
PIN-
PACKAGE
TOP
MARK
AAAU
AAAV
PKG
CODE
U8E-2
U8E-2
U8E-2
f
CLK
/f
NDRV_
RATIO
1
2
4
Applications
Current-Fed, High-Efficiency Power-Supply Modules
Power-Supply Building Subsystems
Push-Pull Driver Subsystems
µMAX is a registered trademark of Maxim Integrated Products, Inc.
Pin Configuration appears at end of data sheet.
MAX5075AAUA 8 µMAX-EP*
MAX5075BAUA 8 µMAX-EP*
MAX5075CAUA 8 µMAX-EP* AAAW
*EP
= Exposed paddle.
Note:
All devices specified for -40°C to +125°C operating
temperature range.
Typical Operating Circuit
V
IN
V
IN
V
OUT
DRVH
PWM
CONTROLLER
V
CC
V
CC
NDRV2
SYNCIN
CLK
MAX5075
RT
NDRV1
DRVL
GND
DGND
I.C.
PGND
GND
________________________________________________________________
Maxim Integrated Products
1
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.
Push-Pull FET Driver with Integrated Oscillator
and Clock Output
MAX5075
ABSOLUTE MAXIMUM RATINGS
V
CC
to DGND, PGND .............................................-0.3V to +18V
CLK, RT to DGND.....................................................-0.3V to +6V
NDRV1, NDRV2 to PGND...........................-0.3V to (V
CC
+ 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 (T
A
= +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
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
CC
= +12V, R
RT
= 124kΩ, NDRV1 = NDRV2 = open, T
A
= T
J
= -40°C to +125°C, unless otherwise noted. Typical values are measured
at T
A
= +25°C.)
(Note 1)
PARAMETER
SUPPLY
Input Voltage Supply Range
Switching Supply Current
Undervoltage Lockout
UVLO Hysteresis
OSCILLATOR
Frequency Range
Accuracy
Oscillator Jitter
CLK Output High Voltage
CLK Output Low Voltage
CLK Output Rise Time
CLK Output Fall Time
GATE DRIVERS (NDRV1, NDRV2)
Output High Voltage
Output Low Voltage
Output Peak Current
Driver Output Impedance
Latchup Current Protection
Rise Time
Fall Time
t
R
t
F
V
OH
V
OL
I
P
I
NDRV1
= I
NDRV2
= 100mA
I
NDRV1
= I
NDRV2
= -100mA
Sourcing and sinking
NDRV_ sourcing 100mA
NDRV_ sinking 100mA
Reverse current at NDRV1/NDRV2
C
LOAD
= 2nF
C
LOAD
= 2nF
3
1.8
1.6
400
10
10
3
2.6
V
CC
-
0.3
0.3
V
V
A
Ω
mA
ns
ns
I
CLK
= 1mA
I
CLK
= -1mA
C
CLK
= 30pF
C
CLK
= 30pF
35
10
7V
≤
V
CC
≤
15V
4.5V
≤
V
CC
≤
7V
4.1
3.5
f
OSC
(Note 2)
f
OSC
= 250kHz , 6V
≤
V
CC
≤
15V (Note 3)
50
-8
±0.6
5.0
5.0
50
1500
+10
kHz
%
%
V
mV
ns
ns
V
CC
I
CCSW
V
UVLO
f
OSC
= 250kHz
V
CC
rising
3
4.5
1
3.5
300
15.0
3
4
V
mA
V
mV
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Note 1:
The MAX5075 is 100% tested at T
A
= T
J
= +125°C. All limits over temperature are guaranteed by design.
Note 2:
Use the following formula to calculate the MAX5075 oscillator frequency: f
OSC
= 10
12
/(32 x R
RT
).
Note 3:
The accuracy of the oscillator’s frequency is lower at frequencies greater than 1MHz.
