LP3907SQ-JXQX NSC [National Semiconductor], LP3907SQ-JXQX Datasheet - Page 38

• Manufacturer Part Number: LP3907SQ-JXQX
• Description: Dual High-Current Step-Down DC/DC and Dual Linear Regulator with I2C Compatible Interface
• Manufacturer: NSC [National Semiconductor]

www.national.com
I
Both SDA and SCL terminals need to have pullup resistors
connected to VINLDO12 or to the power supply of the I
master. The values of the pull-up resistors (typ.
determined by the capacitance of the bus. Too large of a re-
sistor combined with a given bus capacitance will result in a
rise time that would violate the max. rise time specification. A
too small resistor will result in a contention with the pull-down
transistor on either slave(s) or master.
Operation without I
Operation of the LP3907 without the I
if the system can operate with default values for the LDO and
The I
The current value equals 0x60.
HIGH V
Additional information is provided when the IC is operated at
extremes of V
terms of the Junction temperature and, Buck output ripple
management.
JUNCTION TEMPERATURE
The maximum junction temperature T
IC package.
The following equations demonstrate junction temperature
determination, ambient temperature T
power must be controlled to keep T
T
Total IC power dissipation P
power dissipation of the four regulators plus a minor amount
for chip overhead. Chip overhead is Bias, TSD & LDO analog.
P
[Watts].
Power dissipation of LDO1
P
Power dissipation of LDO2
P
C
C
C
C
2
Factory programmable options
Enable delay for power on
SW1 ramp speed
SW2 ramp speed
J-MAX-OP
C Pullup Resistor
D-MAX
LDO1
LDO2
LDO1
LDO2
SW1
SW2
2
C Chip ID address is offered as a metal mask option.
= (V
= (V
= P
IN
Capacitor
HIGH-LOAD OPERATION
= T
INLDO1
INLDO2
LDO1
A-MAX
IN
+ P
and regulator loads. These are described in
- V
- Vout
+ (θ
LD02
OUTLDO1
2
C Interface
JA
LDO2
+ P
) [ °C/ Watt] * (P
) * Iout
BUCK1
) * Iout
D-MAX
Min Value
+ P
LDO1
is the sum of the individual
LDO2
0.47
0.47
10.0
10.0
J
below this maximum:
BUCK2
J-MAX-OP
2
C interface is possible
[V*A]
A-MAX
[V*A]
D-MAX
+ (0.0001A * V
and Total chip
of 125ºC of the
) [Watts]
∼
1.8kΩ) are
Unit
µF
µF
µF
µF
2
IN
C
)
LDO1 output capacitor
LDO2 output capacitor
SW1 output capacitor
SW2 output capacitor
38
Buck regulators. (Read below: Factory programmable op-
tions). The I
output values of the LDO and Buck converters.
Factory Programmable Options
The following options are EPROM programmed during final
test of the LP3907. The system designer that needs specific
options is advised to contact the local National Semiconduc-
tor sales office.
Power dissipation of Buck1
P
Vout
η
Power dissipation of Buck2
P
Vout
η
Where η is the efficiency for the specific condition taken from
efficiency graphs.
1
2
Buck1
Buck2
Current value
= efficiency of buck 1
= efficiency of Buck2
Description
Buck1
Buck2
= P
= P
* Iout
* Iout
IN
IN
code 010 (see Control 1 register section)
2
– P
– P
C-less system must rely on the correct default
Buck1
Buck2
OUT
OUT
* (1 -η
=
=
* (1 - η
1
Ceramic, 6.3V, X5R
Ceramic, 6.3V, X5R
Ceramic, 6.3V, X5R
Ceramic, 6.3V, X5R
) / η
8 mV/µs
8 mV/µs
2
) / η
1
2
Recommended Type
[V*A]
[V*A]