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PDF ISL6741 Data sheet ( Hoja de datos )
| Número de pieza | ISL6741 | |
| Descripción | Flexible Double Ended Voltage and Current Mode PWM Controllers | |
| Fabricantes | Intersil | |
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Flexible Double Ended Voltage and Current Mode PWM
Controllers
ISL6740, ISL6741
The ISL6740, ISL6741 family of adjustable frequency, low
power, pulse width modulating (PWM) voltage mode (ISL6740)
and current mode (ISL6741) controllers is designed for a wide
range of power conversion applications using half-bridge, full
bridge, and push-pull configurations. These controllers provide
an extremely flexible oscillator that allows precise control of
frequency, duty cycle, and deadtime.
This advanced BiCMOS design features low operating current,
adjustable switching frequency up to 1MHz, adjustable soft-
start, internal and external over-temperature protection, fault
annunciation, and a bidirectional SYNC signal that allows the
oscillator to be locked to paralleled units or to an external
clock for noise sensitive applications.
Ordering Information
PART
NUMBER
(Notes 2, 3)
PART TEMP. RANGE
MARKING
(°C)
PACKAGE
PKG.
DWG. #
ISL6740IBZ 6740IBZ
(Note 1)
-40 to +105 16 Ld SOIC M16.15
(Pb-free)
ISL6740IVZ ISL67 40IVZ -40 to +105 16 Ld TSSOP M16.173
(Note 1)
(Pb-free)
ISL6741IB ISL6741IB -40 to +105 16 Ld SOIC M16.15
ISL6741IBZ 6741IBZ
(Note 1)
-40 to +105 16 Ld SOIC M16.15
(Pb-free)
ISL6741IVZ ISL67 41IVZ -40 to +105 16 Ld TSSOP M16.173
(Note 1)
(Pb-free)
NOTES:
1. Add “-T*” suffix for tape and reel. Please refer to TB347 for details
on reel specifications.
2. These Intersil Pb-free plastic packaged products employ special Pb-
free material sets, molding compounds/die attach materials, and
100% matte tin plate plus anneal (e3 termination finish, which is
RoHS compliant and compatible with both SnPb and Pb-free
soldering operations). Intersil Pb-free products are MSL classified
at Pb-free peak reflow temperatures that meet or exceed the Pb-
free requirements of IPC/JEDEC J STD-020.
3. For Moisture Sensitivity Level (MSL), please see device information
page for ISL6740, ISL6741. For more information on MSL please
see techbrief TB363.
ISL674x
x=
0
1
CONTROL MODE
Voltage Mode
Current Mode
Features
• Precision Duty Cycle and Deadtime Control
• 95µA Start-up Current
• Adjustable Delayed Overcurrent Shutdown and Re-start
(ISL6740)
• Adjustable Short Circuit Shutdown and Re-start
• Adjustable Oscillator Frequency Up to 2MHz
• Bidirectional Synchronization
• Inhibit Signal
• Internal Over-Temperature Protection
• System Over-Temperature Protection Using a Thermistor or
Sensor
• Adjustable Soft-start
• Adjustable Input Undervoltage Lockout
• Fault Signal
• Tight Tolerance Voltage Reference Over Line, Load, and
Temperature
• Pb-Free Available (RoHS Compliant)
Applications
• Telecom and Datacom Power
• Wireless Base Station Power
• File Server Power
• Industrial Power Systems
• DC Transformers and Buss Regulators
Pin Configuration
ISL6740, ISL6741
(16 LD SOIC, 16 LD TSSOP)
TOP VIEW
OUTA 1
GND 2
SCSET 3
CT 4
SYNC 5
CS 6
VERROR 7
UV 8
16 OUTB
15 VREF
14 VDD
13 RTD
12 RTC
11 OTS
10 FAULT
9 SS
December 2, 2011
FN9111.6
1 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 |Copyright Intersil Americas Inc. 2003, 2004, 2007, 2011. All Rights Reserved
Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries.
All other trademarks mentioned are the property of their respective owners.
1 page  
Typical Application (ISL6740) - 36V to 75V Input, Regulated 12V @ 8A Output (ISL6740EVAL2Z)
VIN+
L1
C2
QH
L3
CR5
T1
R26
QR1
C11
R8
SP1
QR3
+
+12V
C21
C13 C9 C8
TP1 R10
L2 RTN
C1 CR4
T2
36V TO 75V
R1
R2
CR3
C3
C7
C4
QL
U1
HIP2101
VDD LO
HB VSS
HO LI
HS HI
TP4
CR6
R27
C14
R11
QR2
CR2
R9
QR4
C12
CR1
R5
RT1
R14 R6
VREF
C10
TP2
+ 12V
C5
TP5
U3
C18
R19
R4
VIN-
TP6
R17
R7
Q5
D1
C6
R3
C15
R18
GND
OUTB
OUTA
VDD
VERROR
CS
CT
RTC
R12
C16
R13
C17
R15
R19 R20
R23
C22
R25 C20
R21 C19
U2
U4
D2 R24
5 Page 
ISL6740, ISL6741
The ISL6740, ISL6741 features a built-in soft-start. Soft-start is
implemented as a clamp on the error voltage input.
