How the Sandstrom 18W PD AC Charger Supports USB Power Delivery for Charging Your Apple iPhone or iPad

The Sandstrom 18W PD AC Charger can be useful for keeping your Apple iPhone or iPad charged. The single USB Type-C output port on the charger supports USB Power Delivery technology to offer fast charging up to 18W for recent Apple iPhone's and iPad's that can use USB Power Delivery like the Apple iPhone XS, iPhone XS Max, iPhone XR, iPhone X, 10.5-inch iPad Pro and 12.9-inch iPad Pro over the Lightning connector or even the Apple 11-inch iPad Pro (2018) over USB Type-C.

The Sandstrom 18W PD AC Charger ships with its own 1 m USB Type-C to Lightning cable and states on its box to support the common USB Power Delivery profiles of 15 watts (5 volts @ 3 amps), 18 watts (9 volts @ 2 amps) and 18 watts (12 volts @ 1.5 amps) for charging out.

To observe the power capabilities of the Sandstrom 18W PD AC Charger, we used the USB Power Test App from Granite River Labs with the Granite River Labs USB Power Delivery Compliance C2 Tester to generate the following test results.

The USB Power Test App first negotiates a power contract for every PDO supported by the Sandstrom charger, and increases the load gradually to find the threshold where over current protection (OCP) kicks in and voltage and current start to drop for safety reasons.

The USB Power Test App reports out all the PDO's supported by the Sandstrom charger and their OCP thresholds. Note the PDO's listed are also showing Augmented PDO's (APDO's) even though the charger's box and casing only state fixed PDO's, and also this charger caters for Apple devices which do not support APDO's. OCP thresholds for the APDO's are also very low for both PDO #4 and PDO #5.

PDO	OCP
PDO#1 Fixed: 5V 3A	3.56
PDO#2 Fixed: 9V 2A	2.37
PDO#3 Fixed: 12V 1.5A	1.73
PDO#4 PPS: (3.3~5.9)V 3A	2.63
PDO#5 PPS: (3.3~11)V 2A	2.02

The USB Power Test App takes this data to produce an I-V curve which graphically shows the relationship between voltage and current for each PDO. Interestingly, unlike other chargers that support PPS (Programmable Power Supply), no current fold-back behavior is observed for all the PDO's except for PDO #5. We can see the voltage immediately shuts off once the current crosses the OCP threshold rather than curving down.  

The USB Power Test App can also use the Granite River Labs USB Power Delivery Compliance C2 Tester integrated with the GW Instek APS-7100 programmable AC power supply to compare the charger's power output vs power input so that power efficiency can be measured and compared to regulatory limits from United States of Energy (DOE) Level VI or European Union's CoC Tier 2 requirements. We can repeat the power efficiency tests for different PDO's, current load conditions, and different AC input ranges, allowing us to get a complete picture of power efficiency ranges across all different usage scenarios.

Using the USB Power Test App and FLIR thermal imaging tools, we measured the heat emitted by the Sandstrom charger as seen in the following temperature graph for the highest 12V, 1.5A fixed PDO, which recorded max temperature of around 62.2 degree Celsius.

Using the USB Power Delivery Compliance C2 Tester from Granite River Labs to run just a subset of the full USB Power Delivery compliance test suite, we can confirm that the Sandstrom charger supports the following fixed PDO's- 15 watts (5 volts @ 3 amps), 18 watts (9 volts @ 2 amps) and 18 watts (12 volts @ 1.5 amps) as well as APDO's of 3.3~5.9 volts @ 3 amps and 3.3~11 volts @ 2 amps. Note some compliance failures were also observed for this charger.

