MAX17606
Secondary-Side Synchronous MOSFET Driver
for Flyback Converters
General Description
The MAX17606 is a secondary-side synchronous driver
and controller specifically designed for the isolated flyback
topology operating in Discontinuous Conduction Mode
(DCM) or Border Conduction Mode (BCM). By replacing
the secondary diode with a MOSFET, the device improves
the efficiency and simplifies thermal management. The
7V V
DRV
of the device makes it suitable for switching
both logic-level and standard MOSFETs used for flyback
synchronous rectification. The 36V input voltage allows
it to drive from either the output voltage or rectified drain
voltage of the secondary MOSFET. Programmable minimum
on and off-times provide flexibility needed to handle
transformer parasitic element-related ringing in a robust
manner. With 2A/4A source/sink currents, the MAX17606
is ideal for driving low R
DS(on)
power MOSFETs with fast
gate transition times.
Benefits and Features
●
Wide 4.5V to 36V Input
●
2A/4A Peak Source/Sink Gate Drive Currents
●
Suitable for Discontinuous Conduction Mode (DCM),
Border Conduction Mode (BCM)
●
320µA (typ) Low Quiescent Current
●
Programmable Turn-Off Trip Point
●
Programmable Minimum Off-Time to Handle DCM
Ringing
●
Thermal-Shutdown Protection
●
6-Lead SOT-23 Package
Applications
● High-Efficiency Isolated Flyback Converters
Ordering Information
appears at end of data sheet.
Typical Application Circuit for 24V to 5V, 3A Isolated Flyback Converter
V
IN
C1
4.7µF
x4
C4
1nF
PGND
R5
47Ω
D1
T1
V
OUT
5V,3A
C9
100µF
6x
0
C10
2.2µF
0
T
OFF
U2
R14
100kΩ
C2
0.1µF
SS
R1
49.9kΩ
IN
R9
4.7Ω
U1
MAX17597
N
DRV
R6
220Ω
CS
C5
1nF
R7
0.02Ω
0
U3
V
DRV
4
C6
2.2µF
3
R4
22kΩ
R8
470kΩ
0
2
U4
1
C8
0.22µF
R11
470Ω
Q1
Q2
RT
R10
2.74kΩ
DRN
GATE
C7
2.2µF
V
IN
V
IN
EN/UVLO
DITHER
OVI
SGND
EP
COMP
R2
49.9kΩ
C3
R3
22nF
10.5kΩ
MAX17606
V
DRV
GND
0
V
OUT
R12
1.5kΩ
FB
R13
487Ω
T1-WE750342955
Q1-FDMS86102 LZ
Q2-BSZ040N04LSG
19-7758; Rev 0; 10/15
MAX17606
Secondary-Side Synchronous MOSFET Driver
for Flyback Converters
Absolute Maximum Ratings
VIN to GND ..........................................................-0.3V to +40V
TOFF to GND .........................................................-0.3V to +6V
DRN (low impedance source) to GND .................-0.3V to +70V
DRN to GND (up to 5mA of pull out current) .......... Self-Limiting
GATE to GND ..........................................-0.3V to VDRV + 0.3V
VDRV to GND ..............................-0.3V to Min (V
IN
+ 0.3, 18)V
Continuous Power Dissipation (single-layer board)
(T
A
= +70°C, derate 2.7mW/°C above +70°C.)........219.1mW
Continuous Power Dissipation (multilayer board)
(T
A
= +70°C, derate 9.1mW/°C above +70°C.)........727.3mW
Operating Temperature Range ........................ -40°C to +125°C
Junction Temperature ................................................... +150°C
Storage Temperature Range ........................... -40°C to +150°C
Soldering Temperature (reflow) .................................... +260°C
Package Thermal Characteristics
(Note 1)
SOT-23 6L
Junction-to-Ambient Thermal Resistance (θ
JA
) ........110°C/W
Junction-to-Case Thermal Resistance (θ
JC
) ...............50°C/W
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.maximintegrated.com/thermal-tutorial.
