ISL6140/41EVAL1Z Intersil, ISL6140/41EVAL1Z Datasheet - Page 11

• Manufacturer Part Number: ISL6140/41EVAL1Z
• Description: EVAL BOARD 1 FOR ISL6140/41
• Manufacturer: Intersil

Specifications of ISL6140/41EVAL1Z

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Applications Information
Typical Values for a representative system; which
assumes:
• 43V to 71V supply range; 48 nominal; UV = 43V;
• 1Amp of typical current draw; 2.5 Amp Over-Current
• 100µF of load capacitance (CL); equivalent RL of 48Ω
R1: 0.02Ω (1%)
R2: 10Ω (5%)
R3: 18kΩ (5%)
R4: 549kΩ (1%)
R5: 6.49kΩ (1%)
R6: 10kΩ (1%)
C1: 150nF (25V)
C2: 3.3nF (100V)
Q1: IRF530 (100V, 17A, 0.11Ω)
Quick Guide to Choosing Component
Values
(See fig 23 for reference)
This section will describe the minimum components needed
for a typical application, and will show how to select
component values. (Note that “typical” values may only be
good for this application; the user may have to select
alternate component values to optimize performance for
other applications). Each block will then have more detailed
explanation of how the device works, and alternatives.
R4, R5, R6 - together set the Under-Voltage (UV) and Over-
Voltage (OV) trip points. When the power supply ramps up
and down, these trip points (and their hysteresis) will
determine when the GATE is allowed to turn on and off (UV
and OV do not control the PWRGD / PWRGD output). The
OV = 71V
(R = V/I = 48V/1A)
-48V IN
GND
11
FIGURE 23. TYPICAL APPLICATION WITH MINIMUM COMPONENTS
R4
R5
R6
UV
OV
V
EE
ISL6141, ISL6151
R1
SENSE
ISL6141
V
C1
DD
GATE
Q1
R2
input power supply is divided down such that when the
voltage on the OV pin is below its threshold and the UV pin is
above its threshold their comparators will be in the proper
state signaling the supply is within its desired range, allowing
the GATE to turn on. The equations below define the
comparator thresholds for an increasing (in magnitude)
supply voltage.
The values of R4 = 549K, R5 = 6.49K, and R6 = 10K shown
in figure 23 set the Under-Voltage turn-on threshold to 43V,
and the Over-Voltage turn off threshold to 71V. The Under-
Voltage (UV) comparator has a hysteresis of 135mV (4.6V of
hysteresis on the supply) which correlates to a 38.4V turn off
voltage. The Over-Voltage comparator has a 25mV
hysteresis which translates to a turn on voltage (supply
decreasing) of approximately 69.6V.
Q1 - is the FET that connects the input supply voltage to the
output load, when properly enabled. It needs to be selected
based on several criteria:
• Maximum voltage expected on the input supply (including
• Maximum current and power dissipation expected during
• Power dissipation and/or safe-operating-area
• Other considerations include the GATE voltage threshold
R3
V
V
transients) as well as transients on the output side.
normal operation, usually at a level just below the current
limit threshold.
considerations during current limiting and single retry
events.
which affects the r
voltage drop across the FET during normal operation),
and the maximum GATE voltage allowed (the ICs GATE
output is clamped to ~14V).
OV
UV
=
=
PWRGD
C2
DRAIN
---------------------------------------- -
---------------------------------------- -
〈
〈
R
R
(
4
4
R
+
+
5
(
R
R
R
+
6
5
5
R
)
+
+
6
R
R
)
DS(ON)
6
6
〉
〉
×
×
1.255
1.255
-48V OUT
RL
(which in turn, affects the
(LOAD)
CL
(EQ. 2)
(EQ. 1)