LM5035MHX/NOPB National Semiconductor, LM5035MHX/NOPB Datasheet - Page 22

• Manufacturer Part Number: LM5035MHX/NOPB
• Description: IC PWM BCK BST FLYBK INV 20TSSOP
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LM5035MHX/NOPB

• Pwm Type: Voltage Mode
• Number Of Outputs: 1
• Frequency - Max: 1MHz
• Duty Cycle: 92%
• Voltage - Supply: 13 V ~ 105 V
• Buck: Yes
• Boost: Yes
• Flyback: Yes
• Inverting: Yes
• Doubler: No
• Divider: No
• Cuk: No
• Isolated: Yes
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 20-TSSOP Exposed Pad, 20-eTSSOP, 20-HTSSOP
• Frequency-max: 2MHz
• For Use With: LM5035EVAL - BOARD EVALUATION LM5035
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: LM5035MHX

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Once the controller has switched to standby mode, the out-
puts no longer switch but the VCC and REF regulators con-
tinue functioning and supply bias to the external circuitry. VCC
Figure 15 shows an application of the OVP comparator for
Remote Thermal Protection using a thermistor (or multiple
thermistors) which may be located near the main heat
sources of the power supply. The negative temperature co-
efficient (NTC) thermistor is nearly logarithmic, and in this
example a 100kΩ thermistor with the β material constant of
4500 kelvins changes to approximately 2kΩ at 130°C. Setting
R1 to one-third of this resistance (665Ω) establishes 130°C
as the desired trip point (for V
HICCUP MODE CURRENT LIMIT RESTART (RES)
The basic operation of the hiccup mode current limit restart is
described in the functional description. The delay time to
REF
= 5V). In a temperature band
FIGURE 14. Latched Load Over-Voltage Protection
FIGURE 15. Remote Thermal Protection
22
must fall below 6.2V or the UVLO pin must fall below 0.4V to
clear the OVP latch.
from 20°C below to 20°C above the OVP threshold, the volt-
age divider is nearly linear with 25mV per°C sensitivity.
R2 provides temperature hysteresis by raising the OVP com-
parator input by R2 x 23µA. For example, if a 22kΩ resistor is
selected for R2, then the OVP pin voltage will increase by
22kΩ x 23µA = 506mV. The NTC temperature must therefore
fall by 506mV / 25mV per°C = 20°C before the LM5035
switches from the standby mode to the normal mode.
restart is programmed with the selection of the RES pin ca-
pacitor C
RES
as illustrated in Figure 15.
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