19-3663; Rev 1; 6/07
Push-Pull FET Driver with Integrated Oscillator
and Programmable Clock Output
General Description
The MAX5077 is a +4.5V to +15V push-pull, current-fed
topology driver subsystem with an integrated oscillator
used 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. The MAX5077 features a
programmable accurate integrated oscillator with a
synchronizing clock output to synchronize an external
PWM regulator. A single external resistor programs the
internal oscillator frequency from 50kHz to 1.5MHz.
The MAX5077 incorporates dual MOSFET drivers with
±3A peak drive currents and 50% duty cycle. The
MOSFET drivers generate complementary signals to
drive external ground-referenced n-channel MOSFETs.
The MAX5077 clock output frequency is programmable
by logic inputs to set the clock output to 1x, 2x, or 4x
the MOSFET’s driver frequency.
The MAX5077 is available in a 14-pin exposed pad
TSSOP package and is specified over the -40°C to
+125°C operating temperature range.
Features
♦
Dedicated Current-Fed, Push-Pull Driver
Subsystem
♦
Oscillator Frequency Programmable from 50kHz
to 1.5MHz
♦
Single +4.5V to +15V Supply Voltage Range
♦
±3A Peak Gate-Drive Current
♦
1mA Operating Current at 250kHz with No
Capacitive Load
♦
Selectable Synchronizing Clock Frequency for a
Preceding PWM Stage
♦
Thermally Enhanced 14-Pin TSSOP
♦
-40°C to +125°C Operating Temperature Range
MAX5077
Ordering Information
PART
TEMP RANGE
-40°C to +125°C
PIN-PACKAGE
14 TSSOP-EP*
PKG
CODE
U14E-3
Applications
Current-Fed Power Supplies
Power-Supply Building Subsystems
Push-Pull Driver Subsystems
MAX5077AUD
*EP
= Exposed paddle.
Pin Configuration appears at end of data sheet.
Typical Operating Circuit
V
IN
V
IN
DRVH
V
OUT
SYNCIN
PWM
CONTROLLER
V
CC
CLK
MAX5077
V
CC
SEL1
I.C.
NDRV1
SEL2
DGND
PGND
NDRV2
DRVL
GND
4.7kΩ
1nF
GND
RT
AGND
________________________________________________________________
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 Programmable Clock Output
MAX5077
ABSOLUTE MAXIMUM RATINGS
V
CC
to AGND, DGND, PGND.................................-0.3V to +18V
PGND, DGND to AGND ........................................-0.3V to +0.3V
SEL1, SEL2 to DGND .............................................-0.3V to +18V
CLK, RT to AGND.....................................................-0.3V to +6V
NDRV1, NDRV2 to PGND...........................-0.3V to (V
CC
+ 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)
14-Pin TSSOP (derate 20.8mW/°C above +70°C) .....1667mW
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, SEL1 = V
CC
, SEL2 = DGND, R
RT
= 124kΩ, NDRV1 = NDRV2 = open, T
A
= T
J
= -40°C to +125°C, unless otherwise
noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
SUPPLY
Input Voltage Supply Range
Static Supply Current
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
3.9
3.35
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
CCST
I
CCSW
V
UVLO
SEL2 = SEL1 = DGND, drivers not switching
SEL2 = DGND, SEL1 = V
CC
, f
OSC
= 250kHz
V
CC
rising
3
4.5
150
1
3.5
300
15.0
320
3
4
V
µA
mA
V
mV
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
2
_______________________________________________________________________________________
Push-Pull FET Driver with Integrated Oscillator
and Programmable Clock Output
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +12V, SEL1 = V
CC
, SEL2 = DGND, R
RT
= 124kΩ, NDRV1 = NDRV2 = open, T
A
= T
J
= -40°C to +125°C, unless otherwise
noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
SEL_ INPUTS
Input Current
Input High Voltage
Input Low Voltage
V
IH
V
IL
0V
≤
V
SEL_
≤
V
CC
3
2.5
2
1.5
1
µA
V
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX5077
Note 1:
The MAX5077 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 MAX5077 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.
