19-3974; Rev 1; 4/07
KIT
ATION
EVALU
E
BL
AVAILA
High-Speed, Dual-Phase Driver
with Integrated Boost Diodes
General Description
Features
♦
Dual-Phase Synchronous Buck Driver
♦
Integrated Bootstrap Diodes
♦
Up to 26V System Input Voltage
♦
6A Peak Gate Drive Current
♦
Capable of 30A per Phase
♦
0.4Ω/0.9Ω Low-Side, 0.7Ω/1.0Ω High-Side
Drivers (typ)
♦
Typical 11ns Rise/Fall Times with 3000pF Load
♦
Adaptive Dead-Time Control
♦
User-Programmable Delay Time
♦
Enable Function with 0.04µA (typ) Quiescent
Current in Shutdown
♦
Space-Saving, Lead-Free, 16-Pin QSOP
MAX8811
The MAX8811 2-phase gate driver controls power
MOSFETs in multiphase synchronous step-down con-
verter applications, providing up to 30A output current
per phase. The MAX8811 and MAX8810A (multiphase
power-supply controller) combine to provide an efficient,
low-cost solution for a wide range of multiphase power-
supply applications. The MAX8811 handles system input
voltages up to 26V. Each MOSFET driver is capable of
driving 3000pF capacitive loads with 11ns typical rise
and fall times.
Adaptive shoot-through protection circuitry is imple-
mented to prevent shoot-through currents for the “high-
side off to low-side on” transition. A programmable
delay is provided for the “low-side off to high-side on”
transition. This maximizes overall converter efficiency
while supporting operation with a variety of MOSFETs.
The MAX8811 provides an easy upgrade path from the
MAX8523 dual driver. Integrated bootstrap diodes
reduce external component count, while an enable
input provides flexibility for power sequencing. The
MAX8811 is available in a space-saving, 16-pin QSOP.
Ordering Information
PART
MAX8811EEE+
TEMP RANGE
-40°C to +85°C
PIN-
PACKAGE
16 QSOP
PKG
CODE
E16-4
Applications
Processor Core Voltage Regulators
Multiphase Buck Converters
Voltage-Regulator Modules (VRMs)
Switching Power Supplies
DC-DC Converter Modules
+Denotes
a lead-free package.
Pin Configuration
Typical Operating Circuit
GATE-DRIVE SUPPLY
4.5V TO 7V
4
POWER INPUT
UP TO 26V
VL1
VL2
DH1
BST1
LX1
DL1
8
DLY
PGND1
2
1
3
5
6
OUTPUT
+
TOP VIEW
BST1 1
DH1 2
LX1 3
VL1 4
DL1 5
PGND1 6
EN 7
DLY 8
+
16 BST2
15 DH2
14 LX2
13
MAX8811
13 VL2
12 DL2
11 PGND2
10 PWM2
OFF
ON
MAX8811
DH2
7
9
EN
PWM1
BST2
LX2
DL2
PGND2
15
16
14
12
11
9
PWM1
QSOP
PWM CONTROL
SIGNALS
10 PWM2
________________________________________________________________
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.
High-Speed, Dual-Phase Driver
with Integrated Boost Diodes
MAX8811
ABSOLUTE MAXIMUM RATINGS
DLY, EN, PWM_, DL_ to PGND_.................-0.3V to (V
VL_
+ 0.3V)
BST_ to PGND_ ............................................-0.3V to (V
LX_
+ 8V)
BST_ to VL_ ...............................................................-1V to +30V
LX_ to PGND_............................................................-1V to +28V
DH_ to PGND_.........................................-0.3V to (V
BST_
+ 0.3V)
DH_, BST_ to LX_ .....................................................-0.3V to +8V
VL_ to PGND_ ..........................................................-0.3V to +8V
