LTC1436AIGN-PLL#TR Linear Technology, LTC1436AIGN-PLL#TR Datasheet - Page 15

• Manufacturer Part Number: LTC1436AIGN-PLL#TR
• Description: IC REG SW SYNC STEPDWN LN 24SSOP
• Manufacturer: Linear Technology
• Type: Step-Down (Buck)r

Specifications of LTC1436AIGN-PLL#TR

• Internal Switch(s): No
• Synchronous Rectifier: Yes
• Number Of Outputs: 1
• Voltage - Output: 1.19 ~ 9 V
• Current - Output: 50mA
• Frequency - Switching: 125kHz ~ 240kHz
• Voltage - Input: 3.5 ~ 30 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 24-SSOP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Power - Output: -
• Other names: LTC1436AIGN-PLLTR

APPLICATIONS
include Sanyo OS-CON, Nichicon PL series and Sprague
593D and 595D series. Consult the manufacturer for other
specific recommendations.
INTV
An internal P-channel low dropout regulator produces the
5V supply that powers the drivers and internal circuitry
within the LTC1436A/LTC1437A. The INTV
supply up to 15mA and must be bypassed to ground with
a minimum of 2.2µF tantalum or low ESR electrolytic.
Good bypassing is necessary to supply the high transient
currents required by the MOSFET gate drivers.
High input voltage applications, in which large MOSFETs
are being driven at high frequencies, may cause the
maximum junction temperature rating for the LTC1436A/
LTC1437A to be exceeded. The IC supply current is
dominated by the gate charge supply current when not
using an output derived EXTV
is dependent on operating frequency as discussed in the
Efficiency Considerations section. The junction tempera-
ture can be estimated by using the equations given in Note
1 of the Electrical Characteristics. For example, the
LTC1437A is limited to less than 19mA from a 30V supply:
To prevent maximum junction temperature from being
exceeded, the input supply current must be checked when
operating in continuous mode at maximum V
EXTV
The LTC1436A/LTC1437A contain an internal P-channel
MOSFET switch connected between the EXTV
INTV
power whenever the EXTV
remains closed until EXTV
allows the MOSFET driver and control power to be derived
from the output during normal operation (4.8V < V
9V) and from the internal regulator when the output is out
of regulation (start-up, short circuit). Do not apply greater
than 10V to the EXTV
Significant efficiency gains can be realized by powering
INTV
from the driver and control currents will be scaled by a
T
J
CC
CC
CC
CC
= 70 C + 19mA
Regulator
pins. The switch closes and supplies the INTV
from the output, since the V
Connection
°
(
U
CC
)( )
30
pin and ensure that EXTV
INFORMATION
U
V
CC
CC
(
95
CC
drops below 4.5V. This
pin is above 4.8V, and
°
source. The gate charge
C W
/
W
IN
)
=
current resulting
124
CC
IN
°
C
U
.
CC
pin can
CC
< V
OUT
and
IN
CC
<
.
factor of Duty Cycle
supply means connecting the EXTV
However, for 3.3V and other lower voltage regulators,
additional circuitry is required to derive INTV
from the output.
The following list summarizes the four possible connec-
tions for EXTV
1. EXTV
2. EXTV
3. EXTV
4. EXTV
to be powered from the internal 5V regulator resulting
in an efficiency penalty of up to 10% at high input
voltages.
connection for a 5V regulator and provides the highest
efficiency.
For 3.3V and other low voltage regulators, efficiency
gains can still be realized by connecting EXTV
output-derived voltage which has been boosted to
greater than 4.8V. This can be done with either the
inductive boost winding as shown in Figure 4a or the
capacitive charge pump shown in Figure 4b. The charge
pump has the advantage of simple magnetics.
supply is available in the 5V to 10V range (EXTV
V
compatible with the MOSFET gate drive requirements.
When driving standard threshold MOSFETs, the exter-
nal supply must always be present during operation to
prevent MOSFET failure due to insufficient gate drive.
Figure 4a. Secondary Output Loop and EXTV
R6
R5
OPTIONAL EXTV
CONNECTION
5V ≤ V
IN
), it may be used to power EXTV
SFB
SGND
EXTV
LTC1436A
LTC1437A
CC
CC
CC
SEC
CC
CC
≤ 9V
left open (or grounded). This will cause INTV
connected to an output-derived boost network.
connected directly to V
connected to an external supply. If an external
LTC1436A-PLL/LTC1437A
PGND
TGS
CC
TGL
V
SW
BG
CC
IN
:
C
IN
+
/
Efficiency. For 5V regulators this
N-CH
N-CH
N-CH
V
IN
OUT
1N4148
CC
1:N
T1
. This is the normal
pin directly to V
CC
LTC1436A
, providing it is
CC
R
SENSE
Connection
V
SEC
CC
CC
+
+
15
power
14367afb
to an
1436 F04a
OUT
CC
1µF
C
OUT
V
CC
OUT
<
.