ISL95870HRUZ-T Intersil, ISL95870HRUZ-T Datasheet - Page 18

• Manufacturer Part Number: ISL95870HRUZ-T
• Description: IC CTRLR PWM 1PHASE GPU 16UTQFN
• Manufacturer: Intersil

Specifications of ISL95870HRUZ-T

• Applications: Controller, GPU Core Power
• Voltage - Input: 3.3 V ~ 25 V
• Number Of Outputs: 1
• Voltage - Output: 0.5 V ~ 5 V
• Operating Temperature: -10°C ~ 100°C
• Mounting Type: *
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

connects the inverting input of the V
specific node among the string of R
resistors. All the resistors between that node and the
SREF pin serve as the feedback impedance R
V
node and the GND pin serve as the input impedance R
of the V
of the gain equation for the V
Where:
Equations 21, 22, 23 and 24 give the specific V
equations for the ISL95870B setpoint reference voltages.
The ISL95870B V
The ISL95870B V
The ISL95870B V
The ISL95870B V
The V
closure of internal switch SW0 that configures the V
amplifier as a unity-gain voltage follower for the 0.5V
voltage reference V
use the naming convention V
second, third, or fourth setpoint reference voltage
where:
For given four user selected reference voltages V
the programmed resistors R
R
initial value to R
V
V
V
V
V
SET
SET2
SET3
SET4
SETX
SET1
SET4
- V
- V
- V
- V
VID1
that appears at the SREF pin
1
1
0
0
REF
SETx
SET1
OUT1
amplifier. Likewise, all the resistors between that
SET1
VID STATE
=
=
are designed in the following way. First, assign an
=
=
=
SET
TABLE 2. ISL95870B VID TRUTH TABLE
V
V
V
V
V
is the 0.5V internal reference of the IC
REF
REF
REF
REF
REF
is the resulting setpoint reference voltage
is fixed at 0.5V because it corresponds to the
< V
< V
amplifier. Equation 20 gives the general form
⋅
⋅
⋅
⋅
VID0
⎛
⎜
⎝
⎛
⎜
⎝
⎛
⎜
⎝
⎛
⎜
⎝
SET2
OUT2
1
1
1
1
SET4
1
0
1
0
+
+
+
SET1
SET2
SET3
SET4
+
-------------------------------------------------------------------- -
R
R
------------------------------------------- -
R
--------- -
R
R
-------------------------------------------------------------------- -
R
REF
SET2
SET1
SET3
IN
SET1
F
< V
< V
of approximately 100kΩ then
⎞
⎟
⎠
. The setpoint reference voltages
setpoint is written as Equation 21:
setpoint is written as Equation 22:
setpoint is written as Equation 23:
setpoint is written as Equation 24:
SET3
+
+
+
OUT3
CLOSE
+
18
R
R
R
R
SW0
SW1
SW2
SW3
R
R
SET1
SET3
SET2
SET4
SET2
SET4
SET1
SET(x)
SET
< V
< V
⎞
⎟
⎠
+
ISL95870, ISL95870A, ISL95870B
+
, R
amplifier:
R
R
OUT4
SET4
SET
SET4
where (x) is the first,
SET3
RESULT
SET2
SET
V
V
V
V
V
SREF
SET1
SET2
SET3
SET4
programming
⎞
⎟
⎠
Thus,
⎞
⎟
⎠
amplifier to a
, R
SET3
F
of the
SET
V
V
V
V
(EQ. 24)
(EQ. 20)
V
(EQ. 21)
(EQ. 22)
(EQ. 23)
and
OUT1
OUT2
OUT3
OUT4
SETx
OUT
SET
IN
,
calculate R
26, and 27 respectively.
The sum of all the programming resistors should be
approximately 300kΩ, as shown in Equation 28,
otherwise adjust the value of R
calculations.
FIGURE 11. ISL95870B VOLTAGE PROGRAMMING
If the output voltage is in the range of 0.5V to 1.5V, the
external resistor-divider is not necessary. The output
voltage is equal to one of the reference voltages
depending on the status of VID1 and VID0. The external
resistor divider consisting of R
user to program the output voltage in the range of 1.5V
to 5V. The relation between the output voltage and the
reference is given in Equation 29:
In this case, the four output voltages are equal to each of
the corresponding reference voltages multiplying the
factor k.
R
R
R
V
V
OUTx
SET1
SET2
SET3
OUT
R
V
SET1
OUT
=
=
=
=
=
+
V
R
------------------------------------------------------------------------------------------ -
R
--------------------------------------------------------------------------------------------- -
R
---------------------------------------------------------------------- -
V
R
SREF
R
SETx
SET4
SET4
SET4
FB
SET1,
SET2
CIRCUIT
⋅
k ⋅
⋅
⋅
⋅
R
--------------------------------- -
V
V
(
+
V
V
V
V
R
SET4
SET4
FB
R
SET4
REF
SET2
SET3
SREF
SET2
SET0
SET1
SET2
R
SET3
+
OFS
FB
R
⋅
⋅
⋅
OFS
–
(
V
(
⋅
V
V
and R
+
V
SET2
V
SET2
SET3
SET3
R
SET3
SET4
=
V
SET3
–
–
)
FB
SREF
SET4
V
V
≅
REF
SET2
and R
300kΩ
−
+
using Equations 25,
k ⋅
EA
SW0
SW1
SW2
SW3
)
and repeat the
V
)
SET
OFS
+
−
V
December 22, 2009
V
allows the
COMP
REF
0.5V
(EQ. 25)
(EQ. 26)
(EQ. 27)
(EQ. 29)
(EQ. 30)
(EQ. 28)
FN6899.0