Datasheet

UVLO
OVLO
R1
R2
TP1
4
3
R3
LM25069
V
IN
R3 =
1.16V x R2
(V
OVH
± 1.16V)
R2 =
V
OVH
- V
OVL
20 PA
R4 =
1.17V x R1
(V
UVL
± 1.17V)
R1 =
V
UVH
- V
UVL
20 PA
UVLO
OVLO
R1
TP 1
4
3
R4
R2
R3
V
IN
LM25069
www.ti.com UVLO/OVLO Input Voltage Thresholds
Figure 6. UVLO, OVLO Inputs (Option B)
The four resistor values are calculated as follows:
Choose the upper and lower UVLO thresholds (V
UVH
) and (V
UVL
).
(11)
(12)
Choose the upper and lower OVLO threshold (V
OVH
) and (V
OVL
).
(13)
(14)
8.3 Option C
The minimum UVLO level is obtained by positioning the jumper at JMP1 on pins 1-2, and leaving R4
open, resulting in the configuration shown in Figure 7. Q1 is switched on when the voltage at VIN reaches
the POR threshold (≊2.6V). The OVLO thresholds are set by R2 and R3, and their values are calculated
using the procedure in Option B. The value for R1 is not critical, and can be as supplied.
Figure 7. Minimum UVLO Threshold, Adjustable OVLO
7
SNVA388D–February 2009–Revised May 2013 AN-1947 LM25069 Evaluation Board
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