Electrical Characteristics
V
IN
= 12V, C
VIN
= 100nF, C
VDRV
= 2.2μF, GATE = OPEN, DRN = 0V, GND = 0V, R
TOFF
= 40.2kΩ, T
A
= T
J
= -40°C to +125°C, unless
otherwise noted. Typical values are at T
A
= +25°C. All voltages are referenced to GND, unless otherwise noted. (Note 2)
PARAMETER
V
IN
V
IN
Operating Range
V
IN
Quiescent Current
V
IN
Switching Current
V
DRV
V
DRV
Regulation Voltage
V
DRV
Regulation Voltage
V
DRV
Dropout Voltage
V
DRV
Current Limit
V
DRV
Undervoltage
Lockout
DRN
Maximum Drain Operating
Voltage
GATE Turn-On Detect
Threshold
GATE Turn-Off Detect
Threshold
DRN Rising Threshold for
T
OFF
Enable
DRN Bias Current
V
DRN
V
GATE-ON
V
GATE-OFF
V
DRN-TOFF_
EN
SYMBOL
V
IN
I
Q
I
SW
CONDITIONS
MIN
4.5
TYP
MAX
36
UNITS
V
µA
µA
DRN = 2V, no switching
DRN switching -150mV to +2V,
300kHz, 50% duty cycle
1mA ≤ V
DRV
≤ 20mA
I
VDRV
= 1mA; 8.5V ≤ V
IN
≤ 36V
I
VDRV
= 20mA ,V
IN
= 4.5V
V
DRV
= 6V; V
IN
= 8.5V
V
DRV
rising
V
DRV
falling
6.6
6.6
4.1
26.5
4.0
3.75
320
600
450
V
DRV_LOAD
V
DRV_LINE
V
DRV-DO
I
VDRV
V
DRV-UVR
V
DRV-UVH
7.0
7.0
4.3
55
4.25
4
7.4
7.4
V
V
V
mA
4.47
4.25
V
V
60
-150
24
DRN voltage rising
R
TOFF
= 40.2KΩ, DRN = 0V
26.5
-94
30
0.87
30.5
34.5
35
V
mV
mV
V
µA
IDRN
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2
MAX17606
Secondary-Side Synchronous MOSFET Driver
for Flyback Converters
Electrical Characteristics (continued)
V
IN
= 12V, C
VIN
= 100nF, C
VDRV
= 2.2μF, GATE = OPEN, DRN = 0V, GND = 0V, R
TOFF
= 40.2kΩ, T
A
= T
J
= -40°C to +125°C, unless
otherwise noted. Typical values are at T
A
= +25°C. All voltages are referenced to GND, unless otherwise noted. (Note 2)
PARAMETER
GATE Output Pullup
Resistance
GATE Output Pulldown
Resistance
GATE Peak Source Current
GATE Peak Sink Current
Turn-On Propagation Delay
Turn-Off Propagation Delay
T
OFF
Programmable range
T
OFF
Accuracy
Minimum On-Time
T
ON_MIN
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
SWITCHING CHARACTERISTICS (GATE, T
OFF
)
R
ON-P
R
ON-N
I
G-SOURCE
I
G-SINK
T
ON-D
T
OFF-D
T
OFF
R
TOFF
= 40.2kΩ
R
TOFF
= 150kΩ
DRN falling to gate rising
DRN rising to gate falling
115
315
1150
150
425
1550
240
V
IN
= V
DRV
7V, I
GATE
= -50mA
V
IN
= 7V, I
GATE
= 190mA
1.5
0.5
2
4
26
32
40
50
1550
540
2000
330
2.8
0.9
Ω
Ω
A
A
ns
ns
ns
ns
ns
ns
Note 2:
Limits are 100% tested at T
A
= +25°C. Limits over the temperature range and relevant supply voltage range are guaranteed
by design and characterization.
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MAX17606
Secondary-Side Synchronous MOSFET Driver
for Flyback Converters
Typical Operating Characteristics
V
IN
=13V,V
GND
= 0V, R
TOFF
= 100kΩ, R
DRN
= 2.74kΩ, C
VDRV
= 2.2µF, T
A
= +25°C, unless otherwise noted.
100
95
90
EFFICIENCY (%)
85
80
75
70
65
60
55
50
0
EFFICIENCY vs. LOAD CURRENT
V
IN
= 18V
toc1
100
95
90
EFFICIENCY (%)
85
80
75
70
65
60
55
50
EFFICIENCY COMPARISON
V
IN
= 24V,WITH
MOSFET
V
IN
= 24V,WITH DIODE
toc2
120
100
80
TIME (ns)
GATE RISE AND FALL TIME vs. CHARGE
toc3
V
IN
= 24V
V
IN
= 36V
RISE TIME
60
40
20
0
FALL TIME
MOSFET-BSZ040N04LSG
DIODE-STPS30M60DJF-TR
SEE FIGURE 2 TYPICAL
APPLICATION CIRCUIT
0
1000
2000
3000
LOAD CURRENT (mA)
1000
2000
3000
0
50
CHARGE (nC)
100
150
LOAD CURRENT (mA)
380
360
340
QUIESCENT CURRENT (I
Q
)
vs. TEMPERATURE
toc4
V
DRV
vs. TEMPERATURE
toc5
FULL-LOAD STEADY-STATE WAVEFORM
FOR DCM OPERATION, (V
IN
= 24V, I
OUT
= 3A)
toc6
7.40
V
DRV
VOLTAGE (V)
I
Q
(µA)
320
300
280
260
240
220
200
7.20
V
DRAIN
7.00
5V/div
GATE
6.80
SEE FIGURE 2 TYPICAL
APPLICATION CIRCUIT
6.60
-40
-20
0
20
40
60
80
100 120 140
-40
-20
0
20
40
60
80
100 120 140
1µS/div
TEMPERATURE (°C)
TEMPERATURE (°C)
FULL-LOAD, STEADY-STATE WAVEFORM
FOR BCM OPERATION, V
IN
= 18V, I
OUT
= 3A
toc7
LOAD TRANSIENT RESPONSE
(LOAD CURRENT FROM 1.5A TO 3A ON 5V)
toc8
5V OUTPUT, 3A LOAD CURRENT
BODE PLOT
toc9
V
OUT
(AC)
V
DRAIN
200mV/div
5V/div
GATE
1A/div
I
OUT
SEE FIGURE 2 TYPICAL
APPLICATION CIRCUIT
SEE FIGURE 2 TYPICAL
APPLICATION CIRCUIT
1µS/div
F
CR
= 7.622kHz
PHASE MARGIN = 73.082°
SEE FIGURE 2 TYPICAL
APPLICATION CIRCUIT
1mS/div
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4
MAX17606
Secondary-Side Synchronous MOSFET Driver
for Flyback Converters
Pin Configurations
TOP VIEW
V
IN
1
+
6 T
OFF
GND
2
MAX17606
5 V
DRV
DRN
3
4 GATE
SOT-23 6L
Pin Description
PIN
1
2
3
4
5
6
NAME
V
IN
GND
DRN
GATE
VDRV
TOFF
FUNCTION
Input Voltage. Connect at least 2.2µF X7R ceramic capacitor from VIN to GND for bypassing.
IC Ground. The external MOSFET source should be kelvin connected to this pin. See the
MAX17606 EV kit PCB for example layout.
Drain Sense Pin of the External MOSFET. Connect the external MOSFET drain to this pin through a
resistor. See the MAX17606 EV kit PCB for example layout.
External nMOSFET GATE Driver Output.
LDO Output and Driver Input. Connect a 2.2µF bypass capacitor from V
DRV
pin to GND, as close
as possible to the IC. See the MAX17606 EV kit PCB for example layout.
Connect a resistor from T
OFF
to GND to set the programmable minimum off time.
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