OTS - The non-inverting input to the over-temperature shutdown
comparator. The signal input at this pin is compared to an
internal threshold of VREF/2. If the voltage at this pin exceeds the
threshold, the Fault signal is asserted and the outputs are
disabled until the condition clears. There is a nominal 25μA
switched current source used for hysteresis. The amount of
hysteresis is adjustable by varying the source impedance of the
signal into this pin.
OTS may be used to monitor parameters other than temperature,
such as voltage. Any signal for which a high out-of-bounds
monitor is desired may utilize the OTS comparator.
FAULT - The Fault signal is asserted high whenever the outputs,
OUTA and OUTB, are disabled. This occurs during an over-
temperature fault, an input UV fault, a VREF UV fault, or during an
overcurrent (ISL6740) or short circuit shutdown fault. Fault can
be used to disable synchronous rectifiers whenever the outputs
are disabled.
Fault is a three-state output and is high impedance during the
soft-start cycle. Adding a pull-up resistor to VREF or a pull-down
resistor to ground determines the state of Fault during soft-start.
This feature allows the designer to use the Fault signal to enable
or disable output synchronous rectifiers during soft-start.
UV - Undervoltage monitor input pin. A resistor divider between
the input source voltage and GND sets the undervoltage lock out
threshold. The signal is compared to an internal 1.00V reference
to detect an undervoltage or inhibit condition.
CS - This is the input to the current sense comparator(s). The IC
has the PWM comparator for peak current mode control
(ISL6741) and an overcurrent protection comparator. The
overcurrent comparator threshold is set at 0.600V nominal.
The CS pin is shorted to GND at the end of each switching cycle.
Depending on the current sensing source impedance, a series
input resistor may be required due to the delay between the
internal clock and the external power switch. This delay may
allow an overlap such that the CS signal may be discharged while
the current signal is still active. If the current sense source is low
impedance, it will cause increased power dissipation.
ISL6740 - Exceeding the overcurrent threshold will start a
delayed shutdown sequence. Once an overcurrent condition is
detected, the soft-start charge current source is disabled. The
soft-start capacitor begins discharging through a 25μA current
source, and if it discharges to less than 4.25V (Sustained
Overcurrent Threshold), a shutdown condition occurs and the
OUTA and OUTB outputs are forced low. When the soft-start
voltage reaches 0.27V (Reset Threshold) a soft-start cycle begins.
An overcurrent condition must be absent for 50μs before the
delayed shutdown control resets. If the overcurrent condition
ceases, and an additional 50μs period elapses before the
shutdown threshold is reached, no shutdown occurs. The SS
charging current is re-enabled and the soft-start voltage is
allowed to recover.
ISL6741 - The ISL6741 current mode controller does not
shutdown due to an overcurrent condition. The pulse-by-pulse
current limit characteristic of peak current mode control limits
the output current to acceptable levels.
GND - Reference and power ground for all functions on this
device. Due to high peak currents and high frequency operation,
a low impedance layout is necessary. Ground planes and short
traces are highly recommended.
OUTA and OUTB - Alternate half cycle output stages. Each output
is capable of 0.5A peak currents for driving logic level power
MOSFETs or MOSFET drivers. Each output provides very low
impedance to overshoot and undershoot.
VREF - The 5.00V reference voltage output. +1%/-2% tolerance
over line, load and operating temperature. Bypass to GND with a
0.047μF to 2.2μF ceramic capacitor. Capacitors outside of this
range may cause oscillation.
SS - Connect the soft-start timing capacitor between this pin and
GND to control the duration of soft-start. The value of the
capacitor determines the rate of increase of the duty cycle during
start up, controls the overcurrent shutdown delay (ISL6740), and
the overcurrent and short circuit hiccup restart period.
SCSET - Sets the duty cycle threshold that corresponds to a short
circuit condition. A resistive divider between RTC and GND or RTD
and GND, or a voltage between 0V and 2V may be used to adjust
the SCSET threshold. If using a resistor divider from either RTC or
RTD, the impedance to GND affects the oscillator timing and
should be considered when determining the oscillator timing
components. Connecting SCSET to GND disables short circuit
shutdown and hiccup.
Functional Description
Features
The ISL6740, ISL6741 PWMs are an excellent choice for low cost
bridge and push-pull topologies for applications requiring
accurate duty cycle and deadtime control. With its many
protection and control features, a highly flexible design with
minimal external components is possible. Among its many
features are current mode control (ISL6741), adjustable soft-
start, overcurrent protection, thermal protection, bidirectional
synchronization, fault indication, and adjustable frequency.
Oscillator
The ISL6740, ISL6741 have an oscillator with a programmable
frequency range to 2MHz, which can be programmed with two
resistors and capacitor. The use of three timing elements, RTC,
RTD, and CT allow great flexibility and precision when setting the
oscillator frequency.
The switching period may be considered the sum of the timing
capacitor charge and discharge durations. The charge duration is
determined by RTC and CT. The discharge duration is determined
by RTD and CT.
tC ≈ 0.5 • RTC • CT
S
(EQ. 2)
tD ≈ 0.02 • RTD • CT
tSW = tC + tD = -F---S1---W---
S
S
(EQ. 3)
(EQ. 4)
11 FN9111.6
December 2, 2011
11 Page | ||
| Páginas | Total 28 Páginas | |
| PDF Descargar | [ Datasheet ISL6741.PDF ] | |
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