ISL6142 Datasheet, PDF (14/23 Pages) Intersil Corporation – Negative Voltage Hot Plug Controller

ISL6142, ISL6152
Applications Information
GND
GND
Logic
Supply
R4
R10
R5
R6
ADC
Q2
R9
FAULT
DIS
IS_OUT
UV
V_DD
PWRGD
ISL6142
OV
CT V_EE IS-
IS+ SENSE GATE
DRAIN
C3
R7
R8
C1
R3
R2
C2
CL
RL
-48V IN
R1
Q1
FIGURE 29. TYPICAL APPLICATION WITH MINIMUM COMPONENTS
-48V OUT
Typical Values for a representative
system; which assumes:
43V to 71V supply range; 48 nominal; UV = 43V; OV = 71V
1A of typical current draw; 2.5 Amp Over-Current
100µF of load capacitance (CL); equivalent RL of 48Ω
(R = V/I = 48V/1A)
R1: 0.02Ω (1%)
R2: 10Ω (5%)
R3: 18kΩ (5%)
R4: 549kΩ (1%)
R5: 6.49kΩ (1%)
R6: 10kΩ (1%)
R7/R8: 400Ω (1%)
R9: 4.99KΩ (1%)
R10: 5.10KΩ (10%)
C1: 150nF (25V)
C2: 3.3nF (100V)
C3: 1500pF (25V)
Q1: IRF530 (100V, 17A, 0.11Ω)
Q2: N-Channel logic FET
Quick Guide to Choosing Component
Values
(See fig 29 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
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 comparator outputs will be in the
proper state signaling the supply is within its desired
operating range, allowing the GATE to turn on. The
equations below define the comparator thresholds for an
increasing (in magnitude) supply voltage.
V_UV
=
-^〈---^R-----⁴----+-----^R----⁵-----+-----^R----⁶---^〉-
(R₅ + R₆)
×
1.255
(EQ. 1)
V_OV = -^〈---^R-----⁴----+--₍--_R-^R----₆₅---₎--+-----^R----⁶---^〉- × 1.255
(EQ. 2)
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