Source Capabilities

Parameter	GetCapabilities
Src_PDO_Supply_Type #1	Fixed
Src_PDO_Voltage #1	5000
Src_PDO_Max_Current #1	3000
Src_PDO_Supply_Type #2	Fixed
Src_PDO_Voltage #2	9000
Src_PDO_Max_Current #2	2000
Src_PDO_Supply_Type #3	Fixed
Src_PDO_Voltage #3	12000
Src_PDO_Max_Current #3	1500
Src_PDO_Supply_Type #4	Augmented_PDO
Src_PDO_Max_Voltage #4	5900
Src_PDO_Min_Voltage #4	3300
Src_PDO_Max_Current #4	3000
Src_PDO_Supply_Type #5	Augmented_PDO
Src_PDO_Max_Voltage #5	11000
Src_PDO_Min_Voltage #5	3300
Src_PDO_Max_Current #5	2000

Power Delivery 3.0 Tests- Result Summary

Sl No	Test ID	Test Name	Test Result
1	TD.PD.LL3.E1	TD.PD.LL3.E1 GoodCRC Specification Revision compatibility	PASS
2	TD.PD.LL3.E2	TD.PD.LL3.E2 Retransmission	PASS
4	TD.PD.SRC3.E1	TD.PD.SRC3.E1 Source Capability Fields Checks	PASS
5	TD.PD.SRC3.E2	TD.PD.SRC3.E2 Accept Fields Checks	PASS
6	TD.PD.SRC3.E3	TD.PD.SRC3.E3 PSRDY Fields Checks	PASS
7	TD.PD.SRC3.E4	TD.PD.SRC3.E4 Specification Revision Check after Contract	PASS
8	TD.PD.SRC3.E5	TD.PD.SRC3.E5 Source Capabilities Extended sent timely	PASS
9	TD.PD.SRC3.E6	TD.PD.SRC3.E6 Source Capabilities Extended Fields Checks	PASS
10	TD.PD.SRC3.E7	TD.PD.SRC3.E7 Battery Status sent Timely	PASS
11	TD.PD.SRC3.E8	TD.PD.SRC3.E8 Battery Status Fields Checks	PASS
12	TD.PD.SRC3.E9	TD.PD.SRC3.E9 Battery Status Fields Checks Invalid Battery reference	PASS
13	TD.PD.SRC3.E10	TD.PD.SRC3.E10 Unrecognized Message Received in Ready State	PASS
14	TD.PD.SRC3.E11	TD.PD.SRC3.E11 Get Status Fields Checks	PASS
15	TD.PD.SRC3.E12	TD.PD.SRC3.E12 Get Battery Status Fields Checks	PASS
16	TD.PD.SRC3.E13	TD.PD.SRC3.E13 Status sent timely	PASS
17	TD.PD.SRC3.E14	TD.PD.SRC3.E14 Status Fields Checks	PASS
18	TD.PD.SRC3.E15	TD.PD.SRC3.E15 Battery Capabilities sent timely	PASS
19	TD.PD.SRC3.E16	TD.PD.SRC3.E16 Battery Capabilities Fields Checks	PASS
20	TD.PD.SRC3.E17	TD.PD.SRC3.E17 Battery Capabilities Fields Checks Invalid Battery Reference	PASS
21	TD.PD.SRC3.E18	TD.PD.SRC3.E18 Manufacturer Info Sent Timely	PASS
22	TD.PD.SRC3.E19	TD.PD.SRC3.E19 Manufacturer Info Fields Checks	PASS
23	TD.PD.SRC3.E20	TD.PD.SRC3.E20 Manufacturer Info Fields Checks Invalid Manufacturer Info Target	PASS
24	TD.PD.SRC3.E21	TD.PD.SRC3.E21 Manufacturer Info Fields Checks Invalid Manufacturer Info Ref	PASS
27	TD.PD.SRC3.E24	TD.PD.SRC3.E24 Unexpected Message Received in Ready State	PASS
28	TD.PD.SRC3.E25	TD.PD.SRC3.E25 Receiving chunked extended message	PASS
29	TD.PD.SRC3.E26	TD.PD.SRC3.E26 Soft Reset sent regardless of Rp value	PASS
30	TD.PD.SRC3.E27	TD.PD.SRC3.E27 PPS Status Sent Timely	PASS
31	TD.PD.SRC3.E28	TD.PD.SRC3.E28 PPS Status Fields Check	PASS
32	TD.PD.SRC3.E29	TD.PD.SRC3.E29 SourcePPSCommTimer Deadline	PASS
33	TD.PD.SRC3.E30	TD.PD.SRC3.E30 SourcePPSCommTimer Timeout	PASS
34	TD.PD.SRC3.E31	TD.PD.SRC3.E31 SourcePPSCommTimer Stopped	PASS
36	TD.PD.SRC3.E33	TD.PD.SRC3.E33 Country Codes Sent Timely	PASS
37	TD.PD.SRC3.E34	TD.PD.SRC3.E34 Country Codes Fields Checks	PASS
38	TD.PD.SRC3.E35	TD.PD.SRC3.E35 Country Info Sent Timely	PASS
39	TD.PD.SRC3.E36	TD.PD.SRC3.E36 Country Info Fields Checks	PASS
40	TD.PD.VDM3.E1	TD.PD.VDM3.E1 Fields Checks Discover Identity	PASS
42	TD.PD.VNDI3.E3	TD.PD.VNDI3.E3 VDM Identity	FAIL
45	TD.PD.VNDI3.E6	TD.PD.VNDI3.E6 Unchunked Extended Messages Supported	FAIL
46	TD.PD.VNDI3.E7	TD.PD.VNDI3.E7 Security Msgs Supported	FAIL

