DATASHEET
ISL78840ASxH, ISL78841ASxH, ISL78843ASxH, ISL78845ASxH
Radiation Hardened, High Performance Industry Standard Single-Ended Current
Mode PWM Controller
The
ISL78840ASEH, ISL78841ASEH, ISL78843ASEH,
ISL78845ASEH, ISL78840ASRH, ISL78841ASRH,
ISL78843ASRH, ISL78845ASRH
are high performance,
radiation hardened drop-in replacements for the popular
28C4x and 18C4x PWM controllers suitable for a wide range of
power conversion applications including boost, flyback, and
isolated output configurations. Fast signal propagation and
output switching characteristics make these ideal products for
existing and new designs.
Features include up to 13.2V operation, low operating current,
90µA typical start-up current, adjustable operating frequency
to 1MHz and high peak current drive capability with 50ns rise
and fall times.
FN7952
Rev 2.00
Feb 23, 2018
Features
• Electrically screened to DLA SMD #5962-07249
• QML qualified per MIL-PRF-38535 requirements
• 1A MOSFET gate driver
• 90µA typical start-up current, 125µA maximum
• 35ns propagation delay current sense to output
• Fast transient response with peak current-mode control
• 9V to 13.2V operation
• Adjustable switching frequency to 1MHz
• 50ns rise and fall times with 1nF output load
• Trimmed timing capacitor discharge current for accurate
dead time/maximum duty cycle control
• 1.5MHz bandwidth error amplifier
• Tight tolerance voltage reference over line, load, and
temperature
• ±3% current limit threshold
• Pb-free available (RoHS compliant)
• Radiation environment:
- High dose rate (50 - 300rad(Si)/s). . . . . . . . . . 100krad(Si)
- Low dose rate (0.01rad(Si)/s) . . . . . . . . . . . . 100krad(Si)*
* Product capability established by initial characterization. The
“EH” version is acceptance tested on a wafer-by-wafer basis to
50krad(Si) at low dose rate. (Applies to ISL7884xASEH only)
Applications
• Current mode switching power supplies
• Isolated buck and flyback regulators
• Boost regulators
• Direction and speed control in motors
• Control of high current FET drivers
Related Literature
For a full list of related documents, visit our website
•
ISL78840ASEH, ISL78841ASEH, ISL78843ASEH,
ISL78845ASEH, ISL78840ASRH, ISL78841ASRH,
ISL78843ASRH,
and
ISL78845ASRH
product pages
TABLE 1. KEY DIFFERENCES BETWEEN FAMILY OF PARTS
PART NUMBER
ISL78840ASxH
ISL78841ASxH
ISL78843ASxH
ISL78845ASxH
RISING UVLO
(V)
7.0
7.0
8.4
8.4
MAXIMUM DUTY CYCLE
(%)
100
50
100
50
FN7952 Rev 2.00
Feb 23, 2018
Page 1 of 17
ISL78840ASxH, ISL78841ASxH, ISL78843ASxH, ISL78845ASxH
Ordering Information
ORDERING NUMBER
(Note
1)
5962R0724905VPC
5962R0724906VPC
5962R0724907VPC
5962R0724908VPC
5962R0724905VXC
5962R0724906VXC
5962R0724907VXC
5962R0724908VXC
5962R0724905V9A
5962R0724906V9A
5962R0724907V9A
5962R0724908V9A
5962R0724901V9A
PART NUMBER
(Note
2)
ISL78840ASEHVD
ISL78841ASEHVD
ISL78843ASEHVD
ISL78845ASEHVD
ISL78840ASEHVF
ISL78841ASEHVF
ISL78843ASEHVF
ISL78845ASEHVF
