SLUSBZ9C Data sheet

SLUSBZ9C August 2015 – September 2016 BQ25120 , BQ25121

PRODUCTION DATA.

Package Options

Mechanical Data (Package|Pins)

YFP|25
- MXBG084M

Thermal pad, mechanical data (Package|Pins)

Orderable Information

10 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI's customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.

10.1 Application Information

A typical design is shown in Figure 35. This design uses the BQ25120 with external resistors for ILIM, IPRETERM, and ISET. These are not needed if these values are set with a host controller through I²C commands. This design also shows the TS resistors, which is also optional.

When powering up in default mode the battery voltage is the default for the part (4.2 V), the SYS output is the default (1.8 V). External resistors set the charge current to 40 mA, the termination current to 10% (4 mA), and the input current limit to 100 mA. If the I²C interface is used the part goes to the internal default settings until changed by the host.

10.2 Typical Application

BQ25120 BQ25121 Typ_App_Schematic_slusbz9.gif

Figure 35. Typical Application Circuit

10.2.1 Design Requirements

This application is for a low power system that has varying loads from less than 10 mA up to 300 mA. It must work with a valid adaptor or USB power input. Below are some of the key components that are needed in normal operation. For this example, the fast charge current is 50 mA, input current limit is 400 mA and the pre-charge and termination current is 10% of the fast charge current.

Supply voltage = 3.4 V to 20 V
Fast charge current is default to 10 mA with ISET pin shorted to ground. To program the fast charge current, connect an external resistor from ISET to ground.
Input current limit is default to 100 mA with ILIM pin shorted to ground. To program the input current limit, connect an external resistor from ILIM to ground.
Termination current threshold is default to 2 mA with IPRETERM pin shorted to ground. To program the input current limit, connect an external resistor from IPRETERM to ground.
A 2.2-µH inductor is needed between SW pin and SYS pin for PWM output.
TS- Battery temperature sense needs a NTC connected on TS pin.

10.2.2 Detailed Design Procedure

See Figure 35 for an example of the application diagram.

10.2.2.1 Default Settings

• Connect ISET, ILIM and IPRETERM pins to ground to program fast charge current to 10mA, input current limit to 100mA and pre-charge/termination current to 2 mA.
BAT_UVLO = 3 V.
VSYS = 1.8 V
LS/LDO is LS
VBREG = 4.2 V
VIN_DPM is enabled and VIN_DPM Threshold = 4.6 V.
Safety Timer = 3 hr
If the function is not needed, connect TS to the center tab of the resistor divider between V_IN and the ground. (pull up resistor = 14 kΩ, pull down resistor = 14.3 kΩ)

10.2.2.2 Choose the Correct Inductance and Capacitance

Refer to the Buck (PWM) Output section for the detailed procedure to determine the optimal inductance and capacitance for the buck output.

10.2.2.3 Calculations

10.2.2.3.1 Program the Fast Charge Current (ISET)

Equation 10. R_ISET = K_ISET/ICHG

K_ISET = 200 AΩ from the Specifications table

Equation 11. R_ISET = 200 AΩ / 0.05A = 4 kΩ

Select the closest standard value, which in this case is 4.99 kΩ. Connect this resistor between ISET pin and GND.

10.2.2.3.2 Program the Input Current Limit (ILIM)

Equation 12. R_ILIM = K_ILIM/I_{I_MAX}

K_ILIM = 200 AΩ from the Specifications table

Equation 13. R_ILIM = 200 AΩ / 0.4A = 500 Ω

Select the closest standard value, which in this case is 499 Ω. Connect this resistor between ILIM pin and GND.

10.2.2.3.3 Program the Pre-charge/termination Threshold (IPRETERM)

According to Table 3, the RIPRETERM is 4990 Ω for 10% termination threshold. Therefore, connect a 4.99 kΩ resistor between IPRETERM pin and GND.

10.2.2.3.4 TS Resistors (TS)

The voltage at TS is monitored to determine that the battery is at a safe temperature during charging. This device uses JEITA temperature profile which has four temperature thresholds. Refer to Specifications for the detailed thresholds number.

The TS circuit is shown in Figure 16. The resistor values can be calculated using Equation 1 and Equation 2.

10.2.3 Application Performance Curves

10.2.3.1 Charger Curves

Figure 36. Battery Connected to V_(BAT)