PD2 Deterministic Tests- Result Summary

Sl No	Test ID	Test Name	Test Result
1	TD.PD.LL.E1	TD.PD.LL.E1 GoodCrc Timing	PASS
2	TD.PD.LL.E2	TD.PD.LL.E2 Retransmission	PASS
3	TD.PD.LL.E3	TD.PD.LL.E3 Soft Reset Usage	PASS
4	TD.PD.LL.E4	TD.PD.LL.E4 Hard Reset Usage	PASS
5	TD.PD.LL.E5	TD.PD.LL.E5 Soft Reset	PASS
6	TD.PD.SRC.E1	TD.PD.SRC.E1 Source Capabilities sent timely	PASS
7	TD.PD.SRC.E2	TD.PD.SRC.E2 Source Capabilities Fields Checks	PASS
8	TD.PD.SRC.E3	TD.PD.SRC.E3 SourceCapabilityTimer Timeout	PASS
9	TD.PD.SRC.E4	TD.PD.SRC.E4 SenderResponseTimer Deadline Request	PASS
10	TD.PD.SRC.E5	TD.PD.SRC.E5 SenderResponseTimer Timeout Request	PASS
11	TD.PD.SRC.E6	TD.PD.SRC.E6 PSHardResetTimer Timeout	PASS
12	TD.PD.SRC.E7	TD.PD.SRC.E7 Accept sent timely	PASS
13	TD.PD.SRC.E8	TD.PD.SRC.E8 Accept Fields Checks	PASS
14	TD.PD.SRC.E9	TD.PD.SRC.E9 PS RDY sent timely	PASS
15	TD.PD.SRC.E10	TD.PD.SRC.E10 PS RDY Fields Checks	PASS
16	TD.PD.SRC.E11	TD.PD.SRC.E11 Accept Requests can be met	PASS
17	TD.PD.SRC.E12	TD.PD.SRC.E12 Reject Requests cannot be met	PASS
18	TD.PD.SRC.E13	TD.PD.SRC.E13 Reject Request Invalid Object Position	PASS
19	TD.PD.SRC.E14	TD.PD.SRC.E14 Atomic Message Sequence	PASS
20	TD.PD.SRC.E15	TD.PD.SRC.E15 Give Source Cap	PASS
21	TD.PD.SRC.E16	TD.PD.SRC.E16 PDO Transition	PASS
22	TD.PD.VDMD.E1	TD.PD.VDMD.E1 tVDMSenderResponse Deadline Discover Identity	NA
23	TD.PD.VDMD.E2	TD.PD.VDMD.E2 tVDMSenderResponse Timeout Discover Identity	NA
24	TD.PD.VDMD.E3	TD.PD.VDMD.E3 Incorrect Fields Discover Identity	PASS
25	TD.PD.VDMD.E4	TD.PD.VDMD.E4 Applicability	PASS
26	TD.PD.VNDI.E4	TD.PD.VNDI.E4 SOP Handling	INCOMPLETE
27	TD.PD.VNDI.E5	TD.PD.VNDI.E5 Source Capabilities	INCOMPLETE
28	TD.PD.PHY.E1	TD.PD.PHY.E1 BIST Test Data	PASS
31	TD.PD.PHY.E4	TD.PD.PHY.E4 Transmitter Bit Rate and Bit Rate Drift	PASS
33	TD.PD.PHY.E6	TD.PD.PHY.E6 Receiver Swing Tolerance	PASS
34	TD.PD.PHY.E7	TD.PD.PHY.E7 Receiver Bit Rate Tolerance	PASS
35	TD.PD.PHY.E8	TD.PD.PHY.E8 Receiver Bit Rate Deviation Tolerance	PASS
36	TD.PD.PHY.E9	TD.PD.PHY.E9 Valid SOP Framing	PASS
37	TD.PD.PHY.E10	TD.PD.PHY.E10 Invalid SOP Framing	PASS
38	TD.PD.PHY.E11	TD.PD.PHY.E11 Valid SOP P Framing	PASS
39	TD.PD.PHY.E12	TD.PD.PHY.E12 Invalid SOP P Framing	PASS
40	TD.PD.PHY.E13	TD.PD.PHY.E13 Valid SOP PP Framing	PASS
41	TD.PD.PHY.E14	TD.PD.PHY.E14 Invalid SOP PP Framing	PASS
42	TD.PD.PHY.E15	TD.PD.PHY.E15 SOP P_Debug SOP PP Debug Framing	PASS
43	TD.PD.PHY.E16	TD.PD.PHY.E16 Valid Hard Reset Framing	PASS
44	TD.PD.PHY.E17	TD.PD.PHY.E17 Invalid Hard Reset Framing	PASS
45	TD.PD.PHY.E18	TD.PD.PHY.E18 Valid Cable Reset Framing	PASS
46	TD.PD.PHY.E19	TD.PD.PHY.E19 Invalid Cable Reset Framing	PASS
47	TD.PD.PHY.E20	TD.PD.PHY.E20 EOP Framing	PASS
48	TD.PD.PHY.E21	TD.PD.PHY.E21 Preamble	PASS

