LM5035A-1 National Semiconductor, LM5035A-1 Datasheet - Page 5

• Manufacturer Part Number: LM5035A-1
• Description: PWM Controller
• Manufacturer: National Semiconductor

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TSSOP 20 PIN
LM5035A
10
11
12
13
14
15
5
6
7
8
9
LM5035A
LLP PIN
11
12
13
14
15
4
5
6
7
8
9
TSSOP 28 PIN
LM5035A-1
10
11
12
13
14
15
16
17
19
20
9
AGND
PGND
Name
DLY
RES
HO
CS
HB
HS
RT
SS
LO
5
Oscillator Frequency
Control and Sync Clock
Input
Analog Ground
Current Sense input for
current limit
Soft-start Input
Timing programming pin
for the LO and HO to SR1
and SR2 outputs.
Restart Timer
Boost voltage for the HO
driver
Switch node
High side gate drive
output.
Low side gate dfrive
output.
Power Ground
Description
Normally biased at 2V. An external
resistor connected between RT
and AGND sets the internal
oscillator frequency. The internal
oscillator can be synchronized to
an external clock with a frequency
higher than the free running
frequency set by the RT resistor.
Connect directly to Power Ground.
If CS exceeds 0.25V, the output
pulse will be terminated, entering
cycle-by-cycle current limit. An
internal switch holds CS low for
50ns after HO or LO switches high
to blank leading edge transients.
An internal 110µA current source
charges an external capacitor to
set the soft-start rate. During a
current limit restart sequence, the
internal current source is reduced
to 1.2µA to increase the delay
before retry.
An external resistor to ground sets
the timing for the non-overlap time
of HO to SR1 and LO to SR2.
If cycle-by-cycle current limit is
exceeded during any cycle, a 22 µA
current is sourced to the RES pin
capacitor.If the RES capacitor
voltage reaches 2.5V, the soft-start
capacitor will be fully discharged
and then released with a pull-up
current of 1.2µA. After the first
output pulse at LO (when SS
>COMP offset, typically 1V), the SS
pin charging current will revert to
110µA.
An external diode is required from
VCC to HB and an external
capacitor is required from HS to HB
to power the HO gate driver.
Connection common to the
transformer and both power
switches. Provides a return path for
the HO gate driver.
Output of the high side PWM gate
driver. Capable of sinking 2A peak
current
Output of the low side PWM gate
driver. Capable of sinking 2A peak
current.
Connect directly to Analog Ground.
Application Information
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