Figure 38. Entering DPPM Mode

Figure 40. Entering Battery Supplement Mode

Figure 42. Charger On/Off Using CD

Figure 37. Power Supply Connected to V_IN

Figure 39. Exiting DPPM Mode

Figure 41. Exiting Battery Supplement Mode

Figure 43. OVP Fault

10.2.3.2 SYS Output Curves

T_A = 25°C

V_SYS = 1.2 V

Figure 44. 1.2 V_SYS System Efficiency

T_A = 25°C

V_SYS = 1.8 V

Figure 46. 1.8 V_SYS System Efficiency

T_A = 25°C

V_SYS = 3.3 V

Figure 48. 3.3 V_SYS System Efficiency

T_A = 25°C

V_SYS = 1.5 V

Figure 50. 1.5 V_SYS Load Regulation

T_A = 25°C

V_SYS = 2.5 V

Figure 52. 2.5 V_SYS Load Regulation

T_A = 25°C

V_SYS = 1.2 V

Figure 54. 1.2 V_SYS Line Regulation

T_A = 25°C

V_SYS = 1.8 V

Figure 56. 1.8 V_SYS Line Regulation

T_A = 25°C

V_SYS = 3.3 V

Figure 58. 3.3 V_SYS Line Regulation

I_LOAD = 10 µA

Figure 60. Light Load Operation Showing SW

I_LOAD = 1 mA

Figure 62. Light Load Operation Showing SW

I_LOAD = 100 mA

Figure 64. Light Load Operation Showing SW

I_LOAD = 300 mA

Figure 66. Light Load Operation Showing SW

V_SYS = 1.8 V

Figure 68. 1.8 V_SYS Load Transient, 0 to 50 mA

V_SYS = 2.5 V

Figure 70. 2.5 V_SYS Load Transient, 0 to 50 mA

V_SYS = 1.2 V

Figure 72. 1.2 V_SYS Load Transient, 0 to 200 mA

V_SYS = 2.1 V

Figure 74. 2.1 V_SYS Load Transient, 0 to 200 mA

V_SYS = 3.3 V

Figure 76. 3.3 V_SYS Load Transient, 0 to 200 mA

Figure 78. Short Circuit and Recovery for SYS

T_A = 25°C

V_SYS = 1.5 V

Figure 45. 1.5 V_SYS System Efficiency

T_A = 25°C

V_SYS = 2.5 V

Figure 47. 2.5 V_SYS System Efficiency

T_A = 25°C

V_SYS = 1.2 V

Figure 49. 1.2 V_SYS Load Regulation

T_A = 25°C

V_SYS = 1.8 V

Figure 51. 1.8 V_SYS Load Regulation

T_A = 25°C

V_SYS = 3.3 V

Figure 53. 3.3 V_SYS Load Regulation

T_A = 25°C

V_SYS = 1.5 V

Figure 55. 1.5 V_SYS Line Regulation

T_A = 25°C

V_SYS = 2.1 V

Figure 57. 2.1 V_SYS Line Regulation

Figure 59. 1.8 V_SYS Switching Frequency vs Load Current

I_LOAD = 100 mA

Figure 61. Light Load Operation Showing SW

I_LOAD = 10 mA

Figure 63. Light Load Operation Showing SW

I_LOAD = 200 mA

Figure 65. Light Load Operation Showing SW

V_SYS = 1.2 V

Figure 67. 1.2 V_SYS Load Transient, 0 to 50 mA

V_SYS = 2.1 V

Figure 69. 2.1 V_SYS Load Transient, 0 to 50 mA

V_SYS = 3.3 V

Figure 71. 3.3 V_SYS Load Transient, 0 to 50 mA

V_SYS = 1.8 V

Figure 73. 1.8 V_SYS Load Transient, 0 to 200 mA

V_SYS = 2.5 V

Figure 75. 2.5 V_SYS Load Transient, 0 to 200 mA

Figure 77. Startup Showing SS on SYS in PWM Mode

10.2.3.3 Load Switch and LDO Curves

Figure 79. Short Circuit and Recovery for LS

V_SLSDO = 0.8 V

Figure 81. 0.8 V_LSLDO Load Transient, 0 to 10 mA

V_SLSDO = 1.8 V

Figure 83. 1.8 V_LSLDO Load Transient, 0 to 10 mA

V_SLSDO = 3.3 V

Figure 85. 3.3 V_LSLDO Load Transient, 0 to 10 mA

V_SLSDO = 1.2 V

Figure 87. 1.2 V_LSLDO Load Transient, 0 to 100 mA

V_SLSDO = 2.5 V

Figure 89. 2.5 V_LSLDO Load Transient, 0 to 100 mA

Figure 80. Startup Showing SS on LS/LDO Output

V_SLSDO = 1.2 V

Figure 82. 1.2 V_LSLDO Load Transient, 0 to 10 mA

V_SLSDO = 2.5 V

Figure 84. 2.5 V_LSLDO Load Transient, 0 to 10 mA

V_SLSDO = 0.8 V

Figure 86. 0.8 V_LSLDO Load Transient, 0 to 100 mA

V_SLSDO = 1.8 V

Figure 88. 1.8 V_LSLDO Load Transient, 0 to 100 mA

V_SLSDO = 3.3 V

Figure 90. 3.3 V_LSLDO Load Transient, 0 to 100 mA

10.2.3.4 LS/LDO Output Curves

Figure 91. Startup Showing SS on LS/LDO in LDO Mode

Figure 92. Short Circuit and Recovery for LDO

10.2.3.5 Timing Waveforms Curves

Figure 93. Show PG and INT Timing (VI_N Insertion)

Figure 95. PG Functions as Shifted MR Output

Wake1 = 500 ms

Wake2 = 1 s

Figure 97. Show MR Timing

RESET = 4 s

Figure 99. RESET Timing

RESET = 14 s

Figure 101. RESET Timing

Figure 94. Show PG and INT Timing (V_IN Removal)

Figure 96. PG Functions as Shifted MR Output

Wake1 = 50 ms

Wake2 = 1.5 s

Figure 98. Show MR Timing

RESET = 8 s

Figure 100. RESET Timing

Figure 102. RESET Timing and Enter Ship Mode