ISL78840ASEHVX
ISL78841ASEHVX
ISL78843ASEHVX
ISL78845ASEHVX
ISL78840ASRHVX
ISL78840ASRHX/SAMPLE (Note
3)
ISL78840ASRHF/PROTO (Note
3)
5962R0724901QXC
5962R0724901VXC
ISL78840ASRHQF
ISL78840ASRHVF
ISL78840ASRHD/PROTO (Note
3)
5962R0724901QPC
5962R0724901VPC
5962R0724902V9A
ISL78840ASRHQD
ISL78840ASRHVD
ISL78841ASRHVX
ISL78841ASRHX/SAMPLE (Note
3)
ISL78841ASRHF/PROTO (Note
3)
5962R0724902QXC
5962R0724902VXC
ISL78841ASRHQF
ISL78841ASRHVF
ISL78841ASRHD/PROTO (Note
3)
5962R0724902QPC
5962R0724902VPC
5962R0724903V9A
ISL78841ASRHQD
ISL78841ASRHVD
ISL78843ASRHVX
ISL78843ASRHX/SAMPLE (Note
3)
ISL78843ASRHF/PROTO (Note
3)
5962R0724903QXC
5962R0724903VXC
ISL78843ASRHQF
ISL78843ASRHVF
ISL78843ASRHD/PROTO (Note
3)
5962R0724903QPC
5962R0724903VPC
5962R0724904V9A
ISL78843ASRHQD
ISL78843ASRHVD
ISL78845ASRHVX
ISL78845ASRHX/SAMPLE (Note
3)
ISL78845ASRHF/PROTO (Note
3)
TEMP. RANGE
(°C)
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
PACKAGE
(RoHS Compliant)
8 Ld SBDIP
8 Ld SBDIP
8 Ld SBDIP
8 Ld SBDIP
8 Ld Flatpack
8 Ld Flatpack
8 Ld Flatpack
8 Ld Flatpack
Die
Die
Die
Die
Die
Die
8 Ld Flatpack
8 Ld Flatpack
8 Ld Flatpack
8 Ld SBDIP
8 Ld SBDIP
8 Ld SBDIP
Die
Die
8 Ld Flatpack
8 Ld Flatpack
8 Ld Flatpack
8 Ld SBDIP
8 Ld SBDIP
8 Ld SBDIP
Die
Die
8 Ld Flatpack
8 Ld Flatpack
8 Ld Flatpack
8 Ld SBDIP
8 Ld SBDIP
8 Ld SBDIP
Die
Die
8 Ld Flatpack
K8.A
K8.A
K8.A
K8.A
D8.3
D8.3
D8.3
K8.A
K8.A
K8.A
D8.3
D8.3
D8.3
K8.A
K8.A
K8.A
D8.3
D8.3
D8.3
PKG. DWG. #
D8.3
D8.3
D8.3
D8.3
K8.A
K8.A
K8.A
K8.A
FN7952 Rev 2.00
Feb 23, 2018
Page 2 of 17
ISL78840ASxH, ISL78841ASxH, ISL78843ASxH, ISL78845ASxH
Ordering Information
(Continued)
ORDERING NUMBER
(Note
1)
5962R0724904QXC
5962R0724904VXC
PART NUMBER
(Note
2)
ISL78845ASRHQF
ISL78845ASRHVF
ISL78845ASRHD/PROTO (Note
3)
5962R0724904QPC
5962R0724904VPC
NOTES:
1. These Pb-free Hermetic packaged products employ 100% Au plate - e4 termination finish, which is RoHS compliant and compatible with both SnPb
and Pb-free soldering operations.
2. Specifications for Rad Hard QML devices are controlled by the Defense Logistics Agency Land and Maritime (DLA). The SMD numbers listed in the
“Ordering Information” table must be used when ordering.
3. The /PROTO and /SAMPLE are not rated or certified for Total Ionizing Dose (TID) or Single Event Effect (SEE) immunity. These parts are intended for
engineering evaluation purposes only. The /PROTO parts meet the electrical limits and conditions across the temperature range specified in the
DLA SMD and are in the same form and fit as the qualified device. The /SAMPLE die is capable of meeting the electrical limits and conditions
specified in the DLA SMD at +25°C only. The /SAMPLE is a die and does not receive 100% screening across the temperature range to the DLA SMD
electrical limits. These part types do not come with a certificate of conformance because there is no radiation assurance testing and they are not
DLA qualified devices.
