Datasheet

 2016-2019 Microchip Technology Inc. DS50002489D-page 27
RN4870/71
FIGURE 5-4: RN4871 REFERENCE CIRCUIT
FIGURE 5-5: RN4871U REFERENCE CIRCUIT
5.3 Power Drop Protection
To prevent any problems that may arise when the
power supply goes below 1.9V, a power-supply drop-
protection circuit is recommended. Essentially, this
circuit consists of a Reset IC which acts as an Open
Drain with a Delay =< 10 ms, and is triggered at 1.8V
power supply.
Figure 5-6 shows a recommended
power drop protection circuit.
RN4871
VBAT
14
P2_7
15
P1_6
6
P1_2
3
P1_3
4
P0_0
11
P3_6
9
P2_0
16
RST
10
UART_RX
7
UART_TX
8
P0_2
12
GND
13
NC
1
P1_7
5
GND
2
U1
B
LD1
GND
330
R1
GND
VCC
VCC
UART_TX UART_RX
P0_2
P1_2
P1_3
P1_7
P2_7
4.7k
R2
VCC
P0_2
3
2
1
STS2301
Q1
P0_0
P2_0
P1_6
P3_6
P1_2
P1_3
P2_7
P2_0
Configurable I/O
P2_0 MODE
Low
High
Test Mode
APP Mode
1
2
J1
GND
1
2
3
4
5
J2
GND
Power Input
Reverse Voltage ProtectionConfiguration Interface
VCC
UART_TX
UART_RX
UART Interface
LED Option
P0_2
10uF 6.3V X5R
C1
GND
GND
P0_0
P2_0
P3_6 P1_6
P1_7
1uF
C2
GND
RST
Reset Circuit
VDD
3
VOUT
1
VSS
2
MCP112
U2
GND
VCC
RN4871U
VBAT
11
BK_I
10
P2_7
15
P1_6
13
P1_2
2
P1_3
3
P0_0
8
P3_6
6
P2_0
16
RST
7
UART_RX
5
UART_TX
4
P0_2
9
GND
17
BT_RF
1
P1_7
14
GND
12
U1
B
LD1
GND
330
R1
GND
VCC
VCC
UART_TX
UART_RX
P0_2
P1_2
P1_3
P1_7 P2_7
4.7k
R2
VCC
P0_2
3
2
1
STS2301
Q1
P0_0
P2_0
P1_6
P3_6
P1_2
P1_3
P2_7
P2_0
Configurable I/O
P2_0 MODE
Low
High
Test Mode
APP Mode
1
2
J1
GND
1
2
3
4
5
J2
GND
Power Input
Reverse Voltage Protection
Configuration Interface
VCC
UART_TX
UART_RX
UART Interface
LED Option
P0_2
10uF 6.3V X5R
C1
GND
P0_0
P2_0
P3_6
P1_6
P1_7
GND
1uF
C2
GND
GND
C3 C4
ANT1
1nH
L1
GND
Antenna Matching
RST
VDD
3
VOUT
1
VSS
2
MCP112
U2
GND
VCC
Reset Circuit