LT3582 LINER [Linear Technology], LT3582 Datasheet - Page 17

• Manufacturer Part Number: LT3582
• Description: I2C Programmable Boost and Single Inductor Inverting DC/DC Converters with OTP
• Manufacturer: LINER [Linear Technology]

APPLICATIONS INFORMATION
Since the LT3582 series won’t power-down until both
outputs are discharged (when power-down sequencing
is enabled), make sure V
This is not a problem in most topologies. However, read
the section Output Disconnect Operating Limits for ad-
ditional information.
Confi guration Lockout (LOCK bit)
After a desired confi guration is programmed into OTP, the
LOCK bit can be set to prohibit subsequent changes to the
confi guration. The LT3582-5 and LT3582-12 are precon-
fi gured with the LOCK bit set to a logic “1” which:
The LOCK OTP bit is set by programming a logic “1” into
bit 6 of OTP2. Regardless of the RSEL2 setting, I
of the LOCK bit always indicate the LOCKed or unlocked
state of the OTP memory.
OTP Programming (LT3582 only)
The LT3582 contains One Time Programmable non-vola-
tile memory to permanently store the chip confi guration.
Before programming, it’s recommended to set the SWOFF
bit to disable switching activity and prevent unexpected
chip behavior while the confi guration is being changed.
Programming involves the transfer of information from
the REG bytes to the OTP bytes. Therefore, valid data
must fi rst be written to the desired REG bytes. After the
REG bytes are written, they are selected by setting the
corresponding RSEL bits in the CMDR. This forces the chip
into the desired confi guration and selects those bytes for
• Forces the chip to use the OTP confi guration
• Forces all I
• Prohibits any further programming of the OTP
only.
OTP data.
memory. Any further attempts to program OTP leaves
the OTP memory unchanged and sets the FAULT bit
in the CMDR.
2
C reads from addresses 0-2 to return
OUTP
& V
OUTN
can be grounded.
2
C reads
programming to OTP. After 15V has been applied to V
the WOTP bit is set in the CMDR to start the programming.
Finally, the WOTP bit is cleared to fi nish the programming.
An example programming algorithm is given below.
OTP programming draws about 3-6mA per bit from the
V
ously (up to ~138mA), but it is recommended that one byte
is programmed at a time to reduce noise on V
by the sudden change in current. A 1-10μF V
capacitor is also recommended to prevent voltage droop
after programming begins. Also, avoid hot-plugging V
which results in very fast voltage ramp rates and can lead
to excessive voltage on the V
Example OTP Programming Algorithm:
PP
LT3582/LT3582-5/LT3582-12
1. Apply 15V to the V
2. Write 50h to the CMDR. This disables the power
3. Write desired data to REG0-REG2.
4. Write 11h to the CMDR. This selects REG0 for pro-
5. Write 91h to the CMDR. This programs the REG0
6. Write 11h to the CMDR. This command can be sent
7. Read the CMDR and verify that the FAULT bit is
8. Repeat steps 4-7 for the remaining bytes that need
9. Write 10h to the CMDR. This selects the OTP data
pin. It is possible to program all 23 bits simultane-
time before step 5.
switches during programming by setting the SWOFF
bit in the CMDR. This also clears the FAULT bit.
gramming while keeping the switches off.
data to OTP0.
immediately after step 5. This stops the program-
ming.
not set.
programming.
for read verifi cation.
PP
pin. This can be done at any
PP
pin.
PP
PP
17
caused
bypass
3582512f
PP
PP
,