LP3942YQ NSC [National Semiconductor], LP3942YQ Datasheet - Page 7

• Manufacturer Part Number: LP3942YQ
• Description: The Dual RGB LED Controller with 1.5x/2x Charge Pump and SPI Interface
• Manufacturer: NSC [National Semiconductor]

Addr.
SPI Interface
LP3942 is compatible with SPI serial bus specification and it
operates as a write-only slave. One write cycle consists of 7
Address bits, 1 Read/Write (RW, always high) bit and 8 Data
bits. The Address and Data are transmitted MSB first.
SPI TIMING PARAMETERS
Charge Pump Mode Selection
Charge pump mode is controlled through the SPI interface. The mode selection is shown in the following tables.
If charge pump is disabled (CP_ON = 0) and LP3942 is active (NSTBY = 1), then charge pump output (P
connected externally to the same supply voltage (max 5.0V) which is used to drive LEDs with RGB1 or RGB2 outputs.
02’h
Control Bit
NSTBY
CP_ON
1.5x/2x
default
CTRL
Reg.
NSTBY
Symbol
[7]
0
1
2
3
4
5
6
7
8
Low Active Standby
Charge Pump Enable
Charge Pump Mode 1.5x/2x
CP_ON
Parameter
Cycle Time
Enable Lead Time
Enable Lag Time
Clock Low Time
Clock High Time
Data Setup Time
Data Hold Time
SS Inactive Time
[6]
0
Parameter
CC/SW2
[5]
SPI Timing Diagram
0
SPI Write Cycle
CC/SW1
7
[4]
0
The Slave Select signal SS must be low during the Cycle
transmission. SS resets the interface when high and it has to
be taken high between successive Cycles. Data is clocked in
on the rising edge of the SCK clock signal.
NSTBY = 0
NSTBY = 1
CP_ON = 0
CP_ON = 1
1.5x/2x = 0
1.5x/2x = 1
Min
80
35
35
15
10
40
5
5
State
Limit
1.5x/2x
[3]
0
Max
-
-
-
-
-
-
-
-
reserved
[2]
0
Units
ns
ns
ns
ns
ns
ns
ns
ns
LP3942 is disabled
LP3942 is active
Charge Pump is disabled
Charge Pump is active
1.5x mode, V
2x mode, V
reserved
Function
[1]
0
OUT
OUT
OUT
) pin must be
= 5V
20129205
= 4.5V
www.national.com
20129206
reserved
[0]
0