2
_______________________________________________________________________________________
Push-Pull FET Driver with Integrated Oscillator
and Clock Output
MAX5075
Typical Operating Characteristics
(V
CC
= +12V, R
RT
= 124kΩ, NDRV_ = open, CLK = open.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX5075 toc01
SUPPLY CURRENT
vs. C
CLK
MAX5075 toc02
SUPPLY CURRENT
vs. TEMPERATURE
1.18
1.16
SUPPLY CURRENT (mA)
1.14
1.12
1.10
1.08
1.06
1.04
1.02
1.00
f
OSC
= 250kHz
MAX5075 toc03
7
6
SUPPLY CURRENT (mA)
5
4
3
2
1
0
4
5
6
7
8
f
OSC
= 500kHz
f
OSC
= 250kHz
f
OSC
= 100kHz
f
OSC
= 50kHz
f
OSC
= 1.25MHz
1.50
1.45
1.40
SUPPLY CURRENT (mA)
1.35
1.30
1.25
1.20
1.15
1.10
1.05
1.00
R
RT
= 124kΩ
1.20
9 10 11 12 13 14 15
0
20
40
60
80
100
-50
-25
0
25
50
75
100
125
SUPPLY VOLTAGE (V)
C
CLK
(pF)
TEMPERATURE (°C)
CLK RISE TIME
vs. SUPPLY VOLTAGE
MAX5075 toc04
CLK RISE TIME
vs. TEMPERATURE
MAX5075 toc05
CLK FALL TIME
vs. SUPPLY VOLTAGE
C
CLK
= 30pF
MAX5075 toc06
50
45
40
CLK RISE TIME (ns)
35
30
25
20
15
10
5
0
4
5
6
7
8
C
CLK
= 30pF
39.5
C
CLK
= 30pF
39.0
CLK RISE TIME (ns)
38.5
38.0
37.5
37.0
36.5
14
12
CLK FALL TIME (ns)
10
8
6
4
2
0
9 10 11 12 13 14 15
-50
-25
0
25
50
75
100
125
4
5
6
7
8
9 10 11 12 13 14 15
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
CLK FALL TIME
vs. TEMPERATURE
MAX5075 toc07
OSCILLATOR FREQUENCY
vs. SUPPLY VOLTAGE
R
RT
= 124kΩ
OSCILLATOR FREQUENCY (kHz)
254
252
250
248
246
T
A
= +125°C
244
242
T
A
= +25°C
T
A
= -40°C
MAX5075 toc08
12
C
CLK
= 30pF
10
CLK FALL TIME (ns)
8
6
4
2
0
-50
-25
0
25
50
75
100
256
125
4
5
6
7
8
9 10 11 12 13 14 15
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
3
Push-Pull FET Driver with Integrated Oscillator
and Clock Output
MAX5075
Typical Operating Characteristics (continued)
(V
CC
= +12V, R
RT
= 124kΩ, NDRV_ = open, CLK = open.)
OSCILLATOR FREQUENCY vs. R
RT
MAX5075 toc09
NDRV FREQUENCY
vs. CLK FREQUENCY
MAX5075 toc10
MAX5075A WAVEFORM
MAX5075 toc11
10,000
OSCILLATOR FREQUENCY (kHz)
800
700
NDRV FREQUENCY (kHz)
R
RT
= 124kΩ
NDRV1
5V/div
1000
MA
X50
7
600
500
400
300
200
100
5A
M
A
0
X5
75
B
100
X5
MA
075
C
NDRV2
5V/div
10
10
100
R
RT
(kΩ)
1000
0
0
250
500
750
1000
1250
1500
2µs/div
CLK FREQUENCY (kHz)
CLK
5V/div
MAX5075B WAVEFORM
MAX5075 toc12
MAX5075C WAVEFORM
MAX5075 toc13
R
RT
= 124kΩ
NDRV1
5V/div
R
RT
= 124kΩ
NDRV1
5V/div
NDRV2
5V/div
NDRV2
5V/div
CLK
5V/div
2µs/div
4µs/div
CLK
5V/div
4
_______________________________________________________________________________________
Push-Pull FET Driver with Integrated Oscillator
and Clock Output
Pin Description
PIN
1
2
3
4
5
6
7
8
EP
NAME
CLK
I.C.
RT
DGND
PGND
NDRV1
NDRV2
V
CC
EP
FUNCTION
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.
Internal Connection. Connect to ground. Internal function.
Oscillator Timing Resistor Connection. Bypass RT with a 1nF capacitor to DGND. Connect a resistor
from RT to DGND to set the internal oscillator.
Digital Ground. Connect DGND to ground plane.
Power Ground. Connect PGND to ground plane.
Gate Driver 1. Connect NDRV1 to the gate of the external n-channel FET.
Gate Driver 2. Connect NDRV2 to the gate of the external n-channel FET.
Power-Supply Input. Bypass V
CC
to PGND with 0.1µF
||
1µF ceramic capacitors.
Exposed Pad. Internally connected to DGND. Connect exposed pad to ground plane.
MAX5075
MAX5075
A (1x)
B (2x)
V
CC
5V
LDO
C (4x)
Q
Q
Q
T-FF
Q
NDRV2
UVLO 3.5V
V
CC
NDRV1
CLK
Q
Q
RT
DGND
OSC
INTERNAL
FUNCTION
PGND
I.C.
Figure 1. MAX5075 Functional Diagram
_______________________________________________________________________________________
5
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