MAX5039EUA Maxim Integrated Products, MAX5039EUA Datasheet - Page 16

• Manufacturer Part Number: MAX5039EUA
• Description: Other Power Management V-Track Ctlr for PowerPC DSPs & ASICs
• Manufacturer: Maxim Integrated Products

Resistor tolerance error:
where:
If the nominal CORE set point is 1.6V, the ratio is
800mV/1600mV = 0.5. With 1% resistors, the resistor
error is:
Resistor temperature coefficient error:
A similar value applies when the (+) and (-) are
reversed in the above quotient. TCR is expressed in
parts per million. One-percent chip resistors are typi-
cally specified at ±100ppm while 0.1% resistors are
specified at ±25ppm.
Resistor Resolution Error: This error can be negligible
when R2 is split into two parts, a high-value 0.1% resistor
in series with a low-value 1% resistor to trim the final value.
MAX5039/MAX5040 reference error: ±2.0% by specifi-
cation.
Loop-gain error: This error is due to the finite system gain.
Table 1. Error Summation
Voltage-Tracking Controllers for
PowerPC, DSPs, and ASICs
16
Resistor Tolerance
Resistor TCR
(-40°C/+85°C)
Reference Voltage
Loop-Gain Error
Total = TOL
ERROR
ERROR
ERROR SOURCE
ERROR
______________________________________________________________________________________
ERROR
RES TCR
RESTOL
Ratio
RESTOL
-
GAIN
=
=
(%) = RES_TOL (%) x 2 x (1-Ratio)
100
(%) = ±1% x {2 x (1 - 0.5)} = ±1%
V
=
=
V
REGNOM
100
100
C REF




Ratio
_
+3.55/-3.75
(1% Res.)






AMOUNT
0 to -0.2
(
(
±0.55



 
1000
A
±1.0
±2.0
1
(%)
OL
1000
A
+
=
OL
R
R
11
2 1
×
×
[
[
V
REGNOM
×
+
×
800
−
Ratio
0 5
(
(
.
TCR
Ratio
TCR
0 5
mV
.
)
+
(0.1% Res.) (%)
)
1
+
+2.24/-2.44
×
×
AMOUNT
1
0 to -0.2
-1
±0.14
∆
±0.1
±2.0
∆
-1



T
T



)
)
]
]



 
-
1




A minimum but unspecified loop gain of 1000 yields a
-0.2% gain error. No positive gain error is possible.
Calculate the maximum and minimum regulator core
voltage set point as follows:
Set the CORE voltage set point (V
1.5016V and 1.665V and as close to the upper value
(1.665V) as possible.
Connect the midpoint of a voltage-divider between
CORE and GND to CORE_FB, as shown in Figure 10.
Set the midpoint voltage to 800mV for a maximum
CORE voltage set point of 1.665V.
Choose a value for R1 of 10kΩ.
Calculate R2 with the following equation:
Example:
Using a standard 9.09kΩ (±0.1%) resistor in series with
a 158Ω (1%) resistor yields negligible resolution error.
See the application circuit examples in Figures 9 and 10.
The MAX5039/MAX5040 provide a user-programmable
undervoltage lockout feature through the UVLO pin.
When using a resistor-divider, R7 and R8, from an input
voltage rail (V
mable UVLO feature allows V
before MAX5039/MAX5040 turn the system power sup-
plies on together. V
system power supplies and it can be the same as V
The UVLO pin also provides the system a way to turn
on/off the system power supplies (see the UVLO sec-
tion). Choose the UVLO trip point such that the mini-
mum V
CORESET
R
2
IN
CORESET
=
R
voltage exceeds the maximum UVLO rising
MAX
1
=
=
= 1.465V x 102.5% = 1.5016V
= ((3.3V + 5%) - 2V) + 2.5%
9 24855
IN
= 1.8V x 92.5% = 1.665V
= (3.465V - 2V) x 102.5%
R
.
= CORE
V
) to UVLO to GND, the user-program-
2
REGNOM
R
MIN
×
2
Programming UVLO Voltage
IN
V
C REF
=
k
is usually the input voltage to the
= I/O
_
Ω
MIN
V
-
1
REGNOM
V
C REF
MAX
=
- TOL = (1.8V - 5%) - 2.5%
_
IN



R
1 665
1
to get to a certain value
.
- ∆V
0 8
-
REGNOM
1
.
V
I/OC
V
-
0 8
.
+ TOL
V



10
) between
k
Ω
CC
.