ISL78845ASRHQD
ISL78845ASRHVD
TEMP. RANGE
(°C)
-55 to +125
-55 to +125
-55 to +125
-55 to +125
-55 to +125
PACKAGE
(RoHS Compliant)
8 Ld Flatpack
8 Ld Flatpack
8 Ld SBDIP
8 Ld SBDIP
8 Ld SBDIP
PKG. DWG. #
K8.A
K8.A
D8.3
D8.3
D8.3
Pin Configurations
ISL78840ASEH, ISL78841ASEH, ISL78843ASEH, ISL78845ASEH
ISL78840ASRH, ISL78841ASRH, ISL78843ASRH, ISL78845ASRH
(8 LD FLATPACK)
TOP VIEW
COMP
FB
CS
RTCT
1
2
3
4
8
7
6
5
V
REF
V
DD
OUT
GND
CS
RTCT
3
4
6
5
ISL78840ASEH, ISL78841ASEH, ISL78843ASEH, ISL78845ASEH
ISL78840ASRH, ISL78841ASRH, ISL78843ASRH, ISL78845ASRH
(8 LD SBDIP)
TOP VIEW
COMP
FB
1
2
8
7
V
REF
V
DD
OUT
GND
FN7952 Rev 2.00
Feb 23, 2018
Page 3 of 17
ISL78840ASxH, ISL78841ASxH, ISL78843ASxH, ISL78845ASxH
Pin Descriptions
PIN NAME
RTCT
PIN NUMBER
4
DESCRIPTION
The oscillator timing control pin. The operational frequency and maximum duty cycle
are set by connecting a resistor, RT, between V
REF
and this pin and a timing
capacitor, CT, from this pin to GND. The oscillator produces a sawtooth waveform with
a programmable frequency range up to 2.0MHz. The charge time, t
C
, the discharge
time, t
D
, the RTCT oscillator frequency, f, and the maximum duty cycle, D
MAX
, can be
approximated from
Equations 1
through
4:
t
C
0.533
RT
CT
0.008
RT
–
3.83
-
t
D
–
RT
CT
In
--------------------------------------------
0.008
RT
–
1.71
f
=
1
tC
+
tD
D
=
t
C
f
(EQ. 1)
(EQ. 2)
(EQ. 3)
(EQ. 4)
The formulas have increased error at higher frequencies due to propagation delays.
Figure 7
may be used as a guideline in selecting the capacitor and resistor values
required for a given oscillator frequency for the ISL7884xASxH. The switching
frequency for the ISL78841ASxH and ISL78845ASxH will be half the RTCT oscillator
frequency.
COMP
1
COMP is the output of the error amplifier and the input of the PWM comparator. The
control loop frequency compensation network is connected between the COMP and
FB pins.
The output voltage feedback is connected to the inverting input of the error amplifier
through this pin. The noninverting input of the error amplifier is internally tied to a
reference voltage.
The current sense input to the PWM comparator. The range of the input signal is
nominally 0V to 1.0V and has an internal offset of 100mV.
GND is the power and small signal reference ground for all functions.
The drive output to the power switching device. It is a high current output capable of
driving the gate of a power MOSFET with peak currents of 1.0A. This GATE output is
actively held low when VDD is below the UVLO threshold.
V
DD
is the power connection for the device. The total supply current will depend on
the load applied to OUT. Total I
DD
current is the sum of the operating current and the
average output current. Knowing the operating frequency, f and the MOSFET gate
charge, Qg, the average output current can be calculated from
Equation 5:
I
OUT
=
Qg
f
(EQ. 5)
FB
2
CS
GND
OUT
3
5
6
V
DD
7
To optimize noise immunity, bypass V
DD
to GND with a ceramic capacitor as close to
the V
DD
and GND pins as possible.
V
REF
8
The 5.00V reference voltage output. +1.0/-1.5% tolerance over line, load and
operating temperature. The recommended bypass to GND cap is in the range 0.1µF
to 0.22µF. A typical value of 0.15µF can be used.
FN7952 Rev 2.00
Feb 23, 2018
Page 4 of 17
Functional Block Diagram
VDD
START/STOP
UV COMPARATOR
+
-
+
-
GND
2.5V
A
A = 0.5
VDD OK
ENABLE
V
REF
FAULT
-
+
VREF
5V
V
REF
4.65V
4.80V
PWM
COMPARATOR
CS
100mV
+
-
+
-
FB
+
-
ERROR
AMPLIFIER
2R
VF TOTAL = 1.15V
R
1.1V
CLAMP
ISL78845A
Q
T
Q
I
SL78841A,
ONLY
COMP
+
-
FN7952 Rev 2.00
Feb 23, 2018
Page 5 of 17
ISL78840ASxH, ISL78841ASxH, ISL78843ASxH, ISL78845ASxH
V
REF
UV COMPARATOR
OUT
S Q
36k
R Q
V
REF
100k
2.9V
1.0V
ON
OSCILLATOR
COMPARATOR
<10ns
-
+
8.4mA
ON
CLOCK
RESET
DOMINANT
150k
RTCT
FIGURE 1. BLOCK DIAGRAM
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