SP6656 Datasheet, PDF (3/17 Pages) Sipex Corporation – High Efficiency 400mA Synchronous Buck Regulator with Bit Programmable Output

PIN NUMBER
1
2
3
4
5
6
7
8
9
10
OVSI
PIN NAME
P_VIN
V_IN
OVSO
OVSI
EN
FB
V_OUT
GND
P_GND
LX
OVSO
PIN DESCRIPTION
DESCRIPTION
Input voltage power pin. Inductor charging current passes through this pin.
Internal supply voltage. Control circuitry powered from this pin.
Output Voltage Selection Output. OVSI = 1 PULLS THIS NODE TO
GND, OVSI = 0, this node is open.
Output Voltage Select Input. See table I for definition.
EN = 1, device is enabled. EN = 0, All internal circuitry is disabled and
power switches are opened.
External feedback network input connection. Connect a resistor from
FB to ground and FB to V_OUT to set the output voltage. This pin
regulates to the internal bandgap reference voltage of 0.8V.
Output voltage sense pin. Used by the timing circuit to set minimum on
and off times.
Internal ground pin. Control circuitry returns current to this pin.
Power ground pin. Synchronous rectifier current returns through this pin.
Inductor switching node. Inductor tied between this pin and the output
capacitor to create regulated output voltage.
Output Voltage
V_OUT
VO
0
Open
1
Short to GND
Table 1. Output Voltage Selection
Note: R_A =
R_I R_S
R_I +R_S
V
= 0.8 (R +R ) / R
OUT_LOW
IF
I
V_{OUT_HIGH} = 0.8 (R_A+R_F) /R_A
CF
R_F
22pF
FB
R_S ^OVSO
R_I
DRVON
VOLOW
T_ONOVER
MIN Ton
REF
+^Vos-^REF'
VOLOW
+
C
V_RAMP
-
FB ⁺
- ^FB'
RST
DRVON
OVR_I
V_IN
V_OUT
FUNCTIONAL DIAGRAM
P_VIN
Internal Supply
T_{ONOVER Min Ton}
Min T_ON = K_ON/(V_IN -V_OUT)
R
Q
_
S
Q
DRVON
DRIVER
M
1
+
ILIM/M
C
-
OVR_I
LX
D0
Ref
REF
UVLO
Block TSD
D1
ILIM/M
GND
BLANK
One-Shot
=100ns
T_OFF =
K_OFF/V_OUT
DRVON
BLANK
BLANK = T_BLANK(=100ns) or T_OFF = K_OFF/V_OUT
OVR_I
300mV
V_OUT ^{- +}
+
V_IN
C
-
UVLO
+
Zero_X
C
-
P_GND
BLON
Date: 7/9/04
SP6656 High Efficiency 400mA Synchronous Buck Regulator with Bit Programmable Output
3
© Copyright 2004 Sipex Corporation