LM5116MH/NOPB National Semiconductor, LM5116MH/NOPB Datasheet - Page 21

• Manufacturer Part Number: LM5116MH/NOPB
• Description: IC CTRLR SYNCH BUCK 20-TSSOP
• Manufacturer: National Semiconductor
• Series: PowerWise®r
• Type: Step-Down (Buck)r

Specifications of LM5116MH/NOPB

• Internal Switch(s): No
• Synchronous Rectifier: Yes
• Number Of Outputs: 1
• Voltage - Output: 1.22 ~ 80 V
• Current - Output: 20A
• Frequency - Switching: 50kHz ~ 1MHz
• Voltage - Input: 6 ~ 100 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 20-TSSOP Exposed Pad, 20-eTSSOP, 20-HTSSOP
• Dc To Dc Converter Type: Synchronous Buck Controller
• Pin Count: 20
• Input Voltage: 6 to 100V
• Output Voltage: 1.215 to 80V
• Output Current: 3.5A
• Package Type: TSSOP EP
• Mounting: Surface Mount
• Operating Temperature Classification: Automotive
• Operating Temperature (min): -40C
• Operating Temperature (max): 125C
• For Use With: LM5116-12EVAL - BOARD EVALUATION FOR LM5116-12LM5116EVAL - BOARD EVALUATION LM5116
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Lead Free Status / Rohs Status: Compliant
• Other names: LM5116MH

The regulator has an exposed thermal pad to aid power dis-
sipation. Selecting MOSFETs with exposed pads will aid the
power dissipation of these devices. Careful attention to R
(ON)
a MOSFET with low gate capacitance will result in lower
switching losses.
Comprehensive Equations
CURRENT SENSE RESISTOR AND RAMP CAPACITOR
T = 1 / f
current at current limit.
General Method for V
General Method for 5V < V
Best Performance Method:
This minimizes the current limit deviation due to changes in
line voltage, while maintaining near optimal slope compen-
sation.
Calculate optimal slope current, I
example, at V
at high temperature should be observed. Also, at 250 kHz,
SW
, g
m
= 5µA/V, A = 10V/V. I
OUT
= 7.5V, I
OUT
< 5V:
OS
OUT
= 25µA.
< 7.5V:
OS
OUT
= (V
is the maximum output
OUT
/ 3) x 10µA/V. For
DS
21
Calculate V
For V
For V
made with a simple charge pump from the LO gate output.
Install a resistor from the RAMP pin to the negative VCC.
If a large variation is expected in VCC, say for V
Zener regulator may be added to supply a constant voltage
for R
RAMP
OUT
OUT
FIGURE 15. R
FIGURE 14. R
> 7.5V, install a resistor from the RAMP pin to VCC.
.
< 7.5V, a negative VCC is required. This can be
RAMP
at the nominal input voltage.
RAMP
RAMP
to -VCC for V
to VCC for V
30007573
30007575
OUT
OUT
> 7.5V
< 7.5V
www.national.com
IN
< 11V, a