DH_, DL_ Current ................................................. ±200mA RMS
VL_ to BST_ Internal Diode Current .........................±50mA RMS
PGND1 to PGND2 .................................................-0.3V to +0.3V
Continuous Power Dissipation (T
A
= +70°C)
16-Pin QSOP (derate 8.3 mW/°C above +70°C)......666.7 mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°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
DLY
= V
EN
= V
BST_
= V
VL_
= 6.5V, V
PGND_
= V
LX_
= V
PWM_
= 0V,
T
A
= -40°C to +85°C,
unless otherwise noted. Typical values are
at T
A
= +25°C.) (Note 1)
PARAMETER
GENERAL
VL_ Input Voltage Range
LX Operating Range
VL_ Undervoltage Lockout
(UVLO)
Supply Current (per Channel)
I
BST_
+ I
VL_
Shutdown Supply Current
(per Channel) I
BST_
+ I
VL_
PWM_
Input Leakage
Input Voltage High Threshold
Input Voltage Low Threshold
Input Threshold Hysteresis
EN
Input Leakage
Input Voltage High Threshold
Input Voltage Low Threshold
Input Voltage Hysteresis
DLY
Delay Disable Threshold
V
VL_
- V
DLY
0.8
1.2
V
0.8
0.5
V
PWM_
= 0V or 7.0V, V
EN
= 0V or 7.0V
0.01
2.6
µA
V
V
V
1.2
20
V
PWM_
= 0V or 7.0V, V
EN
= 0V or 7.0V
0.01
3.5
µA
V
V
%
V
VL_
rising, 250mV hysteresis (typ)
V
PWM__
= 0V
V
PWM__
= V
DLY
= V
VL_
V
EN
= 0V, V
PWM_
= 0V or V
VL_
3.25
0.7
1.4
0.04
4.5
7
26
3.8
1.5
2
1
V
V
V
mA
µA
CONDITIONS
MIN
TYP
MAX
UNITS
2
_______________________________________________________________________________________
High-Speed, Dual-Phase Driver
with Integrated Boost Diodes
ELECTRICAL CHARACTERISTICS (continued)
(V
DLY
= V
EN
= V
BST_
= V
VL_
= 6.5V, V
PGND_
= V
LX_
= V
PWM_
= 0V,
T
A
= -40°C to +85°C,
unless otherwise noted. Typical values are
at T
A
= +25°C.) (Note 1)
PARAMETER
GATE DRIVER SPECIFICATIONS
V
PWM_
= V
VL_
,
sourcing current
DH_ Driver Resistance
V
PWM_
= 0V,
sinking current
V
PWM_
= 0V,
sourcing current
DL_ Driver Resistance
V
PWM_
= V
VL_
,
sinking current
DH_ Rise Time (t
rDH
)
DH_ Fall Time (t
fDH
)
DL_ Rise Time (t
rDL
)
DL_ Fall Time (t
fDL
)
V
PWM_
= V
VL_
V
PWM_
= 0V
V
PWM_
= 0V
V
PWM_
= V
VL_
V
PWM_
falling
(t
pDHf
)
V
PWM_
= V
VL
_ ,
V
DL
_ falling (t
pDHr
)
V
PWM_
rising
(t
pDLf
)
V
PWM_
= GND,
LX falling (t
pDLr
)
INTERNAL BOOST DIODE SPECIFICATIONS
On-Resistance
THERMAL SHUTDOWN
Thermal Shutdown
Rising temperature, hysteresis = 15°C (typ)
+165
°C
I
BST_
= 40mA
6
Ω
V
VL_
= 6.5V, I
DL_
= 0.1A
V
BST_
= 6.5V, 3000pF load
V
BST_
= 6.5V, 3000pF load
V
VL_
= 6.5V, 3000pF load
V
VL_
= 6.5V, 3000pF load
0.4
14
9
11
8
20
V
BST_
= 6.5V
14
12
V
BST_
- V
LX_
= 6.5V
16
ns
ns
0.7
ns
ns
ns
ns
V
BST_
= 6.5V, I
DH_
= 0.1A
V
VL_
= 6.5V, I
DL_
= -0.1A
0.7
0.9
1.1
Ω
1.5
V
BST_
= 6.5V, I
DH_
= -0.1A
1.0
1.6
CONDITIONS
MIN
TYP
MAX
UNITS
MAX8811
DH_ Propagation Delay
DL_ Propagation Delay
Note 1:
Specifications at -40°C guaranteed by design.
_______________________________________________________________________________________
3
High-Speed, Dual-Phase Driver
with Integrated Boost Diodes
MAX8811
Typical Operating Characteristics
(V
VL1
= V
VL2
= V
EN
= V
DLY
= 6.5V, 3000pF capacitive load, T
A
= +25°C, unless otherwise noted.)
