参数资料
型号: TPS57040QDGQRQ1
厂商: TEXAS INSTRUMENTS INC
元件分类: 稳压器
英文描述: SWITCHING REGULATOR, 2500 kHz SWITCHING FREQ-MAX, PDSO10
封装: GREEN, PLASTIC, MSOP-10
文件页数: 8/51页
文件大小: 1871K
代理商: TPS57040QDGQRQ1
Vout
0.8V
R1 = R2
0.8 V
-
÷
è
EN
VIN
+
-
TPS57040-Q1
R 1
R 2
Ihys
I1
0.9 A
m
1.25 V
2.9 A
m
START
STOP
HYS
V
R1
I
-
=
ENA
START
ENA
1
V
R2
V
I
R1
=
-
+
EN
Ihys
VIN
+
-
TPS57040-Q1
R 1
R 2
VOUT
R3
I1
0.9 A
m
2.9 A
m
1.25 V
SLVSAP4A
– DECEMBER 2010 – REVISED APRIL 2011
DETAILED DESCRIPTION (continued)
(1)
Enable and Adjusting Undervoltage Lockout
The TPS57040-Q1 is disabled when the VIN pin voltage falls below 2.5 V. If an application requires a higher
undervoltage lockout (UVLO), use the EN pin as shown in Figure 28 to adjust the input voltage UVLO by using
the two external resistors. Though it is not necessary to use the UVLO adjust registers, for operation it is highly
recommended to provide consistent power up behavior. The EN pin has an internal pull-up current source, I1, of
0.9
μA that provides the default condition of the TPS57040-Q1 operating when the EN pin floats. Once the EN pin
voltage exceeds 1.25V, an additional 2.9
μA of hysteresis, Ihys, is added. This additional current facilitates input
voltage hysteresis. Use Equation 2 to set the external hysteresis for the input voltage. Use Equation 3 to set the
input start voltage.
Figure 28. Adjustable Undervoltage Lockout (UVLO)
(2)
(3)
Another technique to add input voltage hysteresis is shown in Figure 29. This method may be used, if the
resistance values are high from the previous method and a wider voltage hysteresis is needed. The resistor R3
sources additional hysteresis current into the EN pin.
Figure 29. Adding Additional Hysteresis
16
Copyright
2010–2011, Texas Instruments Incorporated
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