PD2 Communication Engine Tests- Result Summary

Sl No	Test ID	Test Name	Test Result
1	TDA.2.1.1.1	TDA.2.1.1.1 BMC PHY TX EYE	PASS
2	TDA.2.1.1.2	TDA.2.1.1.2 BMC PHY TX BIT	PASS
3	TDA.2.1.2.2	TDA.2.1.2.2 BMC PHY RX INT REJ	PASS
4	TDA.2.1.2.1	TDA.2.1.2.1 BMC PHY RX BUSIDL	PASS
5	TDA.2.1.3.1	TDA.2.1.3.1 BMC PHY TERM	PASS
6	TDA.2.1.3.2	TDA.2.1.3.2 BMC PHY MSG	PASS
7	TDA.2.2.1	TDA.2.2.1 BMC PROT SEQ GETCAPS	PASS
8	TDA.2.2.2.1	TDA.2.2.2.1 BMC PROT SEQ CHKCAB P PC	FAIL
9	TDA.2.2.2.2	TDA.2.2.2.2 BMC PROT SEQ CHKCAP NOMARK P PC	PASS
13	TDA.2.2.7	TDA.2.2.7 BMC PROT BIST NOT 5V SRC	PASS
15	TDA.2.2.9	TDA.2.2.9 BMC PROT GSC REC	PASS
16	TDA.2.3.1.1	TDA.2.3.1.1 POW SRC LOAD P PC	FAIL
17	TDA.2.3.2.1	TDA.2.3.2.1 POW SRC TRANS P PC	PASS