Typical Operating Characteristics
(V
CC
= +12V, SEL1 = V
CC
, SEL2 = DGND, R
RT
= 124kΩ, NDRV1 = NDRV2 = open, CLK = open.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX5077 toc01
STATIC SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX5077 toc02
SUPPLY CURRENT
vs. C
CLK
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
MAX5077 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
170
160
STATIC SUPPLY CURRENT (µA)
150
140
130
120
110
100
90
80
T
A
= -40°C
T
A
= +25°C
T
A
= +125°C
1.50
9 10 11 12 13 14 15
4
5
6
7
8
9 10 11 12 13 14 15
0
20
40
60
80
100
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
C
CLK
(pF)
SUPPLY CURRENT
vs. TEMPERATURE
MAX5077 toc04
CLK RISE TIME
vs. SUPPLY VOLTAGE
45
40
CLK RISE TIME (ns)
35
30
25
20
15
10
5
0
36.5
4
5
6
7
8
9 10 11 12 13 14 15
-50
-25
C
CLK
= 30pF
MAX5077 toc05
CLK RISE TIME
vs. TEMPERATURE
C
CLK
= 30pF
39.0
CLK RISE TIME (ns)
38.5
38.0
37.5
37.0
MAX5077 toc06
1.20
1.18
1.16
SUPPLY CURRENT (mA)
1.14
1.12
1.10
1.08
1.06
1.04
1.02
1.00
-50
-25
0
25
50
75
100
f
OSC
= 250kHz
50
39.5
125
0
25
50
75
100
125
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
_______________________________________________________________________________________
3
Push-Pull FET Driver with Integrated Oscillator
and Programmable Clock Output
MAX5077
Typical Operating Characteristics (continued)
(V
CC
= +12V, SEL1 = V
CC
, SEL2 = DGND, R
RT
= 124kΩ, NDRV1 = NDRV2 = open, CLK = open.)
CLK FALL TIME
vs. SUPPLY VOLTAGE
MAX5077 toc07
CLK FALL TIME
vs. TEMPERATURE
MAX5077 toc08
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
MAX5077 toc09
MAX5077 toc12
MAX5077 toc11
14
12
CLK FALL TIME (ns)
10
8
6
4
2
0
4
5
6
7
8
C
CLK
= 30pF
12
C
CLK
= 30pF
10
CLK FALL TIME (ns)
8
6
4
2
0
256
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)
OSCILLATOR FREQUENCY vs. R
RT
MAX5077 toc10
NDRV FREQUENCY
vs. CLK FREQUENCY
800
700
MAX5077 WAVEFORM
(f
CLK
:f
NDRV
= 1x, R
RT
= 124kΩ)
10,000
OSCILLATOR FREQUENCY (kHz)
IGH
NDRV FREQUENCY (kHz)
500
400
300
200
, SE
L1
1000
=H
600
LOW
100
SE
=
L2
SEL
HI
2=
,S
GH
EL
L
1=
OW
NDRV2
5V/div
S
100
10
10
100
R
RT
(kΩ)
1000
0
0
250
=
EL2
HIG
H,
1
SEL
=H
IGH
NDRV1
5V/div
CLK
5V/div
500
750
1000
1250
1500
2µs/div
CLK FREQUENCY (kHz)
MAX5077 WAVEFORM
(f
CLK
:f
NDRV
= 2x, R
RT
= 124kΩ)
MAX5077 toc13
MAX5077 WAVEFORM
(f
CLK
:f
NDRV
= 4x, R
RT
= 124kΩ)
MAX5077 toc14
NDRV2
5V/div
NDRV2
5V/div
NDRV1
5V/div
NDRV1
5V/div
CLK
5V/div
2µs/div
4µs/div
CLK
5V/div
4
_______________________________________________________________________________________
Push-Pull FET Driver with Integrated Oscillator
and Programmable Clock Output
Pin Description
PIN
1, 8
2
3
4, 14
5
6
7
9
10
11
12
13
EP
NAME
N.C.
SEL1
CLK
I.C.
RT
AGND
DGND
PGND
NDRV1
NDRV2
V
CC
SEL2
EP
No Connection. Must be left unconnected.
CLK Frequency Ratio Select Input. Use SEL1 and SEL2 to set f
CLK
to f
NDRV_
frequency ratio (see Table 1).
Synchronizing Clock Output. Clock output with a ±10mA peak current drive that can be used to synchronize
an external PWM regulator. CLK/NDRV_ frequency has a 1x, 2x, or 4x ratio (see the
Synchronizing Clock
Output
section).
Connect to ground. Internal function.
Oscillator Timing Resistor Connection. Bypass RT with a series of a 4.7kΩ resistor and a 1nF capacitor to
AGND. Connect a resistor from RT to AGND to set the internal oscillator frequency.
Analog Ground. Connect AGND to ground plane.
Digital Ground. Connect DGND to ground plane.
Power Ground. Connect to ground plane.
Gate Driver 1. Connect NDRV1 to the gate of an external n-channel FET.
Gate Driver 2. Connect NDRV2 to the gate of an external n-channel FET.
Power-Supply Input. Bypass V
CC
to PGND with 0.1µF||1µF ceramic capacitors.
CLK Frequency Divisor Input. Use SEL1 and SEL2 to set f
CLK
to f
NDRV_
frequency ratio (see Table 1).
Exposed Pad. Internally connected to DGND. Connect exposed pad to ground plane.
FUNCTION
MAX5077
SEL1
MAX5077
UVLO 3.5V
V
CC
SEL2
V
CC
5V
LDO
DGND
NDRV2
Q
Q
Q
T-FF
Q
NDRV1
Q
Q
RT
AGND
OSC
INTERNAL
FUNCTION
PGND
I.C.
I.C.
N.C.
CLK
Figure 1. MAX5077 Functional Diagram
_______________________________________________________________________________________
5
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