VL_ POWER DISSIPATION
vs. LOAD CAPACITANCE
MAX8811toc02
VL_ POWER DISSIPATION vs. PER-PHASE
SWITCHING FREQUENCY
MAX8811toc01
DL RISE/FALL
vs. LOAD CAPACITANCE
MAX8811toc03
700
VL_ POWER DISSIPATION (mW)
600
500
400
300
200
100
0
0
200
400
600
800
400
350
VL_ POWER DISSIPATION (mW)
300
250
200
150
100
50
0
f
SW
= 200kHz
1000
3000
5000
30
25
RISE/FALL TIME (ns)
20
DL RISE
15
10
5
0
1000
3000
f
SW
= 200kHz
5000
DL
1000
7000
7000
f
S
(kHz)
DH/DL LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
DH RISE/FALL TIME
vs. LOAD CAPACITANCE
MAX8811toc04
RISE AND FALL TIMES
vs. TEMPERTURE
MAX8811toc05
VL_ SUPPLY CURRENT vs. PER-PHASE
SWITCHING FREQUENCY
MAX8811toc06
30
25
RISE/FALL TIME (ns)
20
DH RISE
15
DH FALL
10
5
0
0
2000
4000
6000
16
14
12
TIME (ns)
10
8
6
4
2
3000pF LOAD
0
DH FALL
DL FALL
DH RISE
DL RISE
120
100
80
60
40
20
0
VL_ SUPPLY CURRENT (mA)
8000
-40
-15
10
35
60
85
0
200
400
600
800
1000
LOAD CAPACITANCE (pF)
TEMPERATURE (°C)
f
S
(kHz)
PROPAGATION DELAY
vs. TEMPERATURE
MAX8811toc07
PROGRAMMABLE DELAY
vs. R
DLY
MAX8811toc11
25
tpDHf
20
tpDLr
120
100
80
60
40
20
0
TIME (ns)
15
tpDHr
10
tpDLf
5
0
-40
-15
10
35
60
85
TEMPERATURE (°C)
DELAY (ns)
0
10 20 30 40 50 60 70 80 90 100
R
DLY
(kΩ)
4
_______________________________________________________________________________________
High-Speed, Dual-Phase Driver with
Integrated Boost Diodes
Typical Operating Characteristics (continued)
(V
VL1
= V
VL2
= V
EN
= V
DLY
= 6.5V, 3000pF capacitive load, T
A
= +25°C, unless otherwise noted.)
SWITCHING WAVEFORMS
MAX8811toc09
MAX8811
VBST_ AND VL_ WAVEFORMS
MAX8811toc10
VPWM
5V/div
VL (AC-COUPLED)
500mV/div
VLX
10V/div
VDL
5V/div
VBST (AC-COUPLED)
200mV/div
VDH
5V/div
100ns/div
f
SW
= 250kHz
1μs/div
VLX
10div
Pin Description
PIN
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
NAME
BST1
DH1
LX1
VL1
DL1
PGND1
EN
DLY
PWM1
PWM2
PGND2
DL2
VL2
LX2
DH2
BST2
FUNCTION
Boost Capacitor Connection for Phase 1. Connect a 0.22µF ceramic capacitor between BST1 and LX1.
High-Side Gate-Driver Output for Phase 1. DH1 is pulled low during shutdown and UVLO.
Inductor Connection for Phase 1
Gate-Drive Supply for DL1. Connect VL1 to a 4.5V to 7V supply. VL1 must be connected to VL2
externally. Bypass the VL1/VL2 connection with a 2.2µF or larger ceramic capacitor to the power ground
plane.
Low-Side Gate-Driver Output for Phase 1. DL1 is pulled low during shutdown and UVLO.
Power Ground for DL1. Connect PGND1 and PGND2 to the power ground plane at the IC.
Enable Input. Drive EN high for normal operation, or low for shutdown.
Delay Time Setting Input. Connect a resistor from DLY to PGND1 to set the dead time between DL falling
and DH rising, or connect DLY to VL1 to use the default delay.
PWM Logic Input for Phase 1. DH1 is high when PWM1 is high; DL1 is high when PWM1 is low.
PWM Logic Input for Phase 2. DH2 is high when PWM2 is high; DL2 is high when PWM2 is low.
Power Ground for DL2. Connect PGND1 and PGND2 to the power ground plane at the IC.
Low-Side Gate-Driver Output for Phase 2. DL2 is pulled low during shutdown and UVLO.
Gate-Drive Supply for DL2. Connect VL2 to a 4.5V to 7V supply. VL1 must be connected to VL2
externally. Bypass the VL1/VL2 connection with a 2.2µF or larger ceramic capacitor to the power ground
plane.
Inductor Connection for Phase 2
High-Side Gate-Driver Output for Phase 2. DH2 is pulled low during shutdown and UVLO.
Boost Capacitor Connection for Phase 2. Connect a 0.22µF ceramic capacitor between BST2 and LX2.
_______________________________________________________________________________________
5
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