Datasheet

FB
V
IN
V
CC
SW
RTN
ON TIMER
DRIVER
V
IN
BST
LEVEL
SHIFT
SD /
R
ON
2.5V
THERMAL
SHUTDOWN
0.725A
BUCK
SWITCH
CURRENT
SENSE
COMPLETE
R
CL
START
R
CL
COMPLETE
START
Ron
100 P
L1
C2
15 P
R3
3.01k
R4
1k
R2
100k
R1
200k
C4
0.01P
C3
0.1 P
12 -75V
10V
LM5007
UVLO
FB
R6
1
UVLO
REGULATION
COMPARATOR
OVER-VOLTAGE
COMPARATOR
2.875V
SD
SD
COMPLETE
START
300nS MIN OFF
TIMER
C1
1 P
8
6
5
3
4
1
2
7
7V SERIES
REGULATOR
CURRENT LIMIT
OFF TIMER
SHUTDOWN
C5
0.1 P,
100V
D1
Q
CLR
Q
SET
S
R
+
-
+
-
+
-
LM5007
SNVS252F –SEPTEMBER 2003–REVISED MARCH 2013 www.ti.com
Typical Application Circuit and Block Diagram
Pin Functions
Table 1. Pin Descriptions
Pin Name Description Application Information
1 SW Switching Node Power switching node. Connect to the LC output filter.
2 BST Boost Boot–strap capacitor input An external capacitor is required between the BST and the SW
pins. A 0.01uF ceramic capacitor is recommended. An internal
diode between Vcc and BST completes the Buck gate drive bias
network.
3 R
CL
Current Limit OFF time programming pin A resistor between this pin and RTN determines the variation of
Toff = 10
-5
/ (0.59 + (FB / 7.22 x 10
− 6
x R
CL
)) off time, along with the FB pin voltage, per cycle while in current
limit. The off time is preset to 17uS if FB =0V and decreases as
the FB pin voltage increases.
4 RTN Circuit Ground
5 FB Feedback Signal from Regulated Output This pin is connected to the inverting input of the internal
regulation comparator. The regulation threshold is 2.5V.
6 R
ON
On time set pin A resistor between this pin and Vin sets the switch on time as a
Ton = 1.42 x 10
-10
R
ON
/ Vin function of Vin. The minimum recommended on time is 300ns at
the maximum input voltage.
7 Vcc Output from the internal high voltage bias If an auxiliary voltage is available to raise the voltage on this pin,
regulator. V
CC
is nominally regulated to 7 V. above the regulation set point (7V), the internal series pass
regulator will shutdown, reducing the IC power dissipation. Do
not exceed 14V. This output provides gate drive power for the
internal Buck switch. An internal diode is provided between this
pin and the BST pin. A local 0.1uF decoupling capacitor is
recommended. Series pass regulator is current limited to 10mA.
8 Vin Input supply voltage Recommended operating range: 9V to 75V.
- EP Exposed PAD, underside of the WSON Internally bonded to the die substrate. Connect to GND potential
package option